Photodissociation spectroscopy of ClCN in the vacuum ultraviolet region

Abstract

The quantitative photofragment fluorescence spectroscopy, using the synchrotron radiation as an exciting light source, was applied to study the Rydberg and high-lying valence states of ClCN observed as congested structures in the vacuum ultraviolet region. The absolute cross-section and quantum yield for the CN(B 2Σ +–X 2Σ +) emission produced in the photodissociation process of ClCN were determined in the wavelength range 105–145 nm (69 000–95 200 cm −1). The quantum yield for the CN(B 2Σ +) production takes a maximum value of ≈0.13 at ≈84 000 cm −1. The emission of CN(B 2Σ +–X 2Σ +) transition was found to be partially polarized with respect to the direction of the electric vector of the excitation synchrotron radiation. The polarization anisotropy of this emission, which depends on the symmetry of absorption transitions into the photodissociative states of ClCN was measured as a function of exciting wavelength. The relative cross-section for the production of CN(A 2Π i –X 2Σ +) emission was also determined. Based on the measured photochemical properties of the high-energy electronic states, the observed bands of the Rydberg and intravalence transitions are assigned.