Photodissociation of nitromethane cluster anions

Journal Article · Sat Aug 28 00:00:00 EDT 2010 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3479586· OSTI ID:21559908

Goebbert, Daniel J; Khuseynov, Dmitry; Sanov, Andrei ^[1]

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1. Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 84721-0041 (United States)

Three types of anionic fragments are observed in the photodissociation of nitromethane cluster anions, (CH{sub 3}NO{sub 2}){sub n}{sup -}, n=1-6, at 355 nm: NO{sub 2}{sup -}(CH{sub 3}NO{sub 2}){sub k}, (CH{sub 3}NO{sub 2}){sub k}{sup -}, and OH{sup -} (k<n). The fragmentation trends are consistent with the parent clusters containing a monomer-anion core, CH{sub 3}NO{sub 2}{sup -}, solvated by n-1 neutral nitromethane molecules. The NO{sub 2}{sup -}(CH{sub 3}NO{sub 2}){sub k} and OH{sup -} fragments formed from these clusters are described as core-dissociation products, while the (CH{sub 3}NO{sub 2}){sub k}{sup -} fragments are attributed to energy transfer from excited CH{sub 3}NO{sub 2}{sup -} into the solvent network or a core-dissociation--recombination (caging) mechanism. As with other cluster families, the fraction of caged photofragments shows an overall increase with increasing cluster size. The low-lying A{sup 2}A{sup '} and/or B{sup 2}A{sup '} electronic states of CH{sub 3}NO{sub 2}{sup -} are believed responsible for photoabsorption leading to dissociation to NO{sub 2}{sup -} based fragments, while the C{sup 2}A{sup ''} state is a candidate for the OH{sup -} pathway. Compared to neutral nitromethane, the photodissociation of CH{sub 3}NO{sub 2}{sup -} requires lower energy photons because the photochemically active electron occupies a high energy {pi}{sup *} orbital (which is vacant in the neutral). Although the electronic states in the photodissociation of CH{sub 3}NO{sub 2} and CH{sub 3}NO{sub 2}{sup -} are different, the major fragments, CH{sub 3}+NO{sub 2} and CH{sub 3}+NO{sub 2}{sup -}, respectively, both form via C-N bond cleavage.

• OSTI ID: 21559908
• Journal Information: Journal of Chemical Physics, Vol. 133, Issue 8; Other Information: DOI: 10.1063/1.3479586; (c) 2010 American Institute of Physics; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ANIONS
CLEAVAGE
DISSOCIATION
DISSOCIATION ENERGY
ELECTRONS
ENERGY TRANSFER
FRAGMENTATION
MOLECULAR CLUSTERS
MOLECULES
MONOMERS
NITRITES
NITROGEN DIOXIDE
NITROMETHANE
PHOTOLYSIS
PHOTONS
RECOMBINATION
SOLVATION
SOLVENTS
BOSONS
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL EXPLOSIVES
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTARY PARTICLES
ENERGY
EXPLOSIVES
FERMIONS
IONS
LEPTONS
MASSLESS PARTICLES
MICROSTRUCTURE
NITRO COMPOUNDS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS