Kinetics of Pb reactions with N2O, Cl2, HCl, and O2 at high temperatures

Article abstract of DOI:10.1021/jp000209z

The title reactions of ground-state lead atoms have been studied in isolation in an HTFFR (high-temperature fast-flow reactor) at pressures in the 10-150 mbar range. Pb consumption rate coefficients were determined using atomic resonance absorption spectr

Full text of DOI:10.1021/jp000209z

J. Phys. Chem. A 2000, 104, 5517-5524
5517
Kinetics of Pb Reactions with N2O, Cl2, HCl, and O2 at High Temperatures
Biljana Cosic and Arthur Fontijn*
High-Temperature Reaction Kinetics Laboratory, The Isermann Department of Chemical Engineering,
Rensselaer Polytechnic Institute, Troy, New York 12180-3590
ReceiVed: January 14, 2000; In Final Form: March 29, 2000
The title reactions of ground-state lead atoms have been studied in isolation in an HTFFR (high-temperature
fast-flow reactor) at pressures in the 10-150 mbar range. Pb consumption rate coefficients were determined
using atomic resonance absorption spectrometry at 217.0 and 283.3 nm. The following results, in cm3
molecule-1 s-1, have been obtained: Pb + N2O, k(650-1205 K) ) 1.8 × 10-10 exp(-8948 K/T); Pb + Cl2,
k(530-1165 K) ) 2.3 × 10-10 exp(-718 K/T); Pb + HCl, k(1090-1320 K) ) 8.2 × 10-10 exp(-17233
K/T). The precision limits vary somewhat between these measurements; the estimated 2σ accuracy limits are
all about (25%. The Pb + HCl result suggests that D0(Pb-Cl) ) 318 ( 31 kJ mol-1. In contrast to the
above homogeneous processes, the observations on the O2 reaction indicate the dominance of heterogeneous
reactions. It is speculated that these lead primarily to PbO2 below 1000 K and to PbO above 1000 K.
Pb + HCl f PbCl + H
∆H298 ) 130 ( 50 kJ mol-1 12
Introduction
(3)
The presence of metals in many high-temperature environ-
ments, such as waste incineration, coal combustion, and many
industrial processes, can lead to toxic emissions as particles and
gases. Sorbents have been developed to clean flue gases,1 but
their performance is critically dependent on the chemical form
of the metals. Influencing the chemistry in a favorable direction
for this approach to work again requires knowledge of the metal
species kinetics. The removal of lead from gasoline notwith-
standing, Pb remains one of the major elements of environmental
concern.2 Data on the kinetics of the formation of lead oxides
and chlorides at combustion temperatures are much needed.3
Most of the available information on ground state Pb(63P0)
reactions comes from the work of Husain and co-workers, who
studied a number of reactions at room temperature4-6 and also
determined the temperature dependence of the reactions with
several alkyl chlorides and SF6 (594-819 K),7 alkyl bromides
(640-760 K),8 and N2O (648-783 K).9 Husain and Littler
determined rate coefficient expressions for the third-order
reactions with NO and O2 between 290 and 570 K,10 which
show a negative activation energy. Their experiments were
carried out in a static tubular photochemical reactor. For Pb +
O2 + M Ryason and Smith,11 using a quartz fast-flow reactor,
obtained k(870 K) ) 9.4 × 10-33 cm6 molecule-2 s-1, somewhat
higher than extrapolation of Husain’s results would predict.
However, at that temperature the reaction was thought to be
50% due to wall reactions, which totally dominated at higher
temperatures (960 and 992 K).
Pb + O2 f products
(4)
The inclusion of reaction 1 allows a direct comparison in an
overlapping temperature interval with the results of Husain and
Sealy9 obtained by a radically different technique. Also, it
provides an additional wide temperature range measurement of
an activation barrier for a group 14 element, to allow future
development of the SECI approach for calculating such
barriers.13-15 This approach has previously been applied to the
N2O reactions of metal atoms of the first three main groups of
the periodic table, as well as to some diatomic metal oxides
and halides with various oxidants. The measurements on reaction
3 have allowed a reevaluation of the heat of that reaction, as
well as of reaction 2, from the above JANAF values. The O2
results confirm the importance of heterogeneous processes in
its reaction with Pb atoms.
Technique
The kinetic measurements were made in a high-temperature
fast-flow reactor (HTFFR) using atomic resonance absorption
spectrometry (ARAS). The apparatus, procedures, and data
analysis methods have been described extensively in many
earlier publications.15-18 The reaction tube is heated radiatively
by SiC resistance heating elements inside a water-cooled steel
vacuum housing. Atomic Pb was generated by evaporation of
solid lead from an alumina crucible. The vapor was entrained
in a stream of bath gas and reacted with an oxidant, introduced
through a movable inlet downstream from the Pb source. Except
where otherwise mentioned, an industrial-grade quartz reaction
tube and N2 bath gas were used. Temperature was measured
with a retractable Pt-Pt/13% Rh thermocouple. Pressure
measurements were obtained downstream from the reaction zone
using an MKS Baratron pressure transducer. Gas flow rates were
determined by calibrated Hastings-Teledyne mass-flow control-
lers. The Pb resonance radiation was generated by a Buck
Scientific hollow cathode lamp, and the absorption was mea-
sured with an Oriel monochromator equipped with a Thorn EMI
Here we report on four reactions of ground state lead atoms
studied in a high-temperature fast-flow reactor (HTFFR) at
temperatures in the range encountered in incinerators (≈700-
1500 K):
Pb + N2O f PbO + N2
Pb + Cl2 f PbCl + Cl
∆H298 ) -207 ( 7 kJ mol-1 12
(1)
∆H298 ) -60 ( 50 kJ mol-1 12
(2)
* Corresponding author. E-mail:fontia@rpi.edu.
10.1021/jp000209z CCC: $19.00 © 2000 American Chemical Society
Published on Web 05/19/2000

5518 J. Phys. Chem. A, Vol. 104, No. 23, 2000
Cosic and Fontijn
9831QA photomultiplier tube, the output of which was trans-
ferred to a Keithley 614 electrometer. The transitions λ ) 217.0
nm (Pb(63D1) r Pb(63P0)) or λ ) 283.3 nm (Pb(73P1) r
Pb(63P0)) were observed.
allowing a combined expression
k1(648-1205 K) ) 1.80 × 10 -10
exp(-8948 K/T) cm3 molecule-1 s-1 (7)
The gas concentrations were chosen such that [Pb] ,
[oxidant],[bath gas], providing for pseudo-first-order conditions
in the reaction zone. Rate coefficient measurements were per-
formed in the stationary inlet mode18 with reaction zone lengths
of 10 or 20 cm. Individual rate coefficients, ki, were obtained
Adding their individual data points to the present set, we
arrive at accuracy limits equal to those of eq 5.
