Nascent vibrational energy distributions of O2(X3Sigma(g)-, nu = 6-13) generated in the photolysis of O3 at 266 nm.

The vibrational levels of O2(X3Sigma(g)-) generated in the ultraviolet photolysis of O3 at 266 nm were detected via laser-induced fluorescence (LIF) of the B3Sigma(u)- - X3Sigma(g)- system. The nascent vibrational energy distributions of O2(X3Sigma(g)-, nu = 6-13) have been measured by two different methods. One is a kinetic analysis based on the originally developed integrated profiles method (IPM). The time-resolved LIF of a single vibrational level has been recorded in the presence of CF4 or O2 as a relaxation partner. The IPM analysis of the profiles gave the relative detectabilities of adjacent vibrational levels, and the initial relative populations of the vibrational levels have been determined from the intensities of LIF subsequent to the photolysis. The other is the analysis of the area intensities of the LIF of the vibrational levels of interest. The rotational levels with the identical quantum numbers of different vibrational levels in the X3Sigma(g)- state were excited to a common vibrational level nu' = 0 in the B3Sigma(u)- state. Correction for the LIF intensities with the Franck-Condon factors was made, and the initial relative populations have been obtained. The two different methods have given similar nascent vibrational energy distributions, and comparison to the previous reports has been made.

Vibrational relaxation of O2(X3 Sigma g-, v = 9-13) by collisions with O2.

Vibrationally excited O(2)(X(3) Sigmag(-)) was generated in the UV laser flash photolysis of O(3) and single vibrational level was detected via laser-induced fluorescence (LIF) in the B(3) Sigmau(-)-X(3) Sigmag(-) system. The time-resolved LIF of adjacent vibrational levels has been analyzed by the integrated-profiles method and the rate coefficients for single-quantum relaxation, O(2)(X(3)Sigmag(-), v = 9-13)+ O(2)(v = 0)--> O(2)(X(3)Sigmag(-), v - 1)+ O(2)(v = 1), have been determined. To the best of our knowledge, the rate coefficients for v = 12 and 13 are measured for the first time in the present study. The efficiency of relaxation is higher at lower vibrational levels, indicating that a small energy mismatch is suitable for the energy transfer. The vibrational level dependence of all the rate coefficients for the relaxation measured in the present study and previously reported by several groups can be rationalized by the energy gap law.