Photodissociation dynamics of state-selected resonances of HCO X̃ 2A′ prepared by stimulated emission pumping

Abstract

Articles you may be interested inState-selected imaging studies of formic acid photodissociation dynamics J. Chem. Phys. 132, 154306 (2010); 10.1063/1.3386576 CO product distribution from metastable levels of HCO X2 A' prepared by stimulated emission pumping J. Chem. Phys. 98, 5095 (1993); 10.1063/1.464966 Stateselected photodissociation dynamics of HONO(A1 A'): Characterization of the NO fragmentMetastable resonances on the ground electronic state of the HCO radical have been prepared by stimulated emission pumping. The resonances have energies 5000 to 10 000 cm Ϫ1 above the dissociation limit of HCO and can be assigned by their vibrational and asymmetric-top rotational character. The transition linewidths of the resonances and the rotational and vibrational distributions of the CO dissociation products have been measured. The linewidths show a strong dependence on the vibrational character of the resonance rather than a monotonic dependence on energy, and thus provide an important example of nonstatistical behavior. CO͑vϭ2͒ was produced in the decay of all six resonances studied, while only the three highest energy resonances produced measurable amounts of CO͑vϭ3͒. CO rotational distributions with population in low-J states, which often showed nonstatistical structure, were characteristic of the products from all the resonances studied. The rotational distributions depend both on the vibrational character of the parent state and on the rotational state prepared in the HCO. The experimental results are compared and contrasted with previous quantum mechanical calculations and analyzed in the context of a modified Franck-Condon model for the dissociation.

Unimolecular dissociation dynamics of highly vibrationally excited DCO(X̃ 2A). II. Calculation of resonance energies and widths and comparison with high-resolution spectroscopic data

“…Since all experimental energies, covering about 20 000 cm Ϫ1 , were included in the final adjustment the deviations from the experimental energies are more or less uniform over the entire energy range; the rms deviation is only 17 cm Ϫ1 . However, not only the energies of the resonances but also their widths, with only very few exceptions, as well as the few measured 20,21 final rotational state distributions of the CO fragment are well reproduced by the dynamics calculations using the new PES. Hereafter, we shall refer to this new PES as the WKS ͑Werner-KellerSchinke͒ PES.…”

Ab initio characterization of the low-lying vibrations of HCO (DCO) in the B̃ 2A′ state

“…Recently, there has been a spurt of new experiments probing the B 2 AЈ -X 2 AЈ transition, focusing on the characterization of quasibound vibrational states in the X 2 AЈ-state. [1][2][3][4] These experiments complement theoretical studies of these quasibound states which have been reported for a number of years, 4 -9 and which also have served as benchmark calculations for testing new methods to calculate quasibound states. 10,11 Somewhat ancillary to these studies, but quite interesting and important in its own right is the characterization of the vibrations of HCO ͑and DCO͒ in the B -state.…”

Elementary reactions of formyl (HCO) radical studied by laser photolysis—transient absorption spectroscopy

“…All four profiles obtained were simultaneously fitted by a numerical solution of a system of differential equations corresponding to the reaction mechanism. The reaction mechanism used in the fits includes reactions (1-3) and additional reactions (7)(8)(9)(10)(11):…”

“…Due to relatively weak C-H bond and large vibrational frequencies, the radical has isolated resonances at energies above the dissociation threshold. These resonances have been extensively studied both using spectroscopic techniques and theoretically [4][5][6][7][8][9]. This feature is expected to have a significant impact on the pressure fall-off curve for reaction (1) [10].…”