50
The European Physical Journal D
of approximation, which explicitly takes into account the
resonance interaction.
The (ν1/ν3) stretching dyad of stannane was reinves-
tigated by Tabyaoui et al. [24,25] near 1900 cm−1, em-
ploying a monoisotopic sample, 116SnH4, by which am-
biguities caused by mutual blending of lines, belonging
to different isotopic species could be circumvented. They
have recorded and analysed the FTIR and high-resolution
Stimulated Raman spectra. A simultaneous analysis of the
Raman, infrared and microwave data using a Hamiltonian
developed to the sixth order for the (ν1/ν3) dyad enabled
them to determine 4 parameters for the ν1 band, 17 pa-
rameters for the ν3 band and 6 interaction parameters.
The line transitions were assigned up to J = 14. They
have shown that for high J values (J > 14), a perturba-
tion appears due to an interaction between the stretching
dyad (ν1/ν3) and the second overtone of bending modes
(3ν2, 2ν2 + ν4, ν2 + 2ν4, 3ν4). In the fit of the Hamiltonian
parameters, the ground state parameters were fixed to the
values determined by Brunet et al. [1], where the tenso-
rial ones are close to the values determined by Ohshima
et al. [21,22].
Fig. 1. Experimental spectrum of monoisotopic stannane
116SnH4.
116SnH4 was investigated too by Brunet et al. [1] who
analysed the FTIR spectrum of the (ν2/ν4) dyad using a
sixth order Hamiltonian. The analysis of the infrared tran-
sitions allowed them to determine 10 ground state param-
eters, 9ν2 parameters, 17ν4 parameters and 18 interaction
parameters.
an aqueous HCl/HNO3 mixture, with an aqueous solu-
tion of NaBH4 (3%) in vacuum (50–80 mbar). Gaseous
116SnH4 evolved was collected at −196 ◦C and purified by
repeated fractional condensation using a standard vacuum
line, yield ∼90%.
FTIR spectra were recorded at Giessen in the
490–980 cm−1 range with a Bruker 120 HR spectrome-
ter equipped with a Ge/KBr beam splitter and a Cu:Ge
detector. The resolution, trapezoidal apodization, was
2.0 × 10−3 cm−1; the Doppler width at 700 cm−1 is ap-
prox. 0.7 × 10−3 cm−1. The actual width of weak lines
(FWHM) was ∼2.1×10−3 cm−1. A cell of 18.7 cm length
equipped with KBr windows was employed, and a pres-
sure of 1 mbar chosen. A total of 50 scans were co added.
Calibration was performed with N2O lines [28]; relative to
Halonen et al. [26] have analysed the FTIR spectrum
of the (2000, A1/F2) stretching vibrational band system
of 116SnH4 up to J = 20 and refined 21 Hamiltonian pa-
rameters in a local mode model. Also, Halonen et al. [27]
have analysed the FTIR spectra of the (1000, A1/F2),
(2000, A1/F2), (3000, A1/F2) vibrational band systems
for 120SnD4. They have made a rotational analysis of the
spectra. The local mode relations obtained confirm that
vibrational energy localization takes place in the second
stretching vibrational overtone of deuterated stannane.
Recently, we have made an analysis of the FTIR spec-
trum of the monoisotopic stannane in the 1400 cm−1 re-
gion corresponding to the bending triad [2]. The results
obtained enabled us to assign directly most observed tran-
sitions to the hot band {bending triad} minus {bending
dyad} near 700 cm−1. We have then included these tran-
sitions in the fit of the Hamiltonian parameters. The
simultaneous analysis of infrared data corresponding to
both hot band and bending triad enabled us to deter-
mine 26 Hamiltonian parameters for the 2ν2 and (ν2 +
these lines it is better than 1.0 × 10−4 cm−1
.
The medium-resolution spectrum showed in Figure 1
was recorded with a Nicolet 7199 FTIR spectrometer em-
ploying a resolution of 0.05 cm−1
.
3 Theory
The transformed vibrational-rotational Hamiltonian for
tetrahedral molecules developed by Champion and
Pierre [29–31] is especially well adapted for vibrational ex-
trapolation. Vibrational operators are expressed in terms
of tensor products of creation and annihilation elementary
operators in such a way that each term of the Hamiltonian
expansion corresponds to a given vibrational state or set
of quasi-degenerate vibrational states. According to this
scheme, the completely transformed Hamiltonian for the
vibrational states taken into account in this work, can be
written as
ν4) bands [2]. The standard deviation was 1.5×10−3 cm−1
.
In this work, we present for the hot band {bending
triad} minus {bending dyad}, the assignments realized up
to J = 9 and the results obtained for this hot band during
the analysis of the bending triad (2ν2, ν2 + ν4, 2ν4).
2 Experimental details
Monoisotopic stannane, 116SnH4, was prepared by re-
acting a solution containing SnCl26− (1 mg Sn/ml), ob-
tained by dissolving 116Sn (98% 116Sn, Oak Ridge) in
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H = H
+
H
+
H
+
H
. (1)
{νs+νsꢀ }
{GS}
{νs}
{2νs}
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s
s