New Fourier transform infrared emission spectra of CaH and SrH: Combined isotopomer analyses with CaD and SrD

Article abstract of DOI:10.1016/j.molstruc.2003.11.001

In a search for the infrared spectra of gaseous CaH₂ and SrH₂, we obtained new Fourier transform infrared emission spectra of CaH and SrH, but no evidence of the metal dihydrides. The vibration-rotation bands from v=1→0 to v=4→3 of ⁴⁰CaH and ⁸⁸SrH, and the v=1→0 band of ⁸⁷SrH and ⁸⁶SrH were observed in the X²Σ⁺ ground electronic states. The new data were combined with the previous ground state data, obtained from diode laser infrared and pure rotational spectra, and the spectroscopic constants for v=0 to 4 of ⁴⁰CaH and ⁸⁸SrH were determined. In addition, the Dunham constants and the Born-Oppenheimer breakdown correction parameters were obtained using the previous ground state data for CaD and SrD in combined isotopomer fits. The equilibrium vibrational constants (ω_e) for CaH and SrH were found to be 1298.400(1) and 1207.035(1)cm^-1, respectively, while the equilibrium rotational constants (B_e) are 4.277043(4) and 3.673495(4)cm^-1. The equilibrium bond distances (r_e) were determined to be 2.0023603(9) A? for CaH and 2.1460574(10) A? for SrH.

Full text of DOI:10.1016/j.molstruc.2003.11.001

Journal of Molecular Structure 695–696 (2004) 23–37
www.elsevier.com/locate/molstruc
New Fourier transform infrared emission spectra of CaH and SrH:
combined isotopomer analyses with CaD and SrD
Alireza Shayesteha, Kaley A. Walkera, Iouli Gordonb, Dominique R.T. Appadooa,
Peter F. Bernatha,b,
*
aDepartment of Chemistry, University of Waterloo, Waterloo, Ont., N2L 3G1 Canada
bDepartment of Physics, University of Waterloo, Waterloo, Ont., N2L 3G1 Canada
Received 16 August 2003; revised 30 September 2003; accepted 3 November 2003
Abstract
In a search for the infrared spectra of gaseous CaH2 and SrH2, we obtained new Fourier transform infrared emission spectra of CaH and
SrH, but no evidence of the metal dihydrides. The vibration-rotation bands from v ¼ 1 ! 0 to v ¼ 4 ! 3 of 40CaH and 88SrH, and the
86
v ¼ 1 ! 0 band of 87SrH and SrH were observed in the X2Sþ ground electronic states. The new data were combined with the previous
ground state data, obtained from diode laser infrared and pure rotational spectra, and the spectroscopic constants for v ¼ 0 to 4 of 40CaH and
88SrH were determined. In addition, the Dunham constants and the Born–Oppenheimer breakdown correction parameters were obtained
using the previous ground state data for CaD and SrD in combined isotopomer fits. The equilibrium vibrational constants ðveÞ for CaH and
SrH were found to be 1298.400(1) and 1207.035(1) cm21, respectively, while the equilibrium rotational constants ðBeÞ are 4.277043(4) and
3.673495(4) cm21. The equilibrium bond distances ðreÞ were determined to be 2.0023603(9) A for CaH and 2.1460574(10) A for SrH.
q 2004 Elsevier B.V. All rights reserved.
˚
˚
Keywords: Vibration–rotation emission spectrum; CaH and SrH; Equilibrium molecular constants; Born–Oppenheimer breakdown constants
1. Introduction
for calcium monohydride and strontium monohydride,
which are described in this paper.
Most of the previous experimental work on the
spectroscopy of calcium monohydride has focused on its
electronic transitions. CaH was first observed in sunspot
spectra and was identified via its electronic spectrum [10,
11]. Early laboratory measurements, in the 1920s and 30s,
focused on emission spectroscopy from low-lying excited
electronic states [12–19]. During the 1960s and 70s, these
measurements were extended to include transitions in the
ultraviolet region, which led to the identification of several
Rydberg complexes [20–29]. Transitions involving the
low-lying excited states were reinvestigated in order to
examine perturbations which had been seen in earlier
spectra [30–39]. Most recently, CaH has been studied by
Zeeman [40,41] and REMPI [42] spectroscopy techniques.
The work on the electronic spectroscopy of strontium
monohydride parallels that of CaH, however, SrH has been
the subject of fewer studies. In the 1930s, the first band
systems of SrH to be studied were the electronic transitions
involving the low-lying excited electronic states [43–47].
Investigations involving higher energy excited electronic
We have recently undertaken a search for the infrared
spectra of gas phase alkaline earth dihydride molecules
using Fourier transform emission spectroscopy. Laboratory
measurements of these species are of interest because
theoretical calculations have predicted that the dihydrides of
the heavier alkaline earth atoms may have bent structures
whereas those for the lighter metal atoms are linear [1–5].
Our investigation started with the discovery of gaseous
BeH2 [6,7] while recording the infrared emission spectrum
of BeH [8]. Following this, a search was conducted for
MgH2 and its vibration–rotation spectrum was observed
[9]. In these studies, both BeH2 and MgH2 were found to
have linear geometries. Subsequent experiments were
carried out to search for the dihydrides of Ca, Sr and Ba,
but proved unsuccessful. However, in the course of these
measurements, new infrared emission spectra were obtained
*
Corresponding author.
E-mail address: bernath@uwaterloo.ca (P.F. Bernath).
0022-2860/$ - see front matter q 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.molstruc.2003.11.001

24
A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
states followed in the 1960s and 70s [48–57]. More
recently, there have been two studies which re-examined
transitions between low-lying electronic states and the
ground state using a Fourier transform spectrometer (FTS)
[58,59].
was heated to 780 8C in order to produce about 1 Torr vapor
pressure of calcium metal. About 1 Torr of hydrogen was
flowed through the cell, and a dc discharge (3 kV, 333 mA)
was struck between the electrodes. At intermediate
temperatures, from 650 to 750 8C, the hot metal absorbed
hydrogen and probably formed the solid metal dihydride
(CaH2). We had to keep the temperature at 780 8C to avoid
the hydrogen absorption process. The same experimental
setup was used for strontium, and a similar hydrogen
absorption reaction was observed, but the optimal tempera-
ture for strontium was 850 8C. A BaF2 lens was used to
focus the emission from CaH and SrH molecules onto the
entrance aperture of a Bruker IFS HR 120 FTS. The spectra
were recorded using a KBr beamsplitter and a liquid
nitrogen-cooled HgCdTe (MCT) detector at an instrumental
resolution of 0.01 cm21. The spectral region was limited to
800–1700 cm21 by the detector response, the BaF2 lens,
and a 1700 cm21 longwave pass filter. The spectra
contained CaH and SrH emission lines, as well as blackbody
emission from the hot tube and absorption lines from
atmospheric water vapor. Hundreds of scans were co-added
in order to improve the signal-to-noise ratios (600 scans for
CaH and 300 scans for SrH), and the achieved signal-to-
noise ratios for the strongest emission lines of CaH and SrH
were 50 and 25, respectively.
Ground state hyperfine interactions have been measured
for CaH and SrH trapped in an Ar matrix [60] and the
excited state hyperfine interactions, in the B2Sþ state of
CaH and the A2P1=2 state of SrH, have been investigated in
the gas phase [61]. Several calculations of potential energy
curves and molecular parameters have been made for CaH
[1,62–79] and SrH [1,69,76,80].
It is only in the last decade that the vibration–rotation
transitions in the X2Sþ ground electronic state of calcium
and strontium monohydride have been measured. The first
infrared study of CaH and CaD was done by Petitprez et al.
using a diode laser spectrometer [81]. They measured
transitions in four vibration–rotation bands, from v ¼
1 ˆ 0 to v ¼ 4 ˆ 3; however, the number of lines within
each band was limited by the spectral ranges of the diodes
available. Frum and Pickett [82] re-measured the funda-
mental and the first hot band of CaH in emission using a
FTS. In both cases, a furnace source with a dc discharge was
used to generate the molecules. The pure rotational spectra
of CaH and CaD were investigated by both Frum et al. [83]
and Barclay et al. [84].
Both diode laser and Fourier transform spectroscopy
have also been used to study the infrared spectra of SrH and
SrD. Three vibration–rotation bands (v ¼ 1 ˆ 0 to
v ¼ 3 ˆ 2) of SrH and SrD were recorded by Magg et al.
[85] and Birk et al. [86], respectively, using a diode laser
spectrometer. Frum et al. [87] recorded the v ¼ 1 ! 0 band
of SrH in emission using a FTS. As was done for CaH, the
gas phase molecules were produced in a furnace coupled
with a dc discharge. Frum et al. [87] also measured pure
rotational spectra of SrH and SrD using the same source and
a millimeter-wave spectrometer.
3. Results and analyses
The infrared emission spectrum of CaH contained
vibration–rotation bands in the ground electronic state of
the most abundant isotopomer (40CaH, 96.9%). The lines
from v ¼ 1 ! 0 to v ¼ 4 ! 3 transitions were found and
analyzed. The SrH spectrum contained vibration–rotation
bands of three isotopomers in the ground electronic state:
The v ¼ 1 ! 0 to v ¼ 4 ! 3 bands of 88SrH (82.6%), and
the v ¼ 1 ! 0 band of 87SrH (7.0%) and 86SrH (9.9%). The
blackbody emission from the hot tube was significant, and in
order to display the bands clearly, we corrected the baselines
of the spectra using the Bruker OPUS program. The
overviews of CaH and SrH spectra (after baseline correc-
tion) are shown in Figs. 1 and 2. The ground electronic
states of CaH and SrH are X2Sþ; and the spin-rotation
interaction splits the eðF1Þ and fðF2Þ parity levels. An
expanded view of the CaH spectrum in Fig. 3 shows the
splitting in all the bands. The lines from three isotopomers
of SrH were also resolved, and their intensity ratios are
consistent with their natural abundances, as shown in Fig. 4.
The program WSPECTRA [88] written by Carleer was used
to determine the line positions in the spectra. Both CaH and
SrH spectra were calibrated using the line lists of the
previous diode laser infrared measurements [81,85], and the
absolute accuracy of the calibrated lines is about
0.001 cm21. We assigned the experimental uncertainty of
0.001 cm21 to strong unblended lines. For very weak bands,
i.e. the v ¼ 4 ! 3 band of both molecules and the v ¼ 1 ! 0
We report here new Fourier transform infrared emission
spectra of CaH andþSrH containing four vibration–rotation
bands in their X2S ground electronic states. Analyses of
the new spectra have provided improved molecular
constants for these species. We also used the available
CaD and SrD data to study the Born–Oppenheimer
breakdown effects.
2. Experimental
An emission source that combines an electrical discharge
with a high temperature furnace was used to generate the
CaH and SrH molecules. About 50 g of calcium metal was
placed inside the central part of an alumina tube (120 cm
long and 5 cm diameter), and heated by a CM Rapid Temp
furnace. Two stainless steel tube electrodes were placed
inside the two ends of the tube, which were cooled by water
and sealed with BaF2 windows. The central part of the tube

