Absolute integrated cross sections for some O2 Herzberg I transitions near 248–249 nm

Abstract

A frequency doubled tunable dye laser system with ϳ0.4 cm Ϫ1 resolution was used to measure the integrated absorption cross sections of more than 20 rotational transitions in the O 2 Herzberg I (A 3 ⌺ u ϩ ←X 3 ⌺ g Ϫ) 8-0 and 9-0 vibrational bands near 248 nm and 249 nm. Oxygen pressures from 200 to 800 Torr and path lengths from 5 to 25 m were employed. The measured absorbances were fitted using a nonlinear least squares analysis and Beer's Law to obtain absolute values for the individual transition integrated cross sections in good agreement with a recent spectral simulation and experimental data. By using the spectral simulation in conjunction with the present experimental results, total oscillator strengths in reasonable agreement with literature values were estimated for the 8-0 and 9-0 vibrational bands.

Photochemical Kinetics of Vibrationally Excited Ozone Produced in the 248 nm Photolysis of O2/O3 Mixtures

“…In the present system, ozone is the only significant absorber; absorption by O 2 at 248 nm is very small and can be neglected. − The photolysis of O 3 is well known to proceed by the two pathways in reaction 1 and the branching ratio is k 1a / k 1 = 0.91 ± 0.03 at 248 nm . The O( 1 D) produced in the photodissociation reacts very quickly with the abundant O 2 .…”