Details

Autor(en) / Beteiligte

• Vansco, Michael F
• Li, Hongwei
• Lester, Marsha I

Titel

Prompt release of O 1 D products upon UV excitation of CH 2 OO Criegee intermediates

Ist Teil von

• The Journal of chemical physics, 2017-07, Vol.147 (1), p.013907

Ort / Verlag

United States

Erscheinungsjahr

2017

Link zum Volltext

Quelle

AIP Journals

Beschreibungen/Notizen

• Velocity map imaging has been used to characterize the angular and velocity distributions of O D photofragments arising from UV excitation of the simplest Criegee intermediate CH OO in the long wavelength tail region (364 to 417 nm) of the B A'-X A' spectrum. The O D images exhibit anisotropic angular distributions indicative of rapid dissociation to H CO X A + O D products, which occurs faster than the rotational period (ps) of CH OO. As a result, the broad oscillatory structure reported previously in the long wavelength region of the UV absorption spectrum is attributed to short-lived resonances associated with the excited B A' state of CH OO, which decay by nonadiabatic coupling to repulsive singlet states. The total kinetic energy distributions show that nearly half of the available energy, on average, is partitioned to product translation. The balance results in significant internal excitation of the H CO co-fragments. The product anisotropy and energy partitioning are unchanged across the UV spectrum and consistent with previously reported experimental and theoretical findings of the CH OO B-X transition moment and dissociation energy to H CO X A + O D products.