Dissociative Excitation Process of BrCN in the ECR Plasmas of Rare Gases

抄録

The dissociative excitation reaction of BrCN with the electron-cyclotron resonance plasma flows of He, Ne, Ar, and Kr was studied based on the electrostatic-probe measurements and on the optical emission spectra of the B²Σ⁺−X²Σ⁺ transition of CN radicals. The electron-energy distributions and the CN(B²Σ⁺−X²Σ⁺) emission intensity were dependent on the addition of H₂O molecules externally into the reaction region. Based on a kinetic analysis, the mechanism of dissociation of BrCN was found, predominantly, to be the electron impact, BrCN+e⁻→Br+CN(B²Σ⁺)+e⁻, in the cases of Ne, Ar, and Kr, whereas dissociation proceeds via the ion-electron recombination, BrCN⁺+e⁻→Br+CN(B²Σ⁺), in the case of He. The difference of the dissociation mechanism is interpreted in terms of the rate constants for the relevant processes.