A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
25
Fig. 1. An overview of the infrared emission spectrum of CaH after baseline
correction.
Fig. 3. An expanded view of the CaH spectrum showing the spin-splitting in
all the vibration–rotation bands.
band of 87SrH and 86SrH, the uncertainty of 0.002 cm21 was
used. The bands were found and assigned using a color
Loomis-Wood program.
constants to compute the hyperfine-free line positions. The
previous Fourier transform infrared spectra of Frum et al.
[82,87] contained two bands of 40CaH and one band of
88SrH, but we did not use their data because the signal-to-
noise ratios of our spectra are better. A complete list of the
line positions and assignments is in Table 1.
The available diode laser infrared spectra of CaH and
SrH contain four vibration–rotation bands of 40CaH/D [81]
and three bands of 88SrH/D [85,86], but there are only a few
lines in each band, and in some bands there are lines from
one branch (P or R) only. We found that for the R(9) and
R(10) rotational lines of the 40CaH v ¼ 4 ˆ 3 band reported
by Petitprez et al. [81], the e and f parity labels had to be
switched. This was also mentioned by Uehara [89]. We
included all the diode laser infrared lines in our data set, as
well as all the pure rotational data for 40CaH/D [83,84],
88SrH/D, and 86SrH/D [87]. For the pure rotational
transitions, we removed the hyperfine structure by
using the reported rotational and spin-rotation interaction
The Hamiltonian operator which includes the spin-
rotation interaction,
2
4
6
8
2
^
^
^
^
^
^
^
^
Hrfs ¼ BN 2 DN þ HN þ LN þ N·Sðg þ gDN Þ
ð1Þ
was used to obtain the rotational energy levels. The data for
v ¼ 0 to v ¼ 4 of 40CaH and 88SrH were fitted to the
analytical expression for the levels obtained from the above
Hamiltonian using the DPARFIT program [90] written by Le
Roy, and the band constants of Tables 2 and 3 were
Fig. 2. An overview of the infrared emission spectrum of SrH after baseline
correction.
Fig. 4. An expanded view of the SrH spectrum showing lines from three
isotopomers of strontium monohydride.

Table 1
Line positions of CaH and SrH (in cm1)
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
40CaH v ¼ 1 2 0
Rð32Þe
Rð31Þe
Rð30Þe
Rð29Þe
Rð18Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Rð10Þe
Rð9Þe
1405.4657(27)a
1405.5390(235)
1405.2964(236)
1404.7434(240)
1379.0237(213)
1374.9825(6)
1370.6750(1)
1366.1022(21)
1361.2676(3)
1356.1762(2)
1350.8310(2)
1345.2365(2)
1339.3961(3)
1333.3146(3)
1326.9955(4)
1320.4435(3)
1313.6624(5)
1306.6572(1)
1299.4313(1)
1291.9892(2)
1284.3356(3)
1276.4749(2)
1268.4113(2)
1405.4860(1)
1405.5503(39)
1405.3090(0)
1404.7533(1)
1379.0133(210)
1374.9716(26)
1370.6616(25)
Rð15Þf
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
Rð8Þf
Rð7Þf
Rð6Þf
Rð5Þf
Rð4Þf
Rð3Þf
Rð2Þf
Rð1Þf
Rð28Þ
Rð27Þ
Rð26Þ
Rð25Þ
Rð24)
Rð23Þ
Rð22Þ
Rð21Þ
Rð20Þ
Rð19Þ
Pð1Þe
Pð2Þe
Pð3Þe
Pð4Þe
Pð5Þe
1366.0865(23)
1361.2502(21)
1356.1567(0)
1350.8097(0)
1345.2131(1)
1339.3713(0)
1333.2879(1)
1326.9673(0)
1320.4134(1)
1313.6306(2)
1306.6235(1)
1299.3959(2)
1291.9524(2)
1284.2977(22)
1276.4347(4)
1403.8818(22)
1402.7157(17)
1401.2483(9)
1399.4823(21)
1397.4195(1)
1395.0647(0)
1392.4205(21)
1389.4903(21)
1386.2773(21)
1382.7844(6)
1251.6494(22)
1243.0022(2)
1234.1706(0)
1225.1580(1)
1215.9694(0)
Pð6Þe
1206.6091(0)
1197.0813(0)
1187.3906(0)
1177.5410(2)
1167.5373(1)
1157.3835(1)
1147.0837(1)
1136.6424(0)
1126.0635(0)
1115.3511(21)
1104.5091(0)
1093.5415(1)
1082.4525(1)
1071.2455(2)
1059.9247(2)
1048.4932(3)
1036.9555(21)
1025.3144(24)
1013.5729(21)
1001.7350(1)
989.8042(21)
977.7834(24)
965.6750(0)
Pð8Þe
1187.3911(25)b
1177.5413(21)b
1167.5371(3)b
1157.3844(28)b
1147.0832(6)b
1126.0638(23)b
1059.9250(22)b
1025.3145(25)b
1001.7354(23)b
989.8040(1)b
Pð20Þf
Pð21Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð25Þf
Pð26Þf
Pð27Þf
Pð28Þf
Pð29Þf
Pð30Þf
Pð31Þf
Pð5Þf
1059.9907(21)
1048.5600(0)
Pð7Þe
Pð9Þe
Pð8Þe
Pð10Þe
Pð11Þe
Pð12Þe
Pð14Þe
Pð20Þe
Pð23Þe
Pð25Þe
Pð26Þe
Pð28Þe
Pð30Þe
Pð2Þf
1037.0229(22)
1025.3812(10)
1013.6422(25)
1001.8045(2)
Pð9Þe
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
Pð21Þe
Pð22Þe
Pð23Þe
Pð24Þe
Pð25Þe
Pð26Þe
Pð27Þe
Pð28Þe
Pð29Þe
Pð30Þe
Pð31Þe
Pð32Þe
Pð5Þe
989.8742(2)
977.8547(28)
965.7478(214)
953.5564(215)
941.2826(25)
928.9289(20)
965.6750(0)b
941.2093(2)b
1243.0481(0)
1216.0194(22)b
1206.6600(1)b
1197.1344(28)b
1187.4451(211)b
1177.5950(8)b
1167.5943(211)b
1157.4413(28)b
1147.1412(6)b
1126.1232(4)b
1059.9902(3)b
1025.3810(11)b
1001.8048(22)b
989.8739(4)b
Pð3Þf
1234.2175(1)
Pð6Þf
Rð8Þe
Pð4Þf
1225.2065(0)
Pð7Þf
Rð7Þe
Pð5Þf
1216.0190(1)
Pð8Þf
Rð6Þe
Pð6Þf
1206.6600(0)
Pð9Þf
Rð5Þe
Pð7Þf
1197.1336(0)
Pð10Þf
Pð11Þf
Pð12Þf
Pð14Þf
Pð20Þf
Pð23Þf
Pð25Þf
Pð26Þf
Pð28Þf
Pð30Þf
Rð4Þe
Pð8Þf
1187.4441(21)
1177.5958(0)
Rð3Þe
Pð9Þf
Rð2Þe
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
Pð18Þf
Pð19Þf
1167.5934(22)
1157.4407(22)
1147.1419(21)
1136.7016(21)
1126.1236(21)
1115.4122(21)
1104.5713(21)
1093.6048(21)
1082.5167(21)
1071.3108(22)
Rð1Þe
Rð0Þe
Rð32Þf
Rð31Þf
Rð30Þf
Rð29Þf
Rð18Þf
Rð17Þf
Rð16Þf
953.4820(8)
941.2087(8)
928.8594(217)
916.4304(22)
1215.9698(23)b
1206.6085(6)b
1197.0826(213)b
965.7460(4)b
941.2804(17)b
Pð6Þe
Pð7Þe
40CaH v ¼ 2 2 1
Rð29Þe
Rð28Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Rð10Þe
Rð9Þe
1359.9770(9)
1359.3747(226)
1333.0401(220)
1328.9473(0)
1324.5897(22)
1319.9690(23)
1315.0890(0)
1309.9543(21)
1304.5683(0)
1298.9356(0)
1293.0600(1)
1286.9460(0)
Rð6Þe
Rð5Þe
Rð4Þe
Rð3Þe
Rð2Þe
Rð1Þe
Rð0Þe
Rð29Þf
Rð28Þf
Rð17Þf
Rð16Þf
Rð15Þf
1274.0187(3)
1267.2145(2)
1260.1886(4)
1252.9457(4)
1245.4905(2)
1237.8271(22)
1229.9583(10)
1359.9933(5)
1359.3883(226)
1333.0292(213)
1328.9351(0)
1324.5752(1)
Rð13Þf
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
Rð8Þf
Rð7Þf
Rð6Þf
Rð5Þf
Rð4Þf
Rð3Þf
Rð2Þf
1315.0713(23)
1309.9343(1)
1304.5465(2)
1298.9120(1)
1293.0346(2)
1286.9189(0)
1280.5686(2)
1273.9886(0)
1267.1823(3)
1260.1549(4)
1252.9106(3)
1245.4536(2)
Rð27Þ
Rð26Þ
Rð25Þ
Rð24Þ
Rð23Þ
Rð22Þ
Rð21Þ
Rð20Þ
Rð19Þ
Rð18Þ
Pð1Þe
Pð2Þe
1358.4630(29)
1357.2342(56)
1355.7135(14)
1353.8907(21)
1351.7709(26)
1349.3578(0)
1346.6563(0)
1343.6693(0)
1340.4011(24)
1336.8536(2)
1213.5878(23)
1205.1336(0)
Pð4Þe
1187.6720(22)
1178.6730(21)
1169.5011(1)
Pð5Þe
Pð6Þe
Pð7Þe
1160.1608(1)
Pð8Þe
1150.6566(21)
1140.9924(22)
1131.1725(22)
1121.2010(0)
Pð9Þe
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
1111.0827(21)
1100.8210(0)
1090.4205(22)
1079.8849(24)
Rð8Þe