The pressure independence is in accord with the suggested
abstraction reaction 1. These results may be compared to those
of the group 14 elements Sn and Ge with N2O, the temperature
dependence of which was studied most extensively in previous
HTFFR experiments to yield, respectively21,29
from the slope of linear plots of ln [Pb]relative vs [oxidant].19
A
weighted linear regression was used to determine ki and σki.20
Typically, five oxidant concentrations, providing variation by
a factor of 5, were used. The chemicals used were Pb granules
(30 mesh, 99.5+%) from Aldrich; N2 (99.995%) and Ar
(99.998%) bath gases both from the liquid, from Praxair; N2O
(99.99%), Cl2 (0.029% in Ar), and O2 (99.99%), all from
Matheson; and HCl (99.995%) from Spectra Gases Inc. These
oxidants flowed through Drierite (CaSO4) drying towers.
Sn + N2O f SnO + N2
∆H298 ) -365 kJ mol-1 (8)
k8(300-950 K) ) 8.9 × 10-13
exp(-2260 K/T) cm3 molecule-1 s-1
Ge + N2O f GeO + N2
∆H298 ) -492 kJ mol-1 (9)
Results and Discussion
The Pb + N2O Reaction. The temperature and pressure
ranges covered in this study were 660-1205 K and 10-85
mbar, respectively. The low-temperature limit was determined
by the small value of the rate coefficients. The high-temperature
limit was imposed by thermal decomposition of nitrous oxide.
In previous HTFFR work,21,22 with Ar as bath gas, that limit
was found to be around 1000 K. This study showed that with
N2 as bath gas, which helps stabilize N2O by reducing its
equilibrium dissociation,23 the temperature limit could be
increased to 1200 K.24 The other reaction conditions including
pressure and correspondingly total concentration [M], maximum
N2O concentration [N2O]max, observed reaction zone length z,
average velocity Vj, and initial Pb absorption were also varied;
their values are listed in Table 1 together with the individual
rate coefficients ki measured. Residual analysis based on
examination of [k(T) - ki]/k(T) plots showed that the rate
coefficients were independent of any of the listed variables and
the absorption line used. The data are well fitted by a weighted
linear regression25,26 of the form k(T) ) A exp(-E/T) to yield
k9(475-920 K) ) 1.7 × 10-11
exp(-470 K/T) cm3 molecule-1 s-1
3
The ground states of these group 14 elements are P0, and
their reactions with N2O are spin-forbidden for formation of
ground state products
Z(3P0) + N2O(X1Σ) f ZO(X1Σ) + N2(X1Σ)
(Z ) Pb, Sn, Ge) (10)
but allowed for production of triplet ZO. Spin conservation does
not have to play a major role for as heavy an element as Pb,
and reaction 1 is insufficiently exothermic12,30 to populate a PbO
triplet level. Indeed the preexponential of k1 is of the same
magnitude as that measured at similar temperatures for the spin-
allowed N2O reactions with Cr,31 Cu,32 and Al.13
The preexponentials of the Sn and Ge reactions are consider-
ably smaller. These reactions, as witnessed by their chemilu-
minescence, are known to lead in part to triplet states.21,29 They
have been extensively discussed and compared to each other29
and are thought to proceed through intermediate formation of
Sn(3P1) and Ge(3P1), respectively. Indeed their activation ener-
k1(660-1205 K) ) 1.76 × 10-10
exp(-8921 K/T) cm3 molecule-1 s-1 (5)
3
gies compare well to the P0-3P1 energy splits of 20 and 6.7
kJ mol-1, respectively. This, in addition to the sequence of their
reaction exothermicities,9 has been advanced29 as the reason for
the greater activation energy for Sn compared to Ge. The lower
preexponential of Sn relative to Ge has been attributed to its
reaction being more selective in producing ZO to a major degree
This activation energy is equivalent to 74 kJ mol-1. The
calculated variances and covariance are σA2 ) 3.13 × 10-2 A2,
σE ) 2.50 × 104, and σAE ) 2.76 × 10 A, corresponding to
2
(2σk precision limits varying from 14% at 660 K to 11% at
1205 K. Allowing (20% for possible systematic errors and
(10% for the uncertainty associated with the flow profile factor
η1,4,18,27,28 yields (2σk confidence limits varying from 27% to
25%.
3
in one state, a Σ, resulting in a lower entropy of activation.29
The Pb(63P0-63P1) split is 93.5 kJ mol-1, considerably more
than the Pb + N2O activation energy. This makes it likely that
this reaction proceeds directly from 63P0 atoms and does not
go through intermediate 63P1 formation. The equilibrium
population of Pb(63P1) also should be negligible at the temper-
atures investigated. Thus eq 10 appears to correctly represent
the reaction path for the Pb + N2O reaction studied, allowing
for intermediate complex formation.
The reaction of Pb with N2O was previously studied by
Husain and Sealy9 in the 648-783 K temperature interval, at
pressures around 100 mbar. They used time-resolved ARAS
following the pulsed irradiation of PbBr2 and determined
k1(648-783 K) ) 6 × 10-11 exp(-8179 (
1203 K/T) cm3 molecule-1s-1 (6)
The Pb + Cl2 Reaction. The rate coefficient measurements
spanned the 530-1165 K temperature range. The lower tem-
perature limit is due to the heating of the source used for Pb
evaporation. The upper temperature limit was set by thermal
dissociation of Cl2, which became significant only at the
