Abstract
Abstract.
Rate coefficients (k5) for the title reaction were ob-
tained using pulsed laser photolytic generation of OH cou-
pled to its detection by laser-induced fluorescence (PLP–
LIF). More than 80 determinations of k5
were carried out in nitrogen or air bath gas at various temperatures and pres-
sures. The accuracy of the rate coefficients obtained was en-
hanced by in situ measurement of the concentrations of both
HNO3 reactant and NO2 impurity. The rate coefficients show
both temperature and pressure dependence with a rapid in-
crease in k5 at low temperatures. The pressure dependence
was weak at room temperature but increased significantly at
low temperatures. The entire data set was combined with se-
lected literature values of k5 and parameterised using a com-
bination of pressure-dependent and -independent terms to
give an expression that covers the relevant pressure and tem-
perature range for the atmosphere. A global model, using the
new parameterisation for
k
5
rather than those presently ac-
cepted, indicated small but significant latitude- and altitude-
dependent changes in the HNO
3
/
NO
x
ratio of between
−
6 and
+
6 %. Effective HNO
3
absorption cross sections
(184.95 and 213.86 nm, units of cm
2
molecule
−
1
) were ob-
tained as part of this work:
σ
213
.
86
=
4.52
+
0
.
23
−
0
.
12
×
10
−
19
and
σ
184
.
95
=
1.61
+
0
.
08
−
0
.
04
×
10
−
17
.
Rate coefficients (k5) for the title reaction were ob-
tained using pulsed laser photolytic generation of OH cou-
pled to its detection by laser-induced fluorescence (PLP–
LIF). More than 80 determinations of k5
were carried out in nitrogen or air bath gas at various temperatures and pres-
sures. The accuracy of the rate coefficients obtained was en-
hanced by in situ measurement of the concentrations of both
HNO3 reactant and NO2 impurity. The rate coefficients show
both temperature and pressure dependence with a rapid in-
crease in k5 at low temperatures. The pressure dependence
was weak at room temperature but increased significantly at
low temperatures. The entire data set was combined with se-
lected literature values of k5 and parameterised using a com-
bination of pressure-dependent and -independent terms to
give an expression that covers the relevant pressure and tem-
perature range for the atmosphere. A global model, using the
new parameterisation for
k
5
rather than those presently ac-
cepted, indicated small but significant latitude- and altitude-
dependent changes in the HNO
3
/
NO
x
ratio of between
−
6 and
+
6 %. Effective HNO
3
absorption cross sections
(184.95 and 213.86 nm, units of cm
2
molecule
−
1
) were ob-
tained as part of this work:
σ
213
.
86
=
4.52
+
0
.
23
−
0
.
12
×
10
−
19
and
σ
184
.
95
=
1.61
+
0
.
08
−
0
.
04
×
10
−
17
.
| Original language | English |
|---|---|
| Pages (from-to) | 2381-2394 |
| Number of pages | 14 |
| Journal | Atmospheric Chemistry and Physics |
| Volume | 18 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - 19 Feb 2018 |