Rð7Þe
1280.5972(3)
1058.4238(23)
1047.5061(23)
1036.4684(0)
1014.0486(22)
1002.6731(23)
991.1912(2)
Rð14Þf
Pð3Þe
1319.9531(24)
1196.4933(2)b
1187.6717(2)b
1169.5016(24)b
1131.1729(26)b
1047.5055(3)b
1036.4682(2)b
1002.6730(22)b
991.1915(22)b
979.6064(8)b
Rð1Þf
1237.7887(22)
1187.7188(0)
Pð3Þe
1196.4933(2)
1069.2787(21)
1058.4853(2)
1047.5688(21)
1036.5322(21)
1014.1139(21)
1002.7388(3)
991.2585(21)
979.6749(2)
Pð16Þe
Pð3Þf
1069.2178(22)
1196.5394(22)b
1187.7193(25)b
1169.5510(22)b
1131.2271(23)b
1036.5318(3)b
1002.7380(11)b
991.2582(2)b
Pð17Þe
Pð18Þe
Pð19Þe
Pð21Þe
Pð22Þe
Pð23Þe
Pð24Þe
Pð25Þe
Pð26Þe
Pð27Þe
Pð28Þe
Pð1Þe
Pð4Þf
Pð16Þf
Pð17Þf
Pð18Þf
Pð19Þf
Pð21Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð25Þf
Pð26Þf
Pð27Þf
Pð28Þf
Pð4Þe
Pð5Þf
1178.7213(0)
Pð4Þf
Pð6Þe
Pð6Þf
1169.5508(0)
Pð6Þf
Pð10Þe
Pð18Þe
Pð19Þe
Pð22Þe
Pð23Þe
Pð24Þe
Pð25Þe
Pð2Þf
Pð7Þf
1160.2118(0)
Pð10Þf
Pð19Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð8Þf
1150.7088(22)
1141.0455(0)
Pð9Þf
979.6070(2)
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
1131.2270(22)
1121.2571(24)
1111.1396(23)
1100.8791(23)
1090.4795(23)
1079.9447(22)
967.9244(28)
956.1445(29)
944.2694(6)
979.6730(21)b
967.9924(22)
956.2125(3)
967.9237(21)b
1205.1768(10)
1196.5393(21)
932.3056(0)
1213.5877(22)b
944.3416(217)
932.3756(6)
Pð3Þf
40CaH v ¼ 3 2 2
Rð25Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Rð10Þe
Rð9Þe
1311.3740(6)
1286.8741(2)
1282.7493(27)
1278.3562(7)
1273.7031(3)
1268.7921(21)
1263.6270(0)
1258.2128(22)
1252.5530(2)
1246.6530(21)
1240.5161(0)
1234.1471(2)
1227.5504(2)
1220.7303(3)
1213.6924(28)
1206.4390(27)
1198.9726(22)
1213.6926(29)b
1198.9756(29)b
1191.3046(10)b
1311.3844(211)
1286.8640(22)
1282.7353(9)
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
Rð8Þf
Rð7Þf
Rð6Þf
Rð5Þf
Rð4Þf
Rð3Þf
Rð2Þf
Rð3Þf
Rð1Þf
Rð24Þ
Rð23Þ
Rð22Þ
Rð21Þ
Rð20Þ
Rð19Þ
Rð18Þ
Rð17Þ
1278.3421(4)
1273.6863(7)
1268.7736(2)
1263.6061(8)
1258.1909(21)
1252.5291(4)
1246.6271(4)
1240.4893(22)
1234.1185(0)
1227.5198(3)
1220.6984(1)
1213.6559(20)
1206.4031(22)
1213.6584(25)b
1198.9389(211)b
1309.8264(216)
1307.9702(25)
1305.8162(8)
1303.3685(21)
1300.6336(7)
1297.6113(7)
1294.3086(210)
1290.7253(21)
Pð1Þe
1175.3310(241)
1167.0656(6)
1158.6182(26)
1149.9858(22)
1141.1745(0)
1132.1890(22)
1123.0332(24)
1113.7107(21)
1104.2264(2)
1094.5850(0)
1084.7896(2)
1074.8456(23)
1064.7548(6)
1054.5241(22)
1044.1541(7)
1033.6519(1)
1023.0186(4)
1012.2595(2)
1001.3777(24)
990.3755(0)
Pð24Þe
Pð25Þe
Pð1Þe
Pð2Þe
Pð4Þe
Pð6Þe
Pð13Þe
Pð15Þe
Pð18Þe
Pð20Þe
Pð23Þe
Pð2Þf
945.2408(227)
933.6918(252)
1175.3271(22)b
1167.0667(26)b
1149.9850(6)b
1132.1888(1)b
1064.7557(24)b
1044.1546(2)b
1012.2592(4)b
990.3744(11)b
956.6852(6)b
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
Pð18Þf
Pð19Þf
Pð20Þf
Pð21Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð25Þf
Pð2Þf
1054.5812(4)
1044.2133(3)
1033.7121(24)
1023.0795(3)
1012.3203(10)
1001.4404(24)
990.4375(15)
979.3237(219)
968.0962(244)
956.7519(22)
945.3041(9)
Pð2Þe
Pð3Þe
Pð4Þe
Pð5Þe
Pð6Þe
Pð7Þe
Pð8Þe
Pð9Þe
Rð8Þe
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
Pð21Þe
Pð22Þe
Pð23Þe
Rð7Þe
Rð6Þe
1167.1097(27)
1158.6623(25)
1150.0308(4)
1141.2211(4)
1132.2370(1)
1123.0825(22)
1113.7617(23)
1104.2784(3)
1094.6381(1)
1084.8440(3)
1074.9006(2)
1064.8118(1)
933.7569(227)
1167.1093(23)b
1150.0307(5)b
1132.2368(3)b
1064.8115(4)b
1044.2128(7)b
1012.3210(3)b
990.4395(25)b
956.7527(29)b
Rð5Þe
Pð3Þf
Rð4Þe
Pð4Þf
Pð4Þf
Rð3Þe
Pð5Þf
Pð6Þf
Rð2Þe
Pð6Þf
Pð13Þf
Pð15Þf
Pð18Þf
Pð20Þf
Pð23Þf
Rð1Þe
Pð7Þf
Rð3Þe
Pð8Þf
Rð1Þe
Pð9Þf
Rð0Þe
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Rð25Þf
Rð16Þf
Rð15Þf
979.2582(27)
968.0273(28)
956.6885(227)
40CaH v ¼ 4 2 3
Rð15Þe
1240.2913(27)
1236.1490(14)
1231.7456(219)
1227.0723(27)
1222.1476(10)
1216.9703(214)
1211.5420(216)
1256.8427(22)
1254.0993(29)
Rð8Þe
Rð7Þe
Rð6Þe
Rð4Þe
Rð3Þe
Rð10Þe
Rð9Þe
Pð9Þe
Pð10Þe
1205.8689(215)
1199.9549(24)
1193.8051(10)
1180.8205(5)
Rð5Þe
Rð3Þe
Rð1Þe
Rð0Þe
Rð15Þf
Rð14Þf
Rð13Þf
Pð20Þe
Pð21Þe
1187.4255(13)b
1173.9933(21)b
1159.6893(4)b
1152.2230(0)b
1240.2790(10)
1236.1370(8)
1231.7289(3)
954.8304(14)
943.8374(24)
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
Rð8Þf
Rð7Þf
Rð6Þf
Pð8Þf
Pð9Þf
1227.0597(211)
1222.1295(8)
Rð4Þf
Rð3Þf
Rð10Þf
Rð9Þf
Rð3Þf
Rð1Þf
Rð21Þ
Pð18Þf
Pð19Þf
1180.7897(7)
1173.9604(6)
Rð14Þe
Rð13Þe
1216.9489(22)
1211.5173(11)
1205.8425(11)
1199.9303(212)
1193.7787(3)
1216.9498(211)b
1211.5187(23)b
1173.9609(1)b
Rð12Þe
Rð11Þe
1173.9909(24)
1216.9702(213)b
1211.5408(25)b
1067.0129(26)
1057.5419(210)
Rð10Þe
1159.6539(4)b
Rð9Þe
1259.2923(20)
Rð20Þ
1076.3726(23)
1067.0628(2)
976.5125(228)
965.7643(22)
(continued on next page)
Rð19Þ