temperatures above 1200 K. Residual analyses were, as above,
performed to check the dependence of the rate coefficients on
There is a misprint in their Table 1, where the rate coeffi-
cients were assigned the power 10-11 instead of 10-16. That
the latter was meant can be concluded from eq 6. In Figure
1 the data sets are compared. The agreement is excellent,

Pb Reactions with N2O, Cl2, HCl, and O2
J. Phys. Chem. A, Vol. 104, No. 23, 2000 5519
TABLE 1: Summary of Rate Coefficient Measurements of Pb + N2Oa
[M],
[N2O]max
,
reaction zone
length, cm
initial Pb
absorption, %
ki ( σki,
T, K
P, mbar
1017 cm-3
1015 cm-3
Vj, m s-1
cm3 molecule-1 s-1
722
725
729
904
987
988
978
971
799
784
762
892
881
880
752
749
693
700
700
675
673
1205
1201
1191
1162
1160
1075
1074
1064
1051
892
903
898
906
840
833
847
743
743
56.0
39.8
39.8
70.6
23.4
23.4
65.5
65.6
34.6
34.8
76.8
17.8
40.0
40.0
40.1
85.9
68.9
35.6
48.2
48.2
69.7
10.2
12.0
11.0
19.5
19.6
31.1
17.3
41.6
41.6
30.4
30.4
57.4
52.4
52.5
18.3
71.4
49.2
49.2
49.2
49.5
18.1
33.8
27.7
37.6
21.8
22.1
22.1
32.8
28.4
28.4
28.4
5.62
3.97
3.95
5.65
1.72
1.72
4.85
4.90
3.14
3.21
7.30
1.44
3.29
3.29
3.86
8.31
7.20
3.68
4.99
5.18
7.50
0.62
0.72
0.67
1.21
1.22
2.10
1.16
2.83
2.87
2.47
2.44
4.63
4.19
4.53
1.59
6.10
4.79
4.79
4.81
3.27
1.20
3.69
3.03
3.35
1.51
1.54
1.54
2.71
2.45
2.09
1.98
37.2
32.2
32.0
22.5
8.5
9
11
12
8
26
26
9
20
20
20
20
20
10
10
20
20
20
20
20
10
10
20
20
20
20
20
20
20
20
20
20
20
10
20
20
10
10
20
20
20
20
20
20
10
20
20
20
10
10
20
20
20
20
20
20
20
20
20
20
39
36
36
37
42
45
23
45
46
36
43
48
39
37
39
41
28
32
32
30
26
31
26
22
47
52
32
43
30
26
39
40
30
33
36
44
21
54b
40b
38b
56b
52b
42
40
51b
49b
17
55b
24
53b
33b
57b
(6.41 ( 0.44) × 10-16
(1.01 ( 0.07) × 10-15
(9.35 ( 0.62) × 10-16
(9.46 ( 0.57) × 10-15
(2.29 ( 0.19) × 10-14
(2.10 ( 0.17) × 10-14
(1.24 ( 0.09) × 10-14
(1.41 ( 0.09) × 10-14
(2.59 ( 0.18) × 10-15
(2.43 ( 0.17) × 10-15
(1.23 ( 0.07) × 10-15
(9.25 ( 0.87) × 10-15
(6.37 ( 0.46) × 10-15
(6.38 ( 0.45) × 10-15
(1.45 ( 0.10) × 10-15
(1.08 ( 0.06) × 10-15
(3.58 ( 0.21) × 10-16
(6.48 ( 0.51) × 10-16
(4.60 ( 0.34) × 10-16
(2.46 ( 0.17) × 10-16
(2.40 ( 0.15) × 10-16
(1.31 ( 0.20) × 10-13
(9.25 ( 1.35) × 10-14
(9.67 ( 1.38) × 10-14
(8.17 ( 0.78) × 10-14
(6.22 ( 0.59) × 10-14
(5.32 ( 0.40) × 10-14
(6.30 ( 0.60) × 10-14
(3.92 ( 0.30) × 10-14
(3.87 ( 0.30) × 10-14
(7.18 ( 0.51) × 10-15
(8.39 ( 0.60) × 10-15
(7.47 ( 0.45) × 10-15
(7.94 ( 0.51) × 10-15
(3.44 ( 0.23) × 10-15
(4.77 ( 0.44) × 10-15
(3.54 ( 0.25) × 10-15
(1.11 ( 0.08) × 10-15
(1.22 ( 0.08) × 10-15
(1.37 ( 0.09) × 10-15
(4.33 ( 0.33) × 10-14
(6.48 ( 0.71) × 10-14
(3.03 ( 0.24) × 10-16
(2.42 ( 0.19) × 10-16
(3.35 ( 0.27) × 10-15
(4.37 ( 0.44) × 10-14
(3.07 ( 0.26) × 10-14
(3.56 ( 0.32) × 10-14
(7.84 ( 0.68) × 10-15
(4.08 ( 0.30) × 10-15
(2.26 ( 0.20) × 10-14
(2.91 ( 0.21) × 10-14
8.5
23.9
17.2
15.5
23.2
52.7
10.4
23.8
23.8
27.9
48.7
41.8
29.6
47.2
49.0
71.0
2.0
2.7
2.8
5.5
8.1
6.8
3.7
6.6
6.7
11.5
11.4
13.3
12.1
21.2
10.9
24.3
34.4
34.4
34.5
5.1
9
14
14
6
31
14
14
12
5
6
12
8
8
5
80
81
80
41
41
23
42
17
17
19
20
10
11
11
30
9
10
10
9
741
1095
1094
663
661
813
1048
1043
1043
877
839
982
14
38
12
12
14
30
29
29
17
18
22
23
5.9
29.8
30.1
16.5
7.4
3.9
3.9
13.4
12.1
10.4
9.8
1036
a The measurements are reported in the sequence in which they were obtained. b The 217.0 nm absorption line was used in these experiments.
In all other experiments the 283.3 nm line was used.
the reaction parameters. Originally, the pressure range used was
10-65 mbar; however, the data at the highest pressures were
systematically lower than those from 20 to 50 mbar, and those
at the lowest pressures were systematically higher. Only data
in this central range, which are independent of the reaction
parameters, were retained; cf. Table 2. Because of this problem
a few further factors were considered. First, Cl2 has a wide
absorption continuum extending from the visible region to 250
nm with a maximum around 330 nm,30 which could have
affected the 283 nm measurements. However, in experiments
without Pb no absorption by Cl2 could be observed at the
concentrations used. [Cl2] several orders of magnitude higher
were required to begin to observe absorption. The data may be
seen to be independent of the absorption line used; cf. also
Figure 2. Second, it was investigated if the flow profile factor
could have influenced the results at the extremes of pressure.
However, residual plots of the rate coefficients versus the
Reynolds number Re ) (2VjaP)/(νRT) 33 of the individual
experiments showed no dependence. Thus this is not a factor.
The data were fitted by a weighted linear regression, as above,
to yield
k2(530-1165 K) ) 2.28 × 10 -10
exp(-718 K/T) cm3 molecule-1 s-1 (11)
where the 718 K corresponds to 5.97 kJ mol-1. The variances
and covariance are σA ) 4.21 × 10-3 A2, σE ) 2.76 × 103,
and σAE ) 3.33 A. The (2σk precision limits are determined
to be 8% at 534 K and 5% at 1186 K yielding confidence limits
of 24% and 23%.
2
2

5520 J. Phys. Chem. A, Vol. 104, No. 23, 2000
Cosic and Fontijn
Figure 2. Arrhenius plot of the Pb + Cl2 rate coefficients: (b)
measurements taken at 217.0 nm; (O) measurements taken at 283.3
nm; (s) best fit to the measurements (eq 11).
