D. Bauer et al., ULTRAVIOLET-VISIBLE ABSORPTION CROSS-SECTIONS OF GASEOUS HOI AND ITS PHOTOLYSIS AT 355 NM, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 102(17), 1998, pp. 2857-2864
The absorption cross sections of HOI have been obtained at room temper
ature between 280 and 490 nm. HOI was generated in situ by laser photo
lytic production of OH in the presence of I-2 and its absorption of UV
-visible light measured using both a gated diode array camera and at s
everal wavelengths by a photomultiplier. Calibration was performed rel
ative to I-2 loss. The absorption spectrum consists of two unstructure
d bands with maxima at 340.4 nm (sigma(max) = (3.85 +/- 0.4) x 10(-19)
cm(2)) and 406.3 nm (sigma(max) = (3.30 +/- 0.3) x 10(-19) cm(2)) and
is approximated closely by a semilogarithmic two-band Gaussian functi
on. The cross section data were used to calculate an HOI lifetime with
respect to photodissociation in the troposphere of between 170 and 10
0 s for solar zenith angles of 70 degrees and 30 degrees, respectively
. The photolysis of HOI was investigated at 355 nm and was found to ge
nerate OH radicals with a quantum yield close to unity.