Jb. Burkholder et al., UV VISIBLE AND IR ABSORPTION CROSS-SECTIONS OF BRONO2, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 100(D8), 1995, pp. 16793-16800
The absorption cross sections of BrONO2 between 200 and 500 nm were me
asured over the temperature range 298 to 220 K using a diode array spe
ctrometer. The BrONO2 absorption cross sections are weakly dependent o
n temperature at wavelengths < 450 nm (less than 10% change between 29
8 and 220 K) but decrease rapidly with decreasing temperature at wavel
engths > 450 nm; at 480 nm the cross section decreased by similar to 3
5% in going from 298 K to 220 K. Our room temperature absorption cross
sections are in good agreement with the measurements of Spencer and R
owland (1978) over the common wavelength range of the measurements, 20
0 to 390 nm. We show that wavelengths longer than 390 nm must be inclu
ded in the calculation of the BrONO2 atmospheric photolysis rate. We a
lso show that photolysis of BrONO2 could be a significant atmospheric
loss process for odd oxygen (due to halogen chemistry) below about 25
km, The infrared absorption cross sections for the BrONO2 band centere
d at 803.3 cm(-1) were also measured. The integrated band strength was
(2.7 +/- 0.5) x 10(-17) cm(2) molecule(-1) cm(-1).