Figure 1. Arrhenius plot of the Pb + N2O rate coefficients: (O) mea-
surements taken at 283.3 nm; (b) measurements taken at 217.0 nm;
(]) Husain and Sealy; (s) best fit to the joint measurements (eq 7).
the relatively weakly bound product PbCl (see below). The rate
-16
coefficients fall within the (1-20) × 10
cm3 molecule-1
The large preexponential and rather small activation energy
of eq 11 are typical for exothermic Cl2 reactions with metal
atoms. Several have thus far been measured over a range of
temperatures, i.e., those with Al,34 Cr,31 Mg,35 Ti,36 and Cu.37
All these are thought to proceed by abstraction, which is also
thought to be the dominant mechanism for Pb; cf. eq 2.
s-1 range, which largely is lower than could be achieved in
previous HTFFR studies. Accordingly, they show a larger scatter
than those from the N2O and Cl2 reactions; cf. Figure 3. The
residual analysis shows the data to be independent of the reaction
parameters, Table 3. Linear regression yields
The Pb + HCl Reaction. The reaction rates for this system
could only be obtained in the narrow temperature range 1090-
1320 K. At lower temperatures the rates were too low to be
measurable, and above about 1320 K the drop in the observed
reaction rate coefficients indicated thermal decomposition of
k3(1090-1320 K) ) 8.22 × 10-10
exp(-17233 K/T) cm3 molecule-1 s-1 (12)
where 17233 K is equivalent to 143 kJ mol-1. The variances
a
TABLE 2: Summary of Rate Coefficient Measurements of Pb + Cl2
[M],
[Cl2]max
,
reaction zone
length, cm
initial Pb
absorption, %
ki ( σki,
T, K
P, mbar
1017 cm-3
1012 cm-3
Vj, m s-1
cm3 molecule-1 s-1
742
742
742
741
736
1017
1020
1017
1018
1018
1019
1019
534
742
738
738
737
1081
1080
1079
1089
622
646
658
52.0
52.0
34.6
34.7
34.4
46.9
46.9
46.9
28.5
28.7
28.7
28.7
50.9
30.9
36.5
36.5
36.1
34.5
34.2
34.1
48.7
27.7
44.5
23.1
41.4
52.0
37.5
30.8
49.5
24.9
29.4
22.8
48.2
35.9
21.0
41.7
5.08
5.08
3.37
3.39
3.39
3.34
3.33
3.34
2.03
2.04
2.04
2.04
6.91
3.02
3.58
3.58
3.55
2.31
2.30
2.29
3.24
3.22
4.87
2.94
4.46
5.97
4.11
3.84
7.12
3.28
2.48
1.92
4.13
2.28
1.52
3.06
2.63
5.06
3.36
5.28
1.76
1.41
3.32
3.33
2.02
3.92
3.92
3.92
2.91
6.80
10.0
6.87
3.53
5.17
2.67
1.12
1.59
7.11
6.59
3.40
2.13
2.55
1.82
1.60
2.99
1.59
2.88
5.93
4.45
2.57
3.09
3.41
12
13
19
19
19
19
19
19
31
31
31
31
9
18
18
18
18
24
24
24
17
17
12
24
19
12
25
31
10
24
27
47
12
26
46
22
20
10
10
10
20
20
10
10
10
10
10
10
20
20
10
10
10
20
20
20
20
20
20
20
20
10
20
20
20
20
20
20
20
20
10
20
25
(9.53 ( 0.60) × 10-11
(7.35 ( 0.48) × 10-11
(9.99 ( 0.72) × 10-11
(1.02 ( 0.08) × 10-10
(1.18 ( 0.08) × 10-10
(1.58 ( 0.10) × 10-10
(1.14 ( 0.08) × 10-10
(1.20 ( 0.09) × 10-10
(1.65 ( 0.13) × 10-10
(1.59 ( 0.13) × 10-10
(1.47 ( 0.12) × 10-10
(1.49 ( 0.12) × 10-10
(7.30 ( 0.68) × 10-11
(8.26 ( 0.80) × 10-11
(1.17 ( 0.08) × 10-10
(1.16 ( 0.09) × 10-10
(1.10 ( 0.09) × 10-10
(9.68 ( 0.70) × 10-11
(1.14 ( 0.09) × 10-10
(9.16 ( 0.67) × 10-11
(8.06 ( 0.55) × 10-11
(4.39 ( 0.35) × 10-11
(9.35 ( 1.02) × 10-11
(1.11 ( 0.20) × 10-10
(9.33 ( 0.95) × 10-11
(8.88 ( 0.99) × 10-11
(1.07 ( 0.10) × 10-10
(1.23 ( 0.11) × 10-10
(6.58 ( 0.58) × 10-11
(6.23 ( 0.60) × 10-11
(9.69 ( 0.81) × 10-11
(1.22 ( 0.10) × 10-10
(5.83 ( 0.49) × 10-11
(1.10 ( 0.10) × 10-10
(1.51 ( 0.12) × 10-10
(1.17 ( 0.10) × 10-10
25b
33b
27b
33b
34b
30b
30b
37b
31b
61
59b
23b
62b
48b
57b
67b
49b
46b
46
32b
43b
28
23b
33b
25b
31b
34b
39
673
790
803
804
591
566
889
870
45b
39b
38b
40b
45b
45b
35b
685
1163
965
951
a The measurements are reported in the sequence in which they were obtained. b The 217.0 nm absorption line was used in these experiments.
In all other experiments the 283.3 nm line was used.

Pb Reactions with N2O, Cl2, HCl, and O2
J. Phys. Chem. A, Vol. 104, No. 23, 2000 5521
The Pb + O2 Reaction. Properly linear ln [Pb]rel versus [O2]
plots could only be obtained for limited reaction conditions.
These were (i) from 660 to 920 K over narrow ranges of [M],
(0.95-1.3) × 1018 cm-3, and Vj 5-7 m s-1 and (ii) from 1010
to 1340 K also over a narrow range of [M], (6.2-8.8) × 1016
cm-3, and a somewhat wider range of Vj, 65-129 m s-1. Use
of a mullite reaction tube and Ar as bath gas led to within experi-
mental error to the same results; cf. Tables 4S and 5S in the
Supporting Information. These are indications that observations
are not predominantly for homogeneous processes, which is in
agreement with the results of Ryason and Smith11 mentioned
above.
The lower temperature rate coefficients have a negative
temperature dependence, Figure 4a. Linear regression yields
k4,l(660-920 K) ) 2.2 × 10-17 exp(2330 K/T) cm3 molecule-1
s-1. Residual analysis does not show any definite dependence
on the reaction condition parameters, although because of the
narrow ranges some dependence would probably not show. The
lack of an [M] dependence indicates that this is not a homog-
eneous addition reaction. Such reactions for a simple triatomic
system could not be at their high-pressure limit at these
temperatures. The abstraction reaction
Figure 3. Arrhenius plot of the Pb + HCl rate coefficients: (b)
measurements taken at 217.0 nm; (O) measurements taken at 283.3
nm; (s) best fit to the measurements (eq 12).
and covariance are σA ) 2.03 × 10-1 A2, σE ) 2.92 × 105,
and σAE ) 2.43 ×103 A. The (2σk precision limits are 11% at
1090 K and 10% at 1315 K, with corresponding confidence
limits of 25% and 24%, when allowing for systematic errors.
