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A multiphoton ionization study of the photodissociation dynamics of the S_2 state of CH_3ONO

Winniczek, J. W. and Dubs, R. L. and Appling, J. R. and McKoy, V. and White, M. G. (1989) A multiphoton ionization study of the photodissociation dynamics of the S_2 state of CH_3ONO. Journal of Chemical Physics, 90 (2). pp. 949-963. ISSN 0021-9606. doi:10.1063/1.456120.

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Two‐color (1+1) REMPI (resonantly enhanced multiphoton ionization) photoelectron spectroscopy is used to probe the NO photofragments produced by the UV photodissociation of methyl nitrite, i.e., CH_3ONO+hν→CH_3ONO∗(S_2)→CH_3O⋅(X)+NO(X, v, J). The photofragments are produced in their ground electronic states but with high rotational and translational energy. NO fragment angular distributions, rotational state distributions, and spatial alignment are determined by photoion and photoelectron detection. The initial state alignment is obtained by the CDAD (circularly dichroic angular distribution) technique for the first time. CDAD measurements for rotational levels with 35.5≤J≤46.5 result in alignment parameters at the classical high‐J limit of A^(2)_0 =−0.4. This alignment is consistent with an ‘‘impulsive’’ dissociation mechanism in which photofragment recoil along the CH_3O–NO bond imparts substantial rotational angular momentum to the NO molecule resulting in a high‐J state distribution and preferential rotation in the plane of dissociation. These measurements clearly establish the utility of the CDAD method for probing chemical processes in which spatial alignment plays an important role. Photoion angular distributions are used to probe correlations between the CH_3ONO transition dipole moment, NO fragment velocity, and angular momentum. These correlations reveal additional details of the photolysis mechanism.

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Additional Information:© 1989 American Institute of Physics. Received 1 August 1988; accepted 14 October 1988. J.W.W. and M.G.W. would like to thank Dr. Greg Hall for helpful discussions. The research at Brookhaven National Laboratory was supported under Contract No. DEAC02-76CH00016 with the U.S. Department of Energy and by its Division of Chemical Sciences, Office of Basic Energy Sciences. Work at the California Institute of Technology was supported by grants from the National Science Foundation (CHE-8521391 ), Air Force Office of Scientific Research (Contract No. 87-0039), and the Office of Health and Environmental Research of the U.S. Department of Energy (DE-FG03-87ER60513). R.L.D. and V.M. also acknowledge the use of the resources of the San Diego Super Computer Center, which is supported by the National Science Foundation.
Funding AgencyGrant Number
Department of Energy (DOE)DE-AC02-76CH00016
Air Force Office of Scientific Research (AFOSR)87-0039
Department of Energy (DOE) Office of Health and Environmental ResearchDE-FG03-87ER60513
Issue or Number:2
Classification Code:PACS: 82.50.Bc; 82.50.Hp; 33.60.+q; 33.80.Rv; 33.80.Gj
Record Number:CaltechAUTHORS:20120530-153101110
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Official Citation:A multiphoton ionization study of the photodissociation dynamics of the S2 state of CH3ONO J. W. Winniczek, R. L. Dubs, J. R. Appling, V. McKoy, and M. G. White J. Chem. Phys. 90, 949 (1989);
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:31727
Deposited By: Ruth Sustaita
Deposited On:30 May 2012 23:07
Last Modified:09 Nov 2021 19:59

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