Photodissociation of OCCl2 in the Vacuum Ultraviolet: Production and Electronic Energy of Excited Cl2

Abstract

The photodissociation of OCCl2 in the vacuum ultraviolet yields electronically excited Cl2 producing emission continua in the region 2000–3100 Å. A curve obtained by plotting fluorescence efficiencies as a function of incident wavelength shows diffuse vibrational structure corresponding to the ν 1 symmetric stretching mode of OCCl2, indicating that the process is predissociative. Three main continua at 3063, 2565, and 2460 Å were observed by the photolysis of OCCl2 with the Kr 1236‐Å line, while only one continuum at 2580 Å was obtained by the Xe 1470‐Å line. From threshold energies of the incident photons to produce each continuum it was possible to obtain electronic energies of excited Cl2. Electronic energies thus obtained are 7.21 ± 0.05 eV and 7.93 ± 0.03 eV for the upper states associated with the 2580‐ and 3063‐Å continua, respectively. The electronic energy of the upper state responsible for the 2460‐Å continuum lies between 7.33 and 8.93 eV. The effect of inert gas on the emission continua was investigated. A comparison has been made of the emission continua obtained by the photolysis of OCCl2 and those produced by an electric discharge of Cl2. The absorption coefficient of OCCl2 has been measured in the region 1170–1600 Å.