Photodissociation spectroscopy of ClCN in the vacuum ultraviolet region

The quantitative photofragment fluorescence spectroscopy, using the synchro tron radiation as an exciting light source, was applied to study the Rydber g and high-lying valence states of ClCN observed as congested structures in the vacuum ultraviolet region. The absolute cross-section and quantum yiel d for the CN(B (2)Sigma(+)-X(2)Sigma(+)) emission produced in the photodiss ociation 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(2)Sigma(+)) product ion takes a maximum value of approximate to 0.13 at approximate to 84 000 c m(-1). The emission of CN(B (2)Sigma(+)-X(2)Sigma(+)) transition was found to be partially polarized with respect to the direction of the electric vec tor of the excitation synchrotron radiation. The polarization anisotropy of this emission, which depends on the symmetry of absorption transitions int o the photodissociative states of ClCN was measured as a function of exciti ng wavelength. The relative cross-section for the production of CN(A (2)Pi( i)-X(2)Sigma(+)) emission was also determined. Based on the measured photoc hemical properties of the high-energy electronic states, the observed bands of the Rydberg and intravalence transitions are assigned. (C) 2000 Elsevie r Science B.V. All rights reserved.