2
2
Temperature-dependent rate coefficient studies have been
made for HCl reactions with K,38 Na,39,40 Li,41 Al,34 Cr,31 and
Cu42 atoms. All have preexponentials in the about 10-10-10-9
cm3 molecule-1 s-1 range and are assumed to be abstraction
reactions. This path may also be assumed for reaction 3.
However, in the study of the Cu + HCl reaction, which showed
the rate coefficients to be pressure independent, it was shown
that an insertion product HCuCl also formed, from a second
minor channel beyond the reaction barrier. The pressure-
independence of the Pb and other polyvalent atom reactions
may thus not guarantee that the metal chloride is the only
product. Orbital symmetry calculations are helpful in deciding
whether insertion could occur.43 These suggest that HPbCl
formation from reaction 3 and Cl-Pb-Cl formation from
reaction 2 are possible.44 Further investigation would have to
establish if such processes occur.
Pb + O2 f PbO + O
(13)
would be 124 ( 7 kJ mol-1 endothermic12 and thus have rate
coefficients <1 × 10-16 cm3 molecule-1 s-1, too slow to be
measurable in this temperature range. Yet, a slow reaction with
rate coefficients (3-8) × 10-16 cm3 molecule-1 s-1 occurs,
suggesting a heterogeneous process. The aforementioned Husain
and Littler10 results show very different Arrhenius factors for
the three bath gases used, He, CO2, and C2H6. Though there is
considerable uncertainty in their data, the strong dependence
on the nature of M could indicate participation of a PbM + O2
type of three-body mechanism, rather than the more common
energy-transfer process. In that case the function of M at higher
temperatures apparently gets substituted by the walls. Ryason
and Smith interpreted their 870 K data as being in part due to
homogeneous reaction.11 Their 9.4 × 10-33 cm6 molecule-2 s-1
is about 2 orders of magnitude higher than k4,l/[M] at that
temperature. However, the wide scatter shown in their kobs/[O2]
vs [Ar] plot makes it doubtful that any meaningful data could
have been obtained from their measurements. Their11 and our
measurements may be taken as phenomenological for the
particular reactors used. It may be concluded that
The measured activation energy of reaction 3 of 143 ( 4 kJ
mol-1 puts an upper limit on its endothermicity of 136 ( 50 kJ
mol-1 at 1205 K,12 the midpoint of the temperature range over
which k was measured. From this and the enthalpy values from
the JANAF tables,12 an improved value of -4.4 ( 31 kJ mol-1
can be recovered for ∆fH298(PbCl,g). This leads to an increase
in D0(Pb-Cl) from12 299 ( 48 to 318 ( 31 kJ mol-1. The
enthalpy for reaction 2 accordingly is reassessed to be -79 (
31 kJ mol-1. A factor to be considered in the use of these new
figures is the presence of vibrationally excited HCl and its
possible effect on the apparent activation energy. Vibrational
enhancement of a reaction may become significant at high
temperatures, which can result in a sudden upward curvature
in Arrhenius plots.32 Assuming equilibrium, the first and the
second excited states of HCl (V ) 1, 2), with energies of 33.3
and 65.4 kJ mol-1 respectively,12 together represent 2.5% at
1090 K and 4.8% at 1315 K of the HCl population. Although
the concentration of vibrationally excited species thus almost
doubles over this temperature range, there is no indication of
curvature in the Arrhenius plot, suggesting no substantial
influence on the kinetics. If vibrational enhancement is signifi-
cant, but could not be detected due to the narrowness of the
temperature range, the actual Ea for HCl(V ) 0) would only be
smaller. In that case the figures given above would require
further corrections, the enthalpy of formation of PbCl being
smaller than the suggested -4.4 kJ mol-1 and the bond
Pb + O2 wall8 PbO2
(14)
is the likely dominant mechanism observed in the 660-920 K
range.
The higher temperature data show a positive temperature
dependence; cf. Figure 4b. Linear regression leads to k4,h(1010-
1340 K) ) 3.4 × 10-12 exp(-4823 K/T) cm3 molecule-1 s-1
.
Residual analysis does not show any definite dependence on
the reaction parameters, which might suggest the homogeneous
reaction 13. However, in addition to the discussed factors
arguing against this possibility, the above activation energy
corresponds to only 40 kJ mol-1, much less than the endother-
micity. This indicates a wall-catalyzed reaction. As the differ-
ence in temperature dependence from the lower temperature data
would suggest a change in mechanism, one may speculate that
the observed higher-temperature process is
Pb + O2 wall8 PbO + O
(15)
dissociation energy larger than 318 kJ mol-1
.

5522 J. Phys. Chem. A, Vol. 104, No. 23, 2000
Cosic and Fontijn
TABLE 3: Summary of Rate Coefficient Measurements of Pb + HCla
[M],
[HCl]max
,
reaction zone
length, cm
initial Pb
absorption, %
ki ( σki,
T, K
P, mbar
1017cm-3
1016 cm-3
Vj, m s-1
cm3 molecule-1 s-1
1194
1178
1183
1178
1088
