The vibrational distribution of O2(X 3Σg−) produced in the photodissociation of ozone between 226 and 240 and at 266 nm

Abstract

Photolysis wavelength dependence of the translational anisotropy and the angular momentum polarization of O 2 ( a Δ g 1 ) formed from the UV photodissociation of O 3The energy distribution, angular distribution, and alignment of the O ( 1 D 2 ) fragment from the photodissociation of ozone between 235 and 305 nm Resonance-enhanced multiphoton ionization coupled with time-of-flight product imaging has been used to study the O 3 (X 1 A 1 )ϩh→O(2p 3 P J )ϩO 2 (X 3 ⌺ g Ϫ ) product channel in the UV ͑ultraviolet͒ photodissociation of ozone at photolysis wavelengths of 226, 230, 233, 234, 240, and 266 nm. These imaging experiments, together with a measurement of the branching ratio into the different spin orbit states of the O atom, allowed the determination of the yields of the O 2 product in vibrational states greater than or equal to 26 as a function of wavelength. It was found that at 226, 230, 233, 234, and 240 nm, the yield was 11.8Ϯ1.9%, 11.5Ϯ1.2%, 8.2Ϯ2.0%, 4.7Ϯ1.8%, and 0.6Ϯ0.1%, respectively.

Are Vibrationally Excited Molecules a Clue for the “O3 Deficit Problem” and “HOx Dilemma” in the Middle Atmosphere?

“…After reaching the maximum, the predicted efficiency for O 3 production is considerably reduced, 3 with the model failing to ameliorate the ozone deficit problem. In fact, a more recent analysis has shown 83 that such a model cannot account for the deficit at higher altitudes even if all O 2 (V) leads to production of ozone via a reaction similar to (25).…”

Steady-State Distributions of O2 and OH in the High Atmosphere and Implications in the Ozone Chemistry

“…At wavelengths of 226, 230, 233, 234, and 240 nm, virtually all oxygen molecules formed from the O 3 photodissociation are vibrationally excited. 7 Typically, the O 2 (V) formed at 226 nm shows a bimodal vibrational distribution peaking in the vicinity of V ) 15 and V ) 27, 4 while at longer wavelengths the peak at V ) 27 disappears, 7 although there is still an appreciable fraction of highly vibrationally excited O 2 . Note that in the past it was the reaction that was considered to be primarily responsible for O 2 (V) formation after photolysis of O 3 (rather than from direct photolysis 8 ).…”

Dynamics Study of the OH + O2Branching Atmospheric Reaction. 4. Influence of Vibrational Relaxation in Collisions Involving Highly Excited Species

“…The existence of vibrationally hot species [1][2][3][4][5][6][7][8][9][10] under conditions of nonlocal thermodynamic equilibrium (or simply local thermodynamic disequilibrium, 10 LTD) in the stratosphere allows the occurrence of endoergic reactions which would not be viable otherwise. Despite this, atmospheric models continue, to our knowledge, to consider only reactions under equilibration conditions.…”