DETERMINATION OF THE ABSORBENCY CROSS-SECTIONS FOR N2O5 BAND SYSTEMS IN THE REGION 250-650 CM(-1)

Measurements of N2O5 together with measurements of pure samples of the main decomposition products HNO3 and N2O in the spectral region 250-6 50 cm(-1) have been carried out in the temperature range from room tem perature down to -60 degrees C at nine different temperatures and at r esolutions (FWHM) of 0.067 and 0.0067 cm(-1). For the two lowest tempe ratures, -50 and -60 degrees C, the absorbance cross sections of the 3 50 cm(-1) band of N2O5 could be determined and are equal to within the accuracy of the determination. The peak absorbance cross section aver aged for these two lowest temperatures at 352.50 cm(-1) is sigma(peak) = (5.17 +/- 0.45) x 10(-19) cm(2) molecule(-1). A marked temperature dependence of the band shape, and reproducible fine structure at the l ower temperatures, could be distinguished. The procedure yielded analo gous data for the 570 cm(-1) band, though with lower absolute accuracy . The peak absorbance cross section at 581.60 cm(-1) is sigma(peak) = (7.70 +/- 0.67) X 10(-19) cm(2) molecule(-1), averaged for -50 and -60 degrees C. (C) 1996 Academic Press, Inc.