1092
1092
1091
1203
1203
1203
1203
1158
1157
1156
1156
1228
1230
1314
1305
1136
1130
1124
1124
1304
1315
1315
1288
1283
1277
1276
1246
1236
1104
1099
1103
1092
1248
1257
1181
1183
1212
1212
1212
1212
1160
1160
1166
1172
1318
1318
1292
1292
1287
1304
1289
1303
1311
1227
1227
1238
1244
1263
1093
1093
1100
1100
1103
1119
1119
1127
1130
1130
44.3
44.3
34.7
132.0
107.7
58.0
136.6
93.3
2.68
2.72
2.12
8.11
7.17
3.85
9.06
6.19
4.59
6.04
8.55
5.45
5.69
8.67
6.96
4.16
2.66
2.71
3.04
3.40
9.13
4.78
7.88
6.33
5.82
4.68
7.56
4.95
4.97
5.09
7.41
7.67
4.94
8.42
6.31
9.52
9.82
8.04
7.99
7.43
8.60
8.50
8.44
3.73
8.76
7.56
8.89
7.70
6.00
6.12
6.20
7.59
7.66
7.69
7.57
7.75
3.99
3.96
6.29
6.29
7.99
7.98
4.19
9.17
9.17
7.35
7.35
7.26
7.13
5.30
5.26
7.77
8.85
2.76
2.56
2.00
7.64
6.96
3.73
8.79
6.01
4.27
5.61
7.94
5.06
5.29
8.06
6.47
3.86
3.53
3.60
4.04
4.52
8.69
4.55
7.50
6.03
3.78
3.05
3.51
3.22
3.23
3.31
3.44
3.56
2.29
8.25
6.18
9.33
9.61
7.64
7.59
7.06
8.17
4.48
4.45
3.54
8.32
7.17
8.43
7.30
5.69
5.80
5.88
4.31
4.35
5.22
7.14
5.65
3.66
3.64
5.11
5.11
7.60
7.58
3.99
9.56
9.56
7.67
7.67
6.49
6.37
4.73
4.70
6.95
7.91
19
17
22
6
6
12
5
7
10
8
6
9
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
10
20
20
10
20
20
20
10
20
20
20
20
20
20
20
20
20
20
20
20
30
19
46
33
30
42
31
36
51
50
43
46
39
30
32
35
8
(5.46 ( 0.39) × 10-16
(6.16 ( 0.69) × 10-16
(4.61 ( 0.54) × 10-16
(6.66 ( 0.39) × 10-16
(1.38 ( 0.10) × 10-16
(1.52 ( 0.11) × 10-16
(1.56 ( 0.12) × 10-16
(1.36 ( 0.08) × 10-16
(7.48 ( 1.04) × 10-16
(7.32 ( 0.62) × 10-16
(8.56 ( 0.72) × 10-16
(6.88 ( 0.67) × 10-16
(4.68 ( 0.33) × 10-16
(4.43 ( 0.37) × 10-16
(4.02 ( 0.35) × 10-16
(4.41 ( 0.39) × 10-16
(1.12 ( 0.12) × 10-15
(9.67 ( 0.67) × 10-16
(1.95 ( 0.17) × 10-15
(1.54 ( 0.13) × 10-15
(3.21 ( 0.20) × 10-16
(2.97 ( 0.20) × 10-16
(2.52 ( 0.18) × 10-16
(2.94 ( 0.29) × 10-16
(2.73 ( 0.17) × 10-15
(2.73 ( 0.16) × 10-15
(2.23 ( 0.15) × 10-15
(1.91 ( 0.12) × 10-15
(1.64 ( 0.10) × 10-15
(1.35 ( 0.10) × 10-15
(1.25 ( 0.08) × 10-15
(1.38 ( 0.08) × 10-15
(8.85 ( 0.85) × 10-16
(2.00 ( 0.22) × 10-16
(1.74 ( 0.18) × 10-16
(1.78 ( 0.19) × 10-16
(1.45 ( 0.11) × 10-16
(9.28 ( 0.76) × 10-16
(1.06 ( 0.08) × 10-15
(3.32 ( 0.31) × 10-16
(3.06 ( 0.23) × 10-16
(3.97 ( 0.24) × 10-16
(4.22 ( 0.27) × 10-16
(3.71 ( 0.24) × 10-16
(4.42 ( 0.25) × 10-16
(2.47 ( 0.17) × 10-16
(2.53 ( 0.17) × 10-16
(2.33 ( 0.13) × 10-16
(2.39 ( 0.15) × 10-16
(1.67 ( 0.11) × 10-15
(1.69 ( 0.10) × 10-15
(1.03 ( 0.06) × 10-15
(1.00 ( 0.06) × 10-15
(9.63 ( 0.62) × 10-16
(1.18 ( 0.10) × 10-15
(8.75 ( 0.54) × 10-16
(1.04 ( 0.08) × 10-15
(1.17 ( 0.09) × 10-15
(4.21 ( 0.31) × 10-16
(4.70 ( 0.27) × 10-16
(4.96 ( 0.40) × 10-16
(5.79 ( 0.47) × 10-16
(6.02 ( 0.49) × 10-16
(9.88 ( 0.72) × 10-17
(1.00 ( 0.07) × 10-16
(9.48 ( 0.65) × 10-17
(9.80 ( 1.03) × 10-17
(9.59 ( 0.71) × 10-17
(1.17 ( 0.07) × 10-16
(1.07 ( 0.14) × 10-16
(1.15 ( 0.08) × 10-16
(1.27 ( 0.11) × 10-16
(1.36 ( 0.09) × 10-16
76.3
100.3
142.0
90.5
91.0
8
5
7
138.6
111.2
66.4
45.1
46.0
55.2
61.3
141.3
74.0
122.4
98.3
104.8
85.0
137.3
88.0
88.0
89.7
130.6
132.0
84.4
128.4
95.8
145.0
145.3
138.6
138.6
121.2
140.5
142.2
141.3
62.4
146.6
121.0
142.4
124.0
97.0
111.3
112.9
135.4
136.6
136.6
136.2
138.0
71.7
11
15
15
13
12
5
10
6
7
8
10
6
9
9
9
6
6
9
6
7
5
5
6
6
6
5
5
5
12
5
6
5
6
8
8
7
7
7
7
6
8
12
12
9
9
7
7
11
5
5
7
7
7
7
9
9
6
8
28
25
49
48
44
45
41
50
47
48
42
39
31
15
16
38
41
37
28
39
40
23
20
19
19
28
20
25
23
27
31
43
44
21
20
23
27
16
46
48
51
53
47
44
49
38
39
44
45
47
46
52
53
49
48
71.7
106.6
106.6
136.6
137.0
73.0
138.4
138.4
111.7
111.7
110.6
110.2
81.8
81.8
121.3
138.1
6

Pb Reactions with N2O, Cl2, HCl, and O2
J. Phys. Chem. A, Vol. 104, No. 23, 2000 5523
TABLE 3 (Continued)
[M],
[HCl]max
,
reaction zone
length, cm
initial Pb
absorption, %
ki ( σki,
T, K
P, mbar
1017cm-3
1016 cm-3
Vj, m s-1
cm3 molecule-1 s-1
1154
1154
1162
1164
1159
1177
1181
1180
1204
1211
1212
1232
1224
1299
1292
1300
1260
1188
1153
1170
1166
1201
1095
1109
1121
1133
1129
1125
1285
1288
1283
1283
1289
1290
1291
1299
1300
1300
1095
1098
1093
1094
1094
138.2
81.3
81.0
132.1
132.9
133.3
134.0
107.3
107.2
82.9
8.67
5.10
5.05
8.22
8.30
8.20
8.21
6.59
6.45
4.96
4.97
4.87
8.03
5.90
6.46
6.45
5.82
6.18
6.41
3.72
7.53
7.31
8.11
7.83
7.50
7.16
7.42
9.30
4.69
7.17
7.32
8.01
7.95
5.72
5.78
5.71
5.17
6.34
6.20
6.35
9.31
9.21
9.21
7.75
4.56
4.51
6.69
6.76
6.68
6.69
5.36
5.25
4.04
4.05
3.97
6.54
4.81
5.73
5.71
4.39
4.66
4.84
3.01
6.10
5.92
6.56
6.34
6.07
5.79
6.00
7.53
4.21
2.94
6.05
6.63
3.23
6.52
6.60
3.18
2.89
3.54
7.06
7.07
9.62
9.71
9.71
6
10
10
7
7
7
7
8
8
11
11
11
7
9
9
9
10
9
9
15
7
7
7
7
7
8
7
6
10
5
5
5
5
7
7
7
7
6
20
20
20
20
10
10
20
20
20
20
20
20
10
20
10
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
10
10
20
10
10
20
20
20
20
20
10
10
10
33
43
44
31
32
39
38
41
50
45
45
38
32
49
45
40
51
31
34
51
42
37
38
44
47
52
48
32
(1.78 ( 0.11) × 10-16
(1.48 ( 0.18) × 10-16
(1.89 ( 0.11) × 10-16
(1.91 ( 0.11) × 10-16
