No abstract

The CN(B2Z+-X2Z+) emission spectrum, produced in the dissociative excitation reaction of BrCN with Ar(3Po,2) at thermal collision energy, was observed by using the flowing afterglow method. The effect of collisional relaxation of the excited electronic states of CN by the ground-state Ar atoms was minimized by lowering the ambient argon pressure to less than 10 mTorr. The "nascent" rovibrational distribution of CN(B2Z+) was determined by spectral simulation. A surprisal analysis of the nascent rovibrational distribution of CN(B2Z+) indicated that the dominant pathway of the reaction of BrCN with Ar(3Po,2) was energy transfer, instead of argon complex formation of ion-pair exciplex formation.

On the basis of the Kramers-Henneberger (KH) high-frequency approximation, we carried out an ab initio molecular orbital calculation for He 2 in intense laser fields. The potential energy curve is found to be attractive, indicating that a He-He chemical bond is formed. The formation of the He-He chemical bond is ascribable to changes in the nature of KH molecular orbitals. Intense laser fields cause a kind of sp hybridization of KH atomic orbitals. The degree of the hybridization depends on the internuclear distance, and reaches a maximum at around the equilibrium internuclear distance. This hybridization remarkably strengthens/weakens the bonding/anti-bonding character of the 1σ g /1σ u KH molecular orbitals, respectively.

No abstract

Dissociation dynamics of a sodium cluster ion, Na n ϩ ͑nϭ2-9 and 11͒, in collision with a rare gas atom ͑He or Ne͒ was investigated by measuring the absolute cross sections for the production of fragmented ions by using a tandem mass-spectrometer equipped with several octapole ion guides. The mass spectra of the fragmented ions show that release of Na and/or Na 2 from Na n ϩ occurs dominantly. The absolute total cross section for the dissociation of Na n ϩ and the absolute partial cross sections for the Na and/or the Na 2 release were determined at different collision energies and cluster sizes. The absolute total dissociation cross sections were calculated by a scheme that collisionally excited Na n ϩ dissociates with leaving Na and Na 2 unimolecularly. On the other hand, the partial cross sections for the Na and the Na 2 release were successfully explained by the orbital correlation diagram for the dissociation system; the dissociation channel involving an adiabatic transition was found to be influenced significantly by the collision energy and the cluster size.