Table 1 (continued)
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Rð18Þ
Rð17Þ
Rð16Þ
Pð3Þe
Pð4Þe
Pð6Þe
Pð7Þe
Pð8Þe
1251.0679(215)
1247.7517(211)
1244.1566(214)
1120.3195(219)
1111.8736(3)
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
1047.9133(26)
1038.1329(211)
1028.2019(0)
Pð22Þe
Pð10Þe
Pð15Þe
Pð19Þe
Pð3Þf
932.7271(25)
1057.5412(23)b
1007.9109(22)b
965.7020(6)b
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
1057.5935(27)
1047.9657(1)
1038.1856(5)
1028.2551(22)
1018.1841(27)
1007.9674(8)
997.6165(213)
987.1291(212)
Pð20Þf
Pð21Þf
Pð22Þf
Pð10Þf
Pð15Þf
Pð19Þf
954.8942(0)
943.8988(42)
932.7951(214)
1057.5937(29)b
1007.9689(27)b
965.7639(2)b
1018.1285(215)
1007.9123(216)
997.5575(29)
987.0671(12)
1120.3573(32)
1111.9175(5)
1094.4911(7)
1085.5165(1)
1094.4442(8)
Pð4Þf
1085.4669(15)
1076.3223(5)
Pð6Þf
976.4490(3)
Pð7Þf
40CaH
v0
0
0
0
0
0
0
N0
1
p0
e
f
v00
0
0
0
0
0
0
N00
0
p00
e
e
e
e
e
f
v0
1
1
2
2
3
3
4
N0
1
0
1
0
1
0
1
p0
f
v00
0
0
1
1
2
2
3
N00
0
p00
e
f
8.4784175(23)c
8.4130846(22)c
8.478417(0)d
16.930598(23)d
8.413082(3)d
16.887089(0)d
1268.3474(9)
1
0
e
f
1
1251.7135(11)
1229.8984(21)
1213.6559(252)
1191.2469(21)b
1175.3907(228)b
1152.1658(6)b
1
e
e
f
0
0
e
f
2
1
e
f
1
1
0
0
e
f
2
f
1
e
f
1
0
e
40CaD
v0
0
0
0
0
0
0
N0
1
p0
e
e
f
v00
0
0
0
0
0
0
N00
0
p00
e
e
f
v0
0
0
0
0
2
N0
5
p0
e
f
v00
0
0
0
0
1
N00
4
p00
e
f
4.3649077(65)c
8.7174326(13)c
8.6950164(259)c
13.0676078(21)c
13.067636(228)d
17.414282(216)d
21.756254(211)d
13.045170(34)d
17.391882(9)d
21.733903(0)d
894.8975(0)b
2
1
3
2
2
1
4
f
3
f
3
e
e
e
2
e
e
e
5
f
4
f
3
2
1
f
0
e
4
3
40CaD v ¼ 1 2 0
Rð26Þe
Rð25Þe
Rð24Þe
Rð22Þe
Rð20Þe
Rð13Þe
Rð9Þe
997.2249(1)b
995.1867(5)b
993.0504(24)b
988.4799(12)b
983.5253(9)b
963.2602(7)b
949.7417(213)b
946.1496(11)b
942.4795(0)b
934.8964(5)b
930.9868(10)b
Rð3Þe
Rð1Þe
Rð26Þf
Rð25Þf
Rð24Þf
Rð22Þf
Rð20Þf
Rð13Þf
Rð9Þf
927.0018(0)b
Rð5Þf
Rð4Þf
Rð3Þf
Rð1Þf
Rð36Þ
Rð32Þ
Rð30Þ
Rð27Þ
Pð1Þe
Pð2Þe
Pð4Þe
934.8770(10)b
930.9677(7)b
Pð5Þe
887.8300(13)b
878.3832(22)b
873.5634(5)b
863.7413(0)b
858.7403(0)b
853.6813(24)b
848.5642(0)b
832.8828(23)b
827.5482(1)b
901.5348(25)b
892.4812(11)b
Pð5Þf
887.8560(0)b
918.8041(27)b
997.2208(28)b
995.1818(24)b
993.0440(25)b
988.4718(14)b
983.5162(6)b
Pð7Þe
Pð7Þf
878.4084(3)b
926.9829(211)b
918.7831(28)b
1011.9381(23)b
1007.3130(26)b
1004.3619(6)b
999.1603(21)b
905.9359(29)b
901.5119(28)b
892.4578(3)b
Pð8Þe
Pð8Þf
873.5903(23)b
863.7687(23)b
858.7675(3)b
853.7100(212)b
848.5928(22)b
832.9127(26)b
827.5788(25)b
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð16Þe
Pð17Þe
Pð2Þf
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð16Þf
Pð17Þf
Rð8Þe
963.2462(7)b
Rð7Þe
949.7249(210)b
946.1334(2)b
Rð5Þe
Rð8Þf
Rð4Þe
Rð7Þf
942.4620(22)b
Pð4Þf
40CaD v ¼ 2 2 1
Rð16Þe
951.6542(3)b
945.7399(1)b
942.6510(216)b
939.4711(4)b
911.0172(2)b
907.1028(2)b
Rð10Þe
Rð8Þe
Rð6Þe
Rð5Þe
Pð4Þe
Pð6Þe
932.8581(22)b
925.9082(21)b
918.6311(1)b
914.8734(25)b
873.1489(4)b
863.9712(25)b
Rð4Þe
Rð3Þe
Rð2Þe
Rð0Þe
Pð11Þe
Pð4Þf
911.0355(8)b
907.1191(34)b
903.1315(11)b
894.9295(0)b
839.9187(22)b
873.1726(4)b
Rð16Þf
Rð14Þf
Rð13Þf
Rð12Þf
Pð8Þf
951.6429(1)b
Rð10Þf
Rð8Þf
Rð6Þf
Rð5Þf
932.8428(22)b
925.8916(0)b
918.6131(4)b
914.8549(23)b
Rð14Þe
945.7274(22)b
942.6376(216)b
939.4577(23)b
854.5621(217)b
839.9450(5)b
Rð13Þe
Rð12Þe
Rð4Þf
Rð3Þf
Pð11Þf

Rð2Þf
903.1080(46)b
Pð8Þe
854.5362(214)b
Pð6Þf
863.9953(1)b
40CaD v ¼ 3 2 2
Rð17Þe
933.5079(2)b
Rð10Þe
Rð7Þe
Rð6Þe
Rð5Þe
Rð17Þf
912.4248(1)b
902.1007(0)b
898.4956(2)b
894.8111(0)b
933.4979(1)b
Rð16Þf
Rð15Þf
Rð13Þf
Rð12Þf
Rð10Þf
930.7533(22)b
927.9166(6)b
Rð7Þf
Rð6Þf
Rð5Þf
Pð4Þe
Pð5Þe
902.0846(25)b
898.4787(21)b
894.7923(10)b
853.8065(23)b
849.3189(9)b
Pð7Þe
Pð4Þf
Pð5Þf
840.1543(237)b
853.8293(1)b
849.3431(4)b
Rð16Þe
930.7643(23)b
927.9269(18)b
921.9901(27)b
918.8876(21)b
Rð15Þe
921.9767(21)b
918.8741(0)b
Rð13Þe
Rð12Þe
912.4119(218)b
40CaD v ¼ 4 2 3
Rð15Þe
907.0060(2)b
904.1610(22)b
898.2017(8)b
895.0918(2)b
Rð10Þe
Rð8Þe
Rð6Þe
Rð5Þe
891.8955(21)b
885.2468(17)b
878.2718(28)b
874.6611(2)b
Rð15Þf
Rð14Þf
Rð12Þf
Rð11Þf
906.9957(24)b
904.1493(21)b
898.1886(11)b
895.0786(21)b
Rð10Þf
Rð8Þf
Rð6Þf
Rð5Þf
891.8834(221)b
885.2333(22)b
878.2561(216)b
874.6444(23)b
Rð14Þe
Rð12Þe
Rð11Þe
88SrH v ¼ 1 2 0
Rð35Þe
Rð34Þe
Rð33Þe
Rð32Þe
Rð31Þe
Rð30Þe
Rð29Þe
Rð28Þe
Rð27Þe
Rð26Þe
Rð25Þe
Rð24Þe
Rð23Þe
Rð22Þe
Rð21Þe
Rð20Þe
Rð19Þe
Rð18Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Rð10Þe
Rð9Þe
1303.8152(22)
1304.1852(218)
1304.2958(21)
1304.1538(4)
1303.7593(16)
1303.1187(27)
1302.2274(3)
1301.0921(1)
1299.7137(0)
1298.0953(210)
1296.2385(218)
1294.1428(1)
1291.8127(29)
1289.2553(15)
1286.4692(2)
1283.4558(1)
1280.2184(2)
1276.7601(2)
1273.0835(2)
1269.1913(1)
1265.0858(5)
1260.7709(2)
1256.2486(2)
1251.5220(1)
1246.5940(0)
1241.4676(0)
1236.1457(1)
1230.6315(1)
930.8169(217)
920.3980(23)
Rð7Þe
Rð6Þe
Rð5Þe
Rð4Þe
Rð3Þe
Rð2Þe
Rð1Þe
Rð0Þe
Rð13Þe
Rð8Þe
Rð6Þe
Rð5Þe
Rð2Þe
Rð35Þf
Rð34Þf
Rð33Þf
Rð32Þf
Rð31Þf
Rð30Þf
Rð29Þf
Rð28Þf
Rð27Þf
Rð26Þf
Rð25Þf
Rð24Þf
Rð23Þf
Rð22Þf
Rð21Þf
Pð30Þf
Pð3Þf
1224.9277(5)
1219.0387(0)
1212.9657(3)
1206.7134(2)
1200.2831(14)
1193.6814(3)
1186.9088(1)
1179.9687(2)
1256.2493(25)e
1230.6317(0)e
1219.0384(3)e
1212.9656(5)e
1193.6814(4)e
1303.8753(36)
1304.2403(9)
1304.3487(211)
1304.2003(21)
1303.7998(12)
1303.1528(26)
1302.2558(3)
1301.1148(0)
1299.7294(11)
1298.1050(5)
1296.2385(38)
1294.1428(1)
1291.8127(227)
1289.2470(211)
1286.4530(0)
899.3316(10)
1150.6037(21)e
Rð20Þf
Rð19Þf
Rð18Þf
Rð17Þf
Rð16Þf
Rð15Þf
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
1283.4341(22)
1280.1917(23)
1276.7279(21)
1273.0461(22)
1269.1486(21)
1265.0383(0)
Pð4Þe
1142.7394(21)
1134.8616(0)
1126.8398(22)
1118.6767(0)
1110.3762(21)
1101.9409(21)
1093.3744(21)
1084.6798(22)
1075.8598(1)
1066.9186(22)
1057.8581(21)
1048.6821(0)
1039.3934(0)
1029.9951(21)
1020.4900(21)
1010.8810(2)
1001.1714(1)
991.3636(0)
Pð8Þe
Pð9Þe
Pð11Þe
Pð2Þf
1110.3763(23)e
1101.9400(8)e
1084.6805(29)e
1158.1783(10)
1150.6041(25)
1142.8775(24)
1135.0028(4)
1126.9847(2)
1118.8259(22)
1110.5283(3)
1102.0970(21)
1093.5339(0)
1084.8425(0)
1076.0260(2)
1067.0877(1)
1058.0305(1)
1048.8576(0)
1039.5720(21)
1030.1763(2)
1020.6740(2)
1011.0677(4)
1001.3608(2)
991.5557(1)
Pð5Þe
Pð6Þe
Pð7Þe
Pð8Þe
Pð3Þf
Pð9Þe
Pð4Þf
1260.7179(1)
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
Pð21Þe
Pð22Þe
Pð23Þe
Pð24Þe
Pð25Þe
Pð26Þe
Pð27Þe
Pð28Þe
Pð3Þe
Pð5Þf
1256.1907(0)
Pð6Þf
1251.4591(21)
1246.5261(0)
Pð7Þf
Pð8Þf
1241.3947(2)
Pð9Þf
1236.0679(4)
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
Pð18Þf
Pð19Þf
Pð20Þf
Pð21Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð25Þf
Pð26Þf
Pð11Þf
Rð8Þf
1230.5494(0)
Rð7Þf
1224.8414(21)
1218.9470(1)
Rð6Þf
Rð5Þf
1212.8701(21)
1206.6130(0)
Rð4Þf
Rð3Þf
1200.1796(22)
1193.5726(22)
1186.7950(3)
Rð2Þf
981.4605(1)
Rð1Þf
971.4647(2)
Rð13Þf
Rð8Þf
1256.1906(1)e
1230.5500(26)e
1218.9469(2)e
1212.8698(2)e
1193.5715(10)e
1165.4772(224)
1158.0489(3)
961.3789(5)
951.2055(11)
940.9488(3)
Rð6Þf
Rð5Þf
930.6094(1)
981.6553(21)
971.6621(21)
961.5796(28)
951.4086(24)
941.1541(213)
1084.8427(22)e
Rð2Þf
920.1938(238)
1150.4691(5)e
1142.7403(210)e
1118.6767(0)e
1110.5286(0)e
1102.0962(7)e
Pð1Þe
Pð2Þe
Pð3Þe
Pð4Þf
Pð4Þe
Rð8Þe
1150.4698(21)
1142.8788(216)e
1118.8257(0)e
Pð7Þe
Pð27Þf
Pð28Þf
Pð8Þf
Pð7Þf
Pð9Þf
88SrH v ¼ 2 2 1
Rð29Þe
1262.8801(4)
1261.9373(5)
Rð3Þe
Rð2Þe
1165.4772(12)
Rð13Þf
Rð12Þf
1219.7236(22)
1215.1616(0)
Pð8Þe
Pð9Þe
1077.4889(23)
1069.2092(25)
Pð6Þf
Pð7Þf
1093.7806(2)
1085.7786(25)
(continued on next page)
Rð28Þe
1159.0389(22)