(1.90 ( 0.24) × 10-16
(2.30 ( 0.24) × 10-16
(2.48 ( 0.23) × 10-16
(2.00 ( 0.17) × 10-16
(2.81 ( 0.23) × 10-16
(3.05 ( 0.26) × 10-16
(2.96 ( 0.28) × 10-16
(3.81 ( 0.48) × 10-16
(3.74 ( 0.28) × 10-16
(1.00 ( 0.06) × 10-15
(7.47 ( 0.57) × 10-16
(8.56 ( 0.63) × 10-16
(1.27 ( 0.07) × 10-15
(3.91 ( 0.42) × 10-16
(2.43 ( 0.17) × 10-16
(3.27 ( 0.59) × 10-16
(3.04 ( 0.27) × 10-16
(3.95 ( 0.32) × 10-16
(8.69 ( 0.75) × 10-17
(1.09 ( 0.12) × 10-16
(1.61 ( 0.10) × 10-16
(2.02 ( 0.12) × 10-16
(1.52 ( 0.10) × 10-16
(2.05 ( 0.21) × 10-16
(1.90 ( 0.27) × 10-15
(1.70 ( 0.09) × 10-15
(1.30 ( 0.08) × 10-15
(1.10 ( 0.07) × 10-15
(1.60 ( 0.09) × 10-15
(1.00 ( 0.07) × 10-15
(1.10 ( 0.07) × 10-15
(1.60 ( 0.09) × 10-15
(1.90 ( 0.12) × 10-15
(1.30 ( 0.08) × 10-15
(1.60 ( 0.12) × 10-16
(1.50 ( 0.10) × 10-16
(1.20 ( 0.09) × 10-16
(1.10 ( 0.07) × 10-16
(1.10 ( 0.07) × 10-16
83.2
82.9
135.7
105.9
115.3
115.7
101.3
101.3
102.1
60.1
121.3
121.3
122.6
120.0
116.1
112.0
115.7
144.5
62.37
95.58
97.23
106.33
106.10
76.36
77.22
76.78
69.60
85.32
70.28
72.11
105.29
104.28
104.28
46b
63b
61b
61b
58b
70b
61b
61b
61b
61b
42b
40b
40b
41b
41b
6
6
5
5
5
a The measurements are reported in the sequence in which they were obtained. b The 217.0 nm absorption line was used in these experiments.
In all other experiments the 283.3 nm line was used.
The activation energy for the equivalent homogeneous
reaction 13 is likely to be higher than the 124 ( 7 kJ mol-1
figure, based on observations of the reverse process. Golomb
and Best released tetraethyllead at 100-150 km altitude from
a sounding rocket. The resulting sunlight-induced PbO fluo-
rescence persisted for a considerable time, indicating PbO
reaction with O atoms to be slow.45 Oldenborg et al.46 argued
from this, and consideration of the reaction path, that a barrier
is present. They concluded that the ground-state process
that respect the Pb + O2 system thus may be similar. However,
there was no evidence for a heterogeneous component in those
reactions. The rate coefficients obtained there were several
orders of magnitude higher than that obtained for Pb + O2 at
comparable temperatures, which would dwarf any similarly slow
heterogeneous reaction. The Cr reaction was studied in an,
essentially wall-less, HTP (high-temperature photochemistry)
reactor47 where no wall reaction could affect the measurements.
The “nearest neighbor” to Pb/O2 is the very fast, exothermic
Sn + O2 abstraction reaction. Its k(380-1840 K) ) 5.1 × 10-13
-
PbO(X1Σ) + O(3P) f Pb(3P) + O2(X3Σ-g )
(16)
(T/K)0.79 exp(-437 K/T) cm3 molecule-1 s-1 49
which would
,
also dominate any much slower heterogeneous reactions.
should proceed on a triplet surface, with the PbO2 triplet
intermediate lying above its singlet ground state.
Conclusions
Two other metal oxidation reactions, studied in the temper-
ature range of the present work, have shown a change from a
(third order) association reaction at low temperatures to a
predominantly (second order) abstraction reaction at high
temperatures. These are Cr + O2, for which abstraction is 40
( 42 kJ mol-1 endothermic, studied47 from 290 to 1510 K and
AlO + O2, for which abstraction is 96 ( 40 kJ mol-1
endothermic, and which was studied48 from 305 to 1690 K. In
The Pb(63P0) reactions with N2O, Cl2, and HCl have been
studied. In the temperature domains investigated no curvature
is evident in their Arrhenius plots. Three parameter fits k(T) )
ATn exp(-E /RT) have also been made but did not further im-
prove the precision limits of the results. Many other metal oxi-
dation reactions studied in this laboratory show the predicted50
Arrhenius plot curvature, but these were usually studied over
wider temperature ranges than was possible for the Pb reactions.

5524 J. Phys. Chem. A, Vol. 104, No. 23, 2000
Cosic and Fontijn
(10) Husain, D.; Littler, J. G. F. Combust. Flame, 1974, 22, 295. These
authors do not give the temperature range for the O2 reaction. Presumably
it was the same as for the NO data shown.
(11) Ryason, P. R.; Smith, E. A. J. Phys. Chem. 1971, 75, 2259.
(12) Unless otherwise indicated the ∆H298 values were based on: Chase,
M. W., Jr. NIST-JANAF Thermochemical Tables; J. Phys. Chem. Ref. Data
1998, Monograph 9.
(13) Belyung, D. P.; Futerko, P. M.; Fontijn, A. J. Chem. Phys. 1995,
102, 155.
(14) Blue, A. S.; Belyung, D. P.; Fontijn, A. J. Chem. Phys. 1997, 107,
3791.
(15) Fontijn, A. Pure Appl. Chem. 1998, 70, 469.
(16) Fontijn, A.; Futerko, P. M. In Gas-Phase Metal Reactions; Fontijn,
A., Ed.; North-Holland: Amsterdam, 1992; Chapter 6.
(17) Slavejkov, A. G.; Futerko, P. M.; Fontijn, A. 23rd Symp. (Int.)
Combust.; The Combustion Institute: Pittsburgh, PA, 1990; p 155.
(18) Fontijn, A.; Felder, W. In ReactiVe Intermediates in the Gas-
Phase: Generation and Monitoring; Setser, D. W., Ed.; Academic Press:
New York. 1979; Chapter 2.
(19) Slavejkov, A.; Stanton, C. T.; Fontijn, A. J. Phys. Chem. 1990,
94, 3347.
