Bimodal kinetic energy release in the unimolecular dissociation of energy-selected formic acid ion

Journal Article · Sun Oct 01 04:00:00 EDT 1989 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.456831· OSTI ID:5524016

Nishimura, T; Meisels, G G ^[1]; Niwa, Y ^[2]

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1. Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0304 (US)
2. Basic Research Division, National Chemical Laboratory for Industry, Tsukuba-city, Ibaraki 305 Japan

Dissociation of HCOOH{sup +} and DCOOH{sup +} have been studied using threshold photoelectron--photoion coincidence (TPEPICO) mass spectrometry. The detailed breakdown diagrams were obtained over internal energies of the molecular ion less than 8 eV. Kinetic energy release distributions (KERDs) for HCO{sup +} and DCO{sup +} were extracted from their flight time distributions by using a multiple linear regression method. The breakdown curve of HCO{sup +} not only exhibited several maxima but also the surprisal analysis of its KERD demonstrated a considerable deviation from a single statistical distribution. Bimodal KERDs were observed for the formation of HCO{sup +} and DCO{sup +}. The large KER component results from dissociation to the products in the ground state, HCO{sup +} ({sup 1}{Sigma}{sup +})+{center dot}OH ({sup 2}{Pi}{sub {ital i}}). Average kinetic energy releases observed for this process are, however, about twice higher than those calculated by QET/RRKM. The small KER component shows average KERs remarkably smaller than the statistical expectations and this value remains constant over the energy range of 4.5 eV. The origin of this small KER component was ascribed to dissociation after fluorescent transition of initial vibronic states to the first excited state (1 {sup 2}{ital A}{double prime}). In contrast with these results average KERs measured for H{sub 2}O{sup +} and HDO{sup +} are in good agreement with the RRKM/QET calculations.

• OSTI ID: 5524016
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 91:7; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACYL RADICALS
CARBOXYLIC ACIDS
CHARGED PARTICLES
CHEMICAL REACTION YIELD
DISSOCIATION
ELECTRON SPECTROSCOPY
ENERGY
FORMIC ACID
FORMYL RADICALS
IONS
KINETIC ENERGY
MASS SPECTROSCOPY
MOLECULAR IONS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
RADICALS
SPECTROSCOPY
YIELDS