Table 1 (continued)
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Line
Wavenumber
Rð27Þe
Rð26Þe
Rð25Þe
Rð24Þe
Rð23Þe
Rð22Þe
Rð21Þe
Rð20Þe
Rð19Þe
Rð18Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Rð10Þe
Rð9Þe
1260.7474(23)
1259.3197(210)
1257.6501(230)
1255.7388(212)
1253.5912(14)
1251.2100(48)
1248.6066(1)
Rð1Þe
1152.4284(23)
1145.6492(8)
Rð11Þf
Rð10Þf
Rð9Þf
Rð8Þf
Rð7Þf
Rð6Þf
Rð5Þf
Rð4Þf
Rð3Þf
Rð2Þf
Rð1Þf
Rð13Þf
Rð11Þf
Rð10Þf
Rð6Þf
Rð4Þf
Rð3Þf
Pð1Þe
Pð2Þe
Pð3Þe
Pð4Þe
Pð5Þe
Pð6Þe
Pð7Þe
1210.3976(0)
1205.4341(4)
1200.2746(8)
1194.9229(4)
1189.3808(5)
1183.6522(4)
1177.7404(22)
1171.6472(3)
1165.3776(21)
1158.9344(29)
1152.3193(27)
1219.7244(210)e
1210.3980(24)e
1205.4341(4)e
1183.6528(22)e
1171.6477(22)e
1165.3764(11)e
1131.4824(28)
1124.2169(210)
1116.7954(2)
1109.2236(4)
1101.5041(1)
1093.6393(2)
1085.6333(0)
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
Pð21Þe
Pð22Þe
Pð23Þe
Pð24Þe
Pð25Þe
Pð26Þe
Pð27Þe
Pð5Þe
1060.7973(27)
1052.2556(1)
1043.5891(22)
1034.8001(26)
1025.8907(23)
1016.8650(23)
1007.7257(24)
998.4754(0)
Pð8Þf
1077.6368(2)
1069.3606(0)
1060.9519(1)
1052.4143(1)
1043.7512(23)
1034.9647(21)
1026.0586(0)
1017.0361(22)
1007.8994(2)
998.6520(5)
Rð0Þe
Pð9Þf
Rð13Þe
Rð11Þe
Rð10Þe
Rð6Þe
1219.7788(211)e
1210.4621(24)e
1205.5037(23)e
1183.7407(25)e
1171.7443(22)e
1165.4776(9)e
1263.6122(4)
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
Pð18Þf
Pð19Þf
Pð20Þf
Pð21Þf
Pð22Þf
Pð23Þf
Pð24Þf
Pð25Þf
Pð26Þf
Pð27Þf
Pð5Þf
Rð4Þe
1245.7703(6)
Rð3Þe
1242.7099(4)
Rð30Þf
Rð29Þf
Rð28Þf
Rð27Þf
Rð26Þf
Rð24Þf
Rð23Þf
Rð22Þf
Rð21Þf
Rð20Þf
Rð19Þf
Rð18Þf
Rð17Þf
Rð16Þf
Rð15Þf
Rð14Þf
989.1179(23)
979.6546(3)
1239.4276(21)
1235.9248(4)
1262.9115(5)
1261.9639(21)
1260.7709(29)
1259.3341(29)
1255.7388(22)
1253.5912(27)
1251.2100(228)
1248.5938(21)
1245.7532(26)
1242.6862(5)
970.0903(23)
960.4261(22)
950.6656(25)
940.8100(3)
989.2975(0)
1232.2061(1)
979.8375(1)
1228.2734(0)
970.2749(5)
1224.1297(21)
1219.7775(2)
960.6134(4)
930.8638(4)
950.8546(9)
1215.2208(21)
1210.4621(25)
1205.5034(0)
920.8328(238)
910.7072(3)
941.0026(5)
931.0589(3)
900.5023(24)
1101.5038(4)e
1069.2085(2)e
1124.3420(22)
1116.9254(0)
1109.3577(21)
1101.6412(5)
921.0253(11)
910.9089(220)
900.7029(5)
1101.6411(6)e
1069.3603(2)e
1200.3492(22)
1195.0016(0)
Rð8Þe
1239.3989(23)
1235.8908(3)
Pð9Þe
Rð7Þe
1189.4644(21)
1183.7406(24)
1177.8322(1)
Pð2Þf
Rð6Þe
1232.1670(0)
Pð3Þf
Pð9Þf
Rð5Þe
1228.2289(2)
Pð4Þf
Rð4Þe
1171.7442(22)
1224.0803(0)
Pð5Þf
88SrH v ¼ 3 2 2
Rð24Þe
Rð23Þe
Rð22Þe
Rð21Þe
Rð20Þe
Rð19Þe
Rð18Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Rð11Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
1217.0663(210)
1215.1206(24)
1212.9382(13)
1210.5245(15)
1207.8814(10)
1205.0114(3)
1201.9168(22)
1198.6000(1)
1195.0646(5)
1191.3143(1)
1187.3512(21)
1183.1778(4)
1178.7987(0)
1174.2157(23)
993.8210(26)
984.9393(23)
975.9429(25)
966.8333(3)
Rð10Þe
Rð9Þe
Rð8Þe
Rð7Þe
Rð6Þe
Rð5Þe
Rð4Þe
Rð3Þe
Rð2Þe
Rð1Þe
Rð0Þe
Rð15Þe
Rð13Þe
Rð11Þe
Pð21Þe
Pð22Þe
Pð5Þe
Pð6Þe
Pð2Þf
1169.4315(4)
1164.4508(1)
1159.2760(25)
1153.9090(1)
1148.3547(21)
1142.6151(3)
1136.6946(21)
1130.5954(21)
1124.3202(7)
1117.8743(2)
1111.2611(216)
1191.3140(4)e
1183.1778(4)e
1174.2153(2)e
929.3364(256)
919.7014(2)
Rð10Þe
Rð6Þe
Rð5Þe
Rð22Þf
Rð20Þf
Rð19Þf
Rð18Þf
Rð17Þf
Rð16Þf
Rð15Þf
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Pð5Þf
1169.4316(3)e
1148.3535(11)e
1142.6168(214)e
1212.9382(228)
1207.8686(29)
1204.9920(23)
1201.8915(22)
1198.5704(28)
1195.0292(3)
Rð10Þf
Rð9Þf
1169.3667(1)
1164.3811(21)
1159.2016(25)
1153.8298(2)
1148.2703(7)
1142.5267(5)
1136.6018(2)
1130.4980(3)
1124.2169(28)
1117.7653(38)
1191.2736(2)e
1183.1274(2)e
1174.1552(0)e
1169.3673(25)e
1011.3835(1)
1002.7444(2)
993.9841(2)
Rð6Þf
1148.2676(34)e
1142.5285(213)e
1090.3144(215)
1083.0517(0)
Rð5Þf
Rð8Þf
Pð2Þe
Pð3Þe
Pð4Þe
Pð5Þe
Pð6Þe
Pð7Þe
Pð8Þe
Pð9Þe
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð19Þf
Pð21Þf
Pð22Þf
Pð5Þf
Rð7Þf
Rð6Þf
1075.6371(9)
Rð5Þf
1068.0764(212)
1060.3661(3)
Rð4Þf
Rð3Þf
1052.5149(21)
1044.5233(3)
Rð2Þf
1191.2731(7)
Rð1Þf
1036.3963(23)
1028.1359(28)
1019.7448(28)
1011.2261(22)
1002.5837(0)
1187.3056(21)
1183.1281(25)
1178.7423(9)
Rð15Þf
Rð13Þf
Rð11Þf
Rð10Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
Pð18Þf
1174.1550(2)
1068.2084(0)
948.4693(28)
929.5145(22)
919.8887(210)
1068.2080(5)e
1060.5004(29)e
Pð6Þf
1060.5035(22)
1052.6551(3)
1068.0748(4)e
1060.3634(30)e
1090.4373(226)
1083.1780(26)
1075.7676(21)
Pð7Þf
Pð8Þf
1044.6669(9)
985.1060(0)
957.6155(23)
948.2890(12)
938.8612(0)
Pð9Þf
1036.5439(22)
1028.2867(25)
1019.8986(21)
976.1119(5)
Pð6Þf
Pð3Þf
Pð10Þf
Pð11Þf
967.0058(6)
Pð4Þf
957.7911(22)