(20) Irvin, J. A.; Quickenden, I. T. J. Chem. Educ. 1983, 60, 711.
(21) Felder, W.; Fontijn, A. J. Chem. Phys. 1978, 69, 1112, and
references discussed therein.
(22) Futerko, P. M.; Slavejkov, A. G.; Fontijn, A. J. Phys. Chem. 1993,
97, 11950.
(23) STANJAN (Reynolds, W. C. The Element Potential Method for
Chemical Equilibrium Analysis; Implementation in the InteractiVe Program
STANJAN; Department of Mechanical Engineering, Stanford University,
January 1986) calculation indicated that the use of N2 allowed heating to
roughly 200 K higher than with Ar for the same equilibrium dissociation.
(24) It has been previously shown19,21,34 that at typical reaction times
used in HTFFRs oxidants such as N2O, Cl2, and HCl can be used at
temperatures several hundred kelvin higher than equilibrium dissociation
would indicate. This can be attributed to kinetic constraints on the
dissociation process.
(25) Press, W. H.; Flannery, B. P.; Teukolsky, S. A.; Vetterling, W. T.
Numerical Recipes; Cambridge University: Cambridge, 1986; Chapter 14.
(26) Wentworth, W. E. J. Chem. Educ. 1965, 42, 96, 162.
(27) Ferguson, E. E.; Fehsenfeld, F. C.; Schmeltekopf, A. L. AdV. At.
Mol. Phys. 1969, 5, 1.
Figure 4. Arrhenius plots of the Pb + O2 rate coefficients: (O)
measurements taken using N2 and quartz reaction tube; (b) measure-
ments taken using Ar and quartz reaction tube; (]) measurements taken
using N2 and mullite reaction tube; (s) best fits to the measurements
at (a) 660-920 and (b) 1010-1340 K.
The Pb/O2 system appears dominated by heterogeneous
processes, and the apparent rate coefficient values obtained
should be considered as phenomenological for the reactor used.
In the combustion of solids such processes would dominate for
the combination of these reactants. Further studies of homoge-
neous reactions of this system would require the use of reactors
that operate essentially wall free. Such an environment can be
provided for example at lower temperatures by the equipment
in Husain’s laboratory,7-10 from 300 to 1800 K in an HTP
reactor,15,16,47 or in a shock tube.
(28) Fontijn, A.; Felder, W. J. Phys. Chem. 1979, 83, 24.
(29) Fontijn, A.; Felder, W. J. Chem. Phys. 1980, 72, 4315, and
references discussed therein.
(30) Pearse, R. W. B.; Gaydon, A. G. The Identification of Molecular
Spectra, 4th ed.; John Wiley & Sons: New York, 1976.
(31) Fontijn, A.; Blue, A. S.; Narayan, A. S.; Bajaj, P. J. Combust. Sci.
Technol. 1994, 101, 59.
(32) Narayan, A. S.; Futerko, P. M.; Fontijn, A. J. Phys. Chem. 1992,
96, 290.
(33) This is the Reynolds number for flow to fully develop in a tube,
where a is tube radius and ν bath gas viscosity; see: Potter, M. C.; Foss,
J. F. Fluid Mechanics; Great Lake Press: Okemos, MI, 1982; p 274.
(34) Rogowski, D. F.; Marshall, P.; Fontijn, A. J. Phys. Chem. 1989,
93, 1118.
(35) Vinckier, C.; Christaensen, P. J. Phys. Chem. 1992, 96, 8423.
(36) Campbell, M. L. J. Phys. Chem. 1993, 97, 3922.
(37) Vinckier, C.; Verhaele, T.; Vanhees, I. J. Chem. Soc., Faraday
Trans. 1996, 92, 1455.
Supporting Information Available: Tables 4S and 5S. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(38) Helmer, M.; Plane, J. M. C. J. Chem. Phys. 1993, 99, 7696.
(39) Plane, J. M. C.; Rajasekhar, B.; Bartolotti, L. J. Chem. Phys. 1989,
91, 6177.
(40) Husain, D.; Marshall, P. Int. J. Chem. Kinet. 1986, 18, 83.
(41) Plane, J. M. C.; Saltzman, E. S. J. Chem. Phys. 1987, 87, 4606.
(42) Belyung, D. P.; Hranisavljevic, J.; Kashireninov, O. E.; Santana,
G. M.; Fontijn, A.; Marshall, P. J. Phys. Chem. 1996, 100, 17835.
(43) Hranisavljevic, J.; Fontijn, A. J. Phys. Chem. 1997, 101, 2323.
(44) Hranisavljevic, J. Ph.D. Thesis, Rensselaer Polytechnic Institute,
1997; p 123.
Acknowledgment. This work was supported under NSF
Grants CTS-9905265 and CTS-9632492, Dr. Farley Fisher,
Program Director. We also thank William Flaherty, Charles
Fung, and Christine Brown for dedicated assistance.
References and Notes
(1) Linak, W. P.; Srivastava, R. K.; Wendt, J. O. L. Combust. Flame
1995, 100, 241.
(2) Buckley, S. G.; Sawyer, R. F.; Koshland, C. P.; Lucas, D. First
United States Section Meeting of the Combustion Institute; The Combustion
Institute: Pittsburgh, PA, 1999; p 877.
(45) Golomb, D.; Best, G. T. Trans. AGU 1974, 55, 366.
(46) Oldenborg, R. C.; Dickson, C. R.; Zare, R. N. J. Mol. Spectrosc.
1975, 58, 283.
(3) Saxena, S. C.; Jotshi, C. Prog. Energy Combust. Sci. 1996, 22,
(47) Narayan, A. S.; Slavejkov, A. G.; Fontijn, A. 24th Symp. (Int.)
Combust.; The Combustion Institute: Pittsburgh, PA, 1992; p 727.
(48) Belyung, D. P.; Fontijn, A. J. Phys. Chem. 1995, 99, 12225.
(49) Fontijn, A.; Bajaj, P. N. J. Phys. Chem. 1996, 100, 7085.
(50) Fontijn, A.; Zellner, R. In Reaction of Small Transient Species.
Kinetics and Energetics; Fontijn, A., Clyne, M. A. A., Eds.; Academic
Press: London, 1983; Chapter 1.
401.
(4) Bell, C. F.; Husain, D. J. Photochem. 1985, 29, 267.
(5) Husain, D.; Littler, J. G. F. J. Photochem. 1973/74, 2, 247.
(6) Cross, P. J.; Husain, D. J. Photochem. 1977, 7, 157.
(7) Husain, D.; Sealy, I. P. J. Photochem. 1986, 34, 245.
(8) Husain, D.; Sealy, I. P. J. Photochem. 1985, 30, 387.
(9) Husain, D.; Sealy, I. P. J. Photochem. 1986, 35, 259.