State specific reactions of Ba([sup 1][ital S][sub 0]) and Ba([sup 1][ital D][sub 2]) with water and methanol

Journal Article · Mon Jun 14 20:00:00 EDT 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.464390· OSTI ID:6513016

Davis, H F; Suits, A G; Lee, Y T ^[1]; Alcaraz, C; Mestdagh, J ^[2]

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1. Chemical Sciences Division, Lawrence Berkeley Laboratory and Department of Chemistry, University of California at Berkeley, Berkeley, California 94720 (United States)
2. Service des Photons, Atomes, et Molecules, CE de Saclay, 91191 Gif-sur-Yvette (France)

The reactions of Ba(6[ital s][sup 2] [sup 1][ital S][sub 0]) and Ba(6[ital s]5[ital d] [sup 1][ital D][sub 2]) with water and methanol were studied under single collision conditions using crossed molecular beams. Reaction of ground state Ba([sup 1][ital S])+H[sub 2]O led to dominant formation of BaO+H[sub 2] at all collision energies studied (12--30 kcal/mol). Although the reaction Ba([sup 1][ital S])+H[sub 2]O[r arrow]BaOH+H could also be observed at collision energies above the endoergicity of the reaction (13 kcal/mol), it remained a minor channel even at the highest collision energy. Electronic excitation of the Ba atom reactant to the metastable [sup 1][ital D][sub 2] state led to a large enhancement in reactivity, but the products were BaOH+H rather than BaO+H[sub 2]. The dominance of BaO+H[sub 2] from ground state Ba([sup 1][ital S]) even at collision energies nearly equal to the Ba([sup 1][ital D]) excitation energy of 11 395 cm[sup [minus]1] ([similar to]32 kcal/mol) indicates that the observed reaction state specificity results from participation of different potential energy surfaces for reactions of ground and excited state atoms. Collisions of Ba([sup 1][ital S]) and Ba([sup 1][ital D]) with methanol led only to formation of BaOCH[sub 3]+H. We observed no BaOH+CH[sub 3] or BaO+CH[sub 4], despite the fact that they are the more thermodynamically favorable channels. Although reactivity with methanol was strongly enhanced by electronic excitation of the incident Ba atom, no reaction was observed from Ba([sup 1][ital S]) or Ba([sup 1][ital D])+dimethyl ether (CH[sub 3]OCH[sub 3]). These observations strongly suggest that the reactions leading to radical formation involve H-atom migration.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6513016
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 98:12; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALCOHOLS
ALKALINE EARTH METALS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
BARIUM
BEAMS
CHEMICAL REACTIONS
COLLIDING BEAMS
COLLISIONS
D STATES
DIFFUSION
ELECTRON SPECTRA
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
GROUND STATES
HYDROGEN
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
METALS
METASTABLE STATES
METHANOL
MOLECULE COLLISIONS
NONMETALS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PRODUCTION
RADICALS
S STATES
SPECTRA
WATER