88SrH v ¼ 4 2 3
Rð24Þe
1177.8902(255)
1172.0059(216)
1166.9112(28)
1164.0180(25)
1160.9063(22)
1157.5700(2)
Rð9Þe
Rð8Þe
Rð7Þe
Rð6Þe
Rð5Þe
Rð4Þe
Rð24Þf
Rð22Þf
Rð21Þf
Rð19Þf
Rð18Þf
Rð17Þf
1128.2788(21)
1123.2831(4)
Rð16Þf
Rð15Þf
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Rð10Þf
Rð9Þf
1157.5371(12)
1153.9778(12)
1150.2067(223)
1146.2172(5)
Pð4Þe
1041.8301(243)
1034.4175(9)
1026.8626(6)
1019.1634(2)
1011.3219(6)
1003.3405(26)
995.2297(211)
986.9819(1)
Pð16Þe
Pð5Þf
943.8728(219)
1034.5464(12)
1019.2977(24)
1011.4612(13)
1003.4871(25)
995.3764(29)
987.1326(24)
978.7597(21)
970.2620(210)
961.6404(214)
952.8963(3)
Rð21Þe
Pð5Þe
Rð19Þe
1118.0963(212)
1112.7162(5)
Pð6Þe
Pð7Þf
Rð18Þe
Pð7Þe
Pð8Þf
Rð17Þe
1107.1519(21)
1101.4051(216)
1177.8902(47)
1174.1989(26)
1171.9956(27)
1166.8947(28)
1163.9992(23)
1160.8823(230)
1142.0232(211)
1137.6222(216)
1133.0159(5)
Pð8Þe
Pð9Þf
Rð16Þe
Pð9Þe
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Rð15Þe
1154.0154(5)
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Rð14Þe
1150.2468(25)
1146.2652(27)
1142.0733(4)
1128.2128(21)
1123.2141(213)
1118.0204(25)
1112.6384(213)
1101.3140(9)
Rð13Þe
Rð8Þf
978.6061(2)
Rð12Þe
Rð7Þf
970.1061(217)
961.4837(245)
952.7341(23)
Rð11Þe
1137.6753(17)
1133.0775(2)
Rð6Þf
Rð10Þe
Rð4Þf
944.0355(12)
87SrH v ¼ 1 2 0
Rð25Þe
1296.3254(236)
1294.2283(22)
1283.5401(9)
Rð11Þe
Rð10Þe
Rð8Þe
1246.6762(5)
Rð1Þf
1186.8699(12)
1150.5393(14)
1134.9314(29)
1126.9094(219)
1118.7440(25)
1102.0056(23)
1093.4394(218)
1084.7417(1)
Pð13Þe
Pð17Þe
Pð19Þe
Pð22Þe
Pð25Þe
Pð5Þf
1066.9786(26)
1030.0497(23)
1010.9312(17)
981.5080(1)
Pð10Þf
Pð11Þf
Pð12Þf
Pð13Þf
Pð16Þf
Pð17Þf
Pð21Þf
Pð22Þf
Pð23Þf
1093.5935(37)
1084.9040(7)
1076.0865(5)
1067.1461(14)
1039.6291(214)
1030.2263(47)
991.6041(7)
Rð24Þe
1241.5506(29)
1230.7127(21)
1219.1198(215)
1296.3254(20)
1294.2283(22)
1276.8125(3)
Pð3Þe
Pð5Þe
Pð6Þe
Pð7Þe
Pð9Þe
Pð10Þe
Pð11Þe
Pð12Þe
Rð20Þe
Rð19Þe
1280.3062(225)
1276.8441(11)
1269.2771(212)
1260.8546(4)
Rð6Þe
Rð18Þe
Rð25Þf
Rð24Þf
Rð18Þf
Rð14Þf
Rð13Þf
951.2517(218)
1135.0766(244)
1118.8973(247)
1110.5927(16)
1102.1652(238)
Rð16Þe
Rð14Þe
Pð7Þf
Rð13Þe
1256.3306(16)
1251.6056(24)
1260.8008(11)
1256.2751(29)
Pð8Þf
981.7028(0)
Rð12Þe
1075.9220(212)
Pð9Þf
971.7088(26)
86SrH v ¼ 1 2 0
Rð24Þe
Rð23Þe
Rð22Þe
Rð21Þe
Rð19Þe
Rð18Þe
Rð17Þe
Rð16Þe
Rð15Þe
Rð14Þe
Rð13Þe
Rð12Þe
Pð21Þe
Pð4Þf
1294.3147(9)
Rð11Þe
Rð10Þe
Rð9Þe
Rð8Þe
Rð7Þe
Rð6Þe
Rð5Þe
Rð4Þe
Rð3Þe
Rð2Þe
Rð24Þf
Rð23Þf
Pð8Þf
1246.7605(9)
Rð22Þf
Rð21Þf
Rð20Þf
Rð19Þf
Rð18Þf
Rð17Þf
Rð16Þf
Rð15Þf
Rð14Þf
Rð13Þf
Rð12Þf
Rð11Þf
Pð13Þf
Pð14Þf
Pð15Þf
Pð16Þf
Pð17Þf
1289.4189(22)
1286.6265(27)
1283.6060(7)
Rð10Þf
Rð9Þf
1241.5603(9)
Pð9Þe
1102.0724(28)
1093.5031(25)
1084.8059(24)
1075.9834(0)
1291.9856(28)
1289.4311(214)
1286.6412(11)
1280.3919(28)
1276.9319(6)
1241.6342(23)
1236.3113(23)
1230.7954(3)
1236.2311(24)
1230.7127(7)
Pð10Þe
Pð11Þe
Pð12Þe
Pð13Þe
Pð14Þe
Pð15Þe
Pð16Þe
Pð17Þe
Pð18Þe
Pð19Þe
Pð20Þe
Pð23Þf
Rð8Þf
1280.3654(215)
1276.8995(5)
Rð7Þf
1225.0058(218)
1219.1086(21)
1213.0311(211)
1206.7717(22)
1200.3350(14)
1193.7286(28)
1165.6240(212)
1118.8139(218)
1110.5108(217)
1020.7800(18)
1011.1733(23)
1001.4644(212)
991.6576(225)
981.7505(12)
1225.0908(2)
Rð6Þf
1067.0399(27)
1057.9769(25)
1048.7991(214)
1039.5070(26)
1030.1072(219)
1020.5982(26)
1010.9853(7)
1219.1989(12)
1213.1259(1)
1273.2169(7)
Rð5Þf
1273.2574(221)
1269.3612(14)
1265.2577(28)
1260.9396(15)
1256.4184(24)
1251.6910(26)
991.4622(6)
1269.3199(22)
1265.2101(212)
1260.8884(24)
1256.3602(23)
1251.6268(6)
Rð4Þf
1206.8728(27)
1200.4396(17)
1193.8392(221)
1294.3147(9)
Rð3Þf
Rð2Þf
Pð1Þe
Pð7Þe
Pð8Þe
Pð18Þf
Pð19Þf
Pð20Þf
Pð21Þf
Pð22Þf
1291.9856(228)
1110.6621(24)
1102.2290(214)
1093.6631(29)
1084.9691(26)
1076.1488(8)
1246.6951(216)
1067.2093(26)
1058.1489(0)
1001.2741(26)
971.7547(8)
1143.0173(19)
1135.1431(21)
1127.1205(21)
1118.9622(211)
Pð9Þf
Pð5Þf
Pð10Þf
Pð11Þf
Pð12Þf
1048.9744(211)
1039.6849(0)
Pð6Þf
Pð7Þf
1030.2876(28)
88SrH
v0
0
0
0
N0
1
p0
e
e
f
v00
0
N00
0
p00
e
v0
1
1
1
N0
2
p0
e
f
v00
1
N00
1
p00
e
7.328325(0)f
14.591372(25)f
7.142377(2)f
14.268285(21)f
14.148543(1)f
1179.7891(0)
2
0
1
e
2
1
1
f
1
0
0
e
1
f
0
0
e
(continued on next page)

