Fully state-resolved photodissociation of formaldehyde, H{sub 2}CO{yields}H+HCO: K conservation and a rigorous test of statistical theories
- School of Chemistry, University of Sydney, New South Wales 2006 (Australia)
The photodissociation dynamics of the reaction H{sub 2}CO+h{nu}{yields}H+HCO have been investigated in the range 60-400 cm{sup -1} above the reaction threshold. Supersonically cooled formaldehyde was excited into 15 specific J, K{sub a}, K{sub c} rotational states in two vibrational levels 2{sup 1} 4{sup 1} 6{sup 1} and 2{sup 2} 4{sup 1} in the A-tilde({sup 1}A{sub 2}) state. The laser-induced fluorescence spectra of the nascent HCO fragment provided detailed product state distributions (PSDs), resolved by N, K{sub a}, K{sub c}, and J. When just the overall molecular rotation N is considered the PSDs are in remarkable agreement with calculations based on phase space theory (PST). However, when the projection of N onto the molecular frame (K{sub a},K{sub c}) is included the distributions show consistent deviations from PST. In particular, there is a tendency to preserve the initial parent rotational motion about the a and b axes. The effect is that states with higher initial K{sub a} in H{sub 2}CO produce higher final K{sub a} in the HCO fragment. There is also a tendency for the upper/lower members of the asymmetry doublets in H{sub 2}CO to map onto the same upper/lower set of product state asymmetry doublets. Finally, there are oscillations in some of the detailed PSDs that remain unexplained.
- OSTI ID:
- 20722925
- Journal Information:
- Journal of Chemical Physics, Vol. 122, Issue 19; Other Information: DOI: 10.1063/1.1902863; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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