Table of Contents
Laser Chemistry
Volume 10, Issue 4, Pages 207-226
http://dx.doi.org/10.1155/1990/93626

Pulsed Co2-Laser Excitation of 03/02 Mixtures at Pressures From 0.16 to 1.20 Bar

1Physikalisch-Chemisches Institut, Ruprecht-Karls-Universität, Im Neuenheimer Feld 253, Heidelberg D-6900, Germany
2Bayer AG, Abt. FS-IT, Dormagen D-4047, Germany

Received 21 November 1989

Copyright © 1990 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An investigation is presented of the transient vibrational excitation of O3 in the collision dominated regime initiated by pulsed CO2-laser radiation. IR-UV-double resonance experiments and measurements of the absorbance for the CO2-laser lines 9P18, 20, and 22 were carried out. Mixtures of O3 (p=17 mbar) with 02 were investigated at pressures of 160 mbar Pmixt1200 mbar and laser fluences of 0.10J/cm2Fin<2J/cm2 . The results are interpreted by numerical simulations in terms of a comprehensive excitation/relaxation model based upon SSH-theory. Concerning the evolution of the excitation, simulated transients of the UV-absorbance compare well with the corresponding observed signals. The saturation of the absorbing O3-transitions is demonstrated by the measured fluence dependence of the absorption coefficient at the laser wavelengths. The extent of the 03-excitation can be deduced according to the model from the maximum vibrational temperature Tm reached in the v1- and v3-oscillators. Tm accessible via the UV-transients and also via the absorbed laser energy in the case of slow relaxation at 160 160mbarPmixt340 mbar. In this range both techniques result in the same values for Tm. The experimental and the corresponding simulated Tm depend exponentially on the laser fluence (Tm=const.F¯in0.3) provided Tm>400K being also confirmed up to Pmixt=1200 mbar by the observed UV-transients.