Table 1 (continued)
Line
Wavenumber
Line
1
Wavenumber
Line
Wavenumber
Line
1
Wavenumber
Line
1
Wavenumber
0
2
f
0
f
14.467519(22)f
0
e
0
f
1165.6634(227)
86SrH
v0
N0
p0
e
v00
N00
P00
0
2
0
1
e
14.595189(21)f
11.110987(229)f
86SrD
v0
N0
p0
e
v00
N00
p00
e
v0
N0
p0
e
v00
N00
p00
e
0
3
0
2
0
4
0
3
14.800171(3)f
88SrD
v0
0
0
N0
3
p0
e
v00
0
N00
2
p00
e
v0
0
1
N0
4
p0
f
v00
0
N00
3
p00
f
11.105232(229)f
14.792510(0)f
14.729609(24)f
14.560702(8)f
4
e
0
3
e
4
e
1
3
e
88SrD v ¼ 1 2 0
Rð1Þe
848.8145(12)g
Rð10Þe
Rð1Þf
Rð3Þf
Rð4Þf
878.2188(24)g
848.7563(1)g
855.7312(25)g
859.1261(6)g
Rð8Þf
872.0829(2)g
Pð4Þe
Pð3Þe
Pð2Þe
Pð16Þf
826.4335(3)g
Pð15Þf
Pð4Þf
Pð3Þf
Pð2Þf
780.6339(1)g
826.5010(9)g
830.3630(212)g
834.1660(4)g
Rð3Þe
855.7882(212)g
859.1799(15)g
872.1316(22)g
Rð10Þf
Pð16Þe
Pð15Þe
878.1738(24)g
776.0922(21)g
780.5517(23)g
830.2964(213)g
834.1002(10)g
776.1762(24)g
Rð4Þe
Rð8Þe
88SrD v ¼ 2 2 1
Rð4Þe
841.6044(11)g
844.8788(7)g
854.3218(210)g
860.2911(214)g
Rð17Þe
Rð21Þe
Rð4Þf
879.0299(1)g
888.1630(29)g
841.5509(14)g
844.8264(15)g
Rð8Þf
854.2738(2)g
Pð17Þe
Pð15Þe
Pð17Þf
Pð15Þf
755.2681(3)g
Rð5Þe
Rð10Þf
Rð17Þf
Rð21Þf
860.2468(26)g
878.9986(21)g
888.1382(25)g
764.1206(22)g
755.3524(27)g
764.2016(22)g
Rð8Þe
Rð10Þe
Rð5Þf
88SrD v ¼ 3 2 2
Rð6Þe
830.3966(29)g
836.5066(5)g
845.1819(212)g
853.2432(24)g
Rð15Þe
Rð17Þe
Rð26Þe
Rð6Þf
855.7882(23)g
860.6714(3)g
878.9519(1)g
830.3474(23)g
Rð8Þf
836.4617(0)g
845.1414(212)g
853.2071(3)g
855.7564(4)g
Rð17Þf
Rð26Þf
Pð7Þe
Pð5Þe
860.6415(1)g
878.9378(4)g
780.7621(8)g
788.5269(25)g
Pð7Þf
Pð5Þf
780.8316(5)g
788.5928(1)g
Rð8Þe
Rð11Þf
Rð14Þf
Rð15Þf
Rð11Þe
Rð14Þe
a
Calculated minus observed values of the line positions computed with the Dunham constants of Tables 5 and 6.
b
c
d
e
f
From Ref. [81].
From Ref. [84], see text.
From Ref. [83], see text.
From Ref. [85].
From Ref. [87], see text.
From Ref. [86].
g

A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
33
Table 2
Spectroscopic constants (in cm21) for the X2Sþ ground state of 40CaH (all uncertainties are 2s)
v
Tv
Bv
104Dv
109Hv
1013Lv
102gv
106gD;v
0
1
2
3
4
0.0
4.2286902(7)
4.1317220(39)
4.0342454(60)
3.935887(9)
1.851405(150)
1.84939(19)
1.84957(31)
1.85277(56)
1.86000(64)
6.835(31)
6.819(32)
6.774(55)
6.61(13)
5.94(9)
24.11(18)
24.3(2)
24.7(3)
24.9(9)
–
4.3566(2)
4.211(2)
4.065(4)
3.920(5)
3.777(9)
25.04(12)
25.02(13)
25.02(14)
25.1(2)
1260.12775(22)
2481.99888(30)
3665.4141(4)
4809.9464(6)
3.836122(12)
25.5(3)
Table 3
Spectroscopic constants (in cm21) for the X2Sþ ground state of 88SrH (all uncertainties are 2sÞ
v
Tv
Bv
104Dv
109Hv
1013Lv
102gv
106gD;v
0
1
2
3
4
0.0
3.6334432(16)
3.5531837(17)
3.4726241(50)
3.391531(6)
1.35664(21)
1.35436(18)
1.35330(27)
1.35282(26)
1.3558(7)
3.959(47)
3.946(38)
3.951(50)
3.61(3)
21.52(29)
21.7(2)
22.2(3)
12.3991(8)
11.9871(13)
11.580(3)
211.37(13)
211.23(12)
211.14(12)
211.3(2)
1172.80311(17)
2311.45036(29)
3415.8717(4)
–
–
11.179(5)
4485.8394(11)
3.309615(17)
3.46(8)
10.762(10)
210.7(3)
determined for these vibrational levels. The spectral lines
corresponding to e and f parity components of the same
rotational transition were fully resolved in the SrH
spectrum. However, in the CaH spectrum, the splitting
was not resolved in about one third of the R branch lines,
and the DPARFIT program was modified so that the spin-
rotation interaction constants (g and gD) were not fitted for
the unresolved lines of CaH and CaD. In order to minimize
the number of digits, the constants of Tables 2 and 3 have
been sequentially rounded and refitted [91] starting from the
highest order parameter of the highest observed vibrational
level. The new constants of the v ¼ 0 level and the
fundamental band origin ðn1!0Þ of 40CaH and 88SrH are
compared with previous studies in Table 4. The new B0 and
g0 constants are very precise because we included all the
pure rotational data [83,84,87] in our fits, and in addition to
that, we obtained a more complete set of band constants for
the v ¼ 0 to 4 levels.
The next step was to combine all the data of CaH with
CaD, and SrH with SrD in Dunham fits. The energy
þ
2
expression for a S state is different from the ordinary
Dunham expansion because of the spin-rotation interaction
term in the Hamiltonian operator. The energy expressions,
ꢀ
ꢁ
X
l;m
þ
l
m
1
2
Ev;N
¼
Yl;m v þ
½NðN þ 1Þꢀ
ꢀ
ꢁ
X
l
1
m21
1
2
ðNÞ gl;m v þ
½NðN þ 1Þꢀ
ð2Þ
2
l;m
ꢀ
ꢁ
X
l
1
m
1
2
Ev;N
¼
Yl;m v þ
½NðN þ 1Þꢀ 2 ðN þ 1Þ
2
l;m
ꢀ
ꢁ
X
l
m21
1
2
ꢁ
gl;m v þ
½NðN þ 1Þꢀ
ð3Þ
l;m
were used for e ðJ ¼ N þ 1=2Þ and f ðJ ¼ N 2 1=2Þ parities,
respectively. As formulated by Le Roy [92], the Dunham
Table 4
A comparison of some 40CaH and 88SrH constants (all values are in cm21, and all uncertainties are 2s)
n1!0
B0
104D0
109H0
1013L0
102g0
106gD;0
40CaH
This work
Ref. [84]
Ref. [83]
Ref. [82]
Ref. [81]
1260.12775(22)
4.2286902(7)
4.22868994(24)
4.2286893(13)
4.228689(44)
4.22865(100)
1.851405(150)
1.850a
6.835(31)
–
24.11(18)
4.3566(2)
25.04(12)
–
–
–
–
–
4.355530(62)
4.35668(80)
4.3569(174)
4.670(116)
–
–
1.84985(100)
1.8498(26)
1.850(26)
6.30(24)
6.27(46)
5.9b
24.84(80)
4.50(96)
–
1260.12859(110)
1260.1277(70)
88SrH
This work
Ref. [87]
1172.80311(17)
1172.80608(31)
3.6334432(16)
3.63344198(99)
1.35664(21)
1.35450(89)
3.959(47)
3.536(180)c
21.52(29)
–
12.3991(8)
211.37(13)
211.22(66)c
12.39878(63)
a
Fixed to the value taken from Ref. [81].
Fixed to Y0;3 value.
b
c
Common for v ¼ 0 and 1.

34
A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
constants of two isotopomers of the A–B molecule are
related via the following equation:
determined in a combined fit using the DPARFIT program
[90], and are compared with the constants of Petitprez
et al. [81] in Table 5. For the SrH and SrD molecules, we
combined the data of five isotopomers, and performed a
similar fit. The Dunham constants of 88SrH and 88SrD,
and the Born–Oppenheimer breakdown constants are
presented in Table 6, and compared with the previously
determined constants [85,86]. Only the constants of 40CaH
and 88SrH and the Born–Oppenheimer breakdown
parameters in Tables 5 and 6 were fitted to experimental
data, and the constants of 40CaD and 88SrD are derived
using Eqs. (4)–(6) and the constants of the corresponding
hydrides. By using the sequential rounding and refitting
technique [91], starting from the parameter with largest
relative uncertainty, we minimized the number of digits
required for 40CaH and 88SrH constants in Tables 5 and 6.
Of course, the derived Dunham constants for 40CaD and
88SrD require more digits as determined by the parameter
sensitivities [91]. No Born–Oppenheimer breakdown
correction for strontium isotopic species was required
(
)
ꢂ
ꢃ
DMAa
MAa
DMBa
MBa
m1
ma
mþl=2
Yla;m
¼
Yl1;m
þ
dAl;m
þ
dBl;m
:
ð4Þ
The dl;m’s are the Born–Oppenheimer breakdown
parameters for the atoms A and B with masses MA and
MB; and m’s are reduced masses. The index 1 is for the main
(reference) isotopomer and a is the index for the other
isotopomer(s). The gl;m constants of two isotopomers are
related by a reduced mass relationship
ꢂ
ꢃ
mþl=2
m1
ma
gal;m ¼ g1l;m
:
ð5Þ
For the CaH and CaD molecules, only one isotope of
calcium (40Ca) has been observed, and Eq. (4) becomes
simpler
ꢄ
ꢅꢂ
ꢃ
mþl=2
MD 2 MH
mCaH
mCaD
CaD
l;m
CaH
l;m
Y
¼ Y
þ
dHl;m
:
ð6Þ
MD
ðd ¼ 0Þ; and, therefore, the Dunham constants of 87SrH
Sr
l;m
and 86SrH are related to those of 88SrH by simple reduced
mass ratios, and are not shown in Table 6.
The Dunham constants of 40CaH and 40CaD, and the
Born–Oppenheimer breakdown constants ðdHl;mÞ have been
Table 5
Dunham and Born–Oppenheimer breakdown constants (in cm21) for the X2Sþ ground state of 40CaH and 40CaD (all uncertainties are 2s)
40CaH
40CaD
This work
Ref. [81]
This work
Ref. [81]
Y1;0
1298.39996(130)
219.18099(100)
4.210(31)
1298.3999(80)
219.1842(56)
4.373(172)
929.903553
29.813622
1.03831
929.9312(90)
29.8342(34)
1.605(64)
2.532(46)
2.194646(140)
23.5593(28)
0.276(44)
21.442(36)
–
Y2;0
102Y3;0
103Y4;0
Y0;1
29.426(31)
4.2770434(38)
29.66314(98)
21.486(58)
0.00(15)
29.635(174)
4.277019(138)
22.01787
2.19469905
23.548718
20.390573
0.00
102Y1;1
104Y2;1
105Y3;1
106Y4;1
104Y0;2
107Y1;2
108Y2;2
108Y3;2
109Y0;3
1011Y1;3
1011Y2;3
1013Y0;4
1014Y1;4
102g0;1
103g1;1
106g2;1
106g0;2
dH1;0
29.6894(40)
1.051(164)
27.665(194)
–
27.473(130)
21.85266(20)
2.42(26)
21.00698
20.48831
0.45543
21.8471(112)
4.29(38)
20.48549(94)
0.807(70)
22.04(20)
–
1.30(76)
215.15(150)
–
0.17517
22.429(81)
6.814(38)
20.234354
0.918178
0.7429
5.900(184)
0.795(24)
–
7.7(31)
–
23.58(36)
24.0(2)
23.0(13)
–
20.24731
20.27633
20.14839
2.270122
20.52309
22.37
–
–
–
–
–
4.4280(9)
4.391(140)
21.719(146)
–
2.251(72)
20.631(54)
–
21.425(18)
29.0(43)
25.0(1)
84.5(26)
21.314
2.22(72)
0.6501(53)
0.078(6)
dH2;0
102dH3;0
103dH4;0
dH0;1
102dH1;1
104dH0;2
22.765(240)
3.5(3)
0.007686(3)
20.0085(7)
20.0104(7)

A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
35
Table 6
Dunham and Born–Oppenheimer breakdown constants (in cm21) for the X2Sþ ground state of 88SrH and 88SrD (all uncertainties are 2s)
88SrH
88SrD
This work
Ref. [85]
This work
Ref. [86]
Y1;0
1207.03454(140)
217.16492(110)
4.030(35)
1206.8912(30)
858.896638
28.678401
1.34104
858.8547(28)
Y2;0
217.02566(186)
21.162(30)
28.63901(168)
20.056(26)
102Y3;0
103Y4;0
Y0;1
26.505(38)
3.6734952(35)
28.00602(78)
20.882(56)
0.00(15)
–
21.665827
1.86067025
22.883574
20.225866
0.00
–
3.673447(44)
1.860651(80)
102Y1;1
104Y2;1
105Y3;1
106Y4;1
104Y0;2
107Y1;2
108Y2;2
108Y3;2
28.0132(32)
0.223(182)
22.8822(26)
20.304(58)
24.02(30)
–
–
24.456(160)
21.35785(23)
2.37(16)
20.57746
20.348875
0.43174
–
21.3505(28)
0.0a
20.3506(24)
1.29(84)
1.60(69)
–
0.20735
23.17(138)
–
21.35(8)
3.955(52)
–
20.124452
0.512531
0.27656
109Y0;3
3.03(38)
0.91(50)
11
10
Y
1;3
3.0(17)
–
–
1011Y2;3
13
22.01(29)
21.5(3)
21.8(8)
–
20.13181
20.09837
20.08397
6.37873
–
10
Y
0;4
–
–
1014Y1;4
102g0;1
103g1;1
106g2;1
106g0;2
107g1;2
dH1;0
dH2;0
102dH3;0
dH0;1
–
–
12.605(2)
12.622(84)
6.376(90)
24.131(19)
9.0(44)
24.062(76)
–
21.48711
2.3
21.476(60)
–
211.4(2)
1.3(2)
211.6(32)
–
22.919
0.2368
22.60(146)
–
0.6987(38)
0.0311(31)
20.61(7)
0.006753(5)
20.0084(7)
20.009(1)
102dH1;1
104dH0;2
a
Fixed to zero.
4. Discussion
parameters required for the vibrational energy ðdHl;0Þ is equal
to the number of observed vibrational intervals in the CaD
[81] and SrD [86] infrared spectra. Therefore, the simple
reduced mass ratio is not appropriate for the Dunham
constants representing the vibrational energy ðYl;0Þ in this
range of the potential well. However, fewer correction
parameters were required for the rotational and centrifugal
distortion constants (Yl;1 and Yl;2Þ: The reduced mass
relationship in Eq. (5) for the spin-rotation interaction
constants ðgl;mÞ was satisfactory, and no correction was
required for those constants.
Having a more complete set of data for v ¼ 0 to 4 of
40CaH and 88SrH, we were able to determine a more
reliable set of band constants for these vibrational levels
compared to the previous work [81–84,87]. The new
experimental data allowed us to determine higher order
Dunham constants for the ground states of CaH and SrH,
and by including the pure rotational data we were able to
determine the equilibrium rotational constants ðBe < Y0;1
Þ
with high precision. Using the Be values of 40CaH and
88SrH, we calculated the equilibrium bond distances ðreÞ
Although BeH2 and MgH2 molecules are linear [6,7,9],
theoretical calculations have predicted bent structures for
SrH2 and BaH2 [1–3]. In the case of CaH2, the results from
different studies are not consistent with each other. Three ab
initio calculations predicted a linear structure for CaH2 [1,3,
5], and in another study by Bytheway et al. [2] the H–Ca–H
bond angle was calculated to be 157 degrees. The infrared
spectrum of CaH2 trapped in krypton and xenon matrices at
12 K was recorded by Xiao et al. [93], and assuming a bent
structure for this molecule, they assigned a very weak
absorption band to the symmetric stretching mode of CaH2.
˚
˚
to be 2.0023603(9) A for CaH and 2.1460574(10) A for
SrH. The Y3;1 constants in both CaH and SrH are very
small (smaller than their uncertainties), but the higher
order Y4;1 constants are larger. In the sequential rounding
and refitting process, the Y3;1 constants have been
rounded to zero for both CaH and SrH.
The Born–Oppenheimer breakdown constants for hydro-
gen atom ðdHl;mÞ are large, which is expected for diatomic
hydrides with small reduced masses. In fact, for both CaH
and SrH, the number of Born–Oppenheimer breakdown

36
A. Shayesteh et al. / Journal of Molecular Structure 695–696 (2004) 23–37
Table 7
A comparison of bond lengths and atomization energies of alkaline earth hydrides (2s uncertainties are reported for all experimental values)
˚
re (A) M–H
˚
re (A) H–M–H
Metal
Ref.
Ref.
Atomization energy
of MH2(g) (kcal/mol)
Ref.
DE (kcal/mol) M(g)
þ H2(g) ! MH2(g)
MH2(g) Observed?
Be
Mg
Ca
Sr
1.342436(2)
1.7297612(9)
2.0023603(9)c
2.146057(1)c
2.231882(2)
[8]
1.326407(6)
[1.703327(6)]b
2.03
[7]
[9]
[1]
[1]
[1]
140.9
98.6
84.2d
–
[97]
[98]
[5]
237.6a
þ4.7a
þ19.1a
–
Yes
Yes
No
[95]
2.18
No
Ba
[96]
2.27
–
–
No
a
Calculated using the dissociation energy of H2 (103.3 kcal/mol) from Ref. [94].
r0 value from Ref. [9].
b
c
d
This work.
A slightly different value (81.3 kcal/mol) is reported in Ref. [4].
One of our goals in this work was to record the vibration–
rotation emission spectra of gaseous CaH2, SrH2 and BaH2
to determine their structures. Although we observed the
vibration–rotation transitions of CaH, SrH and BaH with
high signal-to-noise ratios, no metal dihydride was found in
the spectra.
obtained in combined isotopomer fits. One of the goals in
this work was to obtain the vibration–rotation emission
spectra of CaH2(g), SrH2(g) and BaH2(g), but none of these
species were found.
We have compared molecular properties of alkaline earth
hydrides in Table 7 to investigate the reason why we could
not observe CaH2, SrH2 and BaH2 in the gas phase. It can be
seen in Table 7 that the M–H bond distances change very
slightly from MH(g) to MH2(g) because the unpaired
electron of the metal monohydride is in a non-bonding
molecular orbital. Furthermore, as the M–H bond distance
increases from Be to Ca, the total atomization energy of
MH2(g) decreases (Table 7). The dissociation energy of
H2(g) is 103.3 kcal/mol [94], and therefore the overall
reaction
Acknowledgements
This work was supported by Natural Sciences and
Engineering Research Council (NSERC) of Canada. We
thank R. J. Le Roy for help with the DPARFIT program.
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