CHINESE JOURNAL OF PHYSICS VOL. 26. NO. 5 DECEMBER 1988 Excited Chlorine Atoms Produced from Photodissociation of Cl2 with Vacuum Ultraviolat Radiation J. B. Nee ( E @j h ) Department of Physics, National Central University Chung-Li, Taiwan 32054 (Received August 31, 1988) Photodissociation of Cl2 molecules in the wavelength region smaller than 110 nm produces strong emissions in the ultraviolet and the vacuum ultraviolet as observed previously. We show in this paper that the vacuum ultraviolet emission results from generation of electro- nically excited chlorine atoms, and the ultaviolet emission from molecular chlorine. That the parent state responsible for this process is a triplet state is discussed. I. INTRODUCTION The higher excited states of chlorine molecules have recently received much attention. By means of synchrotron radiation the absorption spectrum in the 105-140 nm wavelength region has been determined. The spectrum consists of prominent features due to both Rydberg states and ion-pair ?tates2e3. The fluorescence originating from these states is quite strong as discussed in these publications. Theoretical calculations on the higher excited states of chlorine molecule have also been recently published by Peyerimhoff and Buenker4 and Grein et. a1.5. They provide useful guidance for the interpretation of experimental data. In general the agreement between the theoretical calculations and the experimental results is quite good. The ground state of the chlorine molecule has the electron configuration: . (Q3SY (a 3s)2 (as3pY &3p)” (7r,3pY briefly written as (a,) (n,)” (T,)~. The excitation of the as electron into higher Rydberg orbitals 4pn( 1 z : state) and 4pa(? n siate)produced strong emissions in the ultraviolet (UV. h > 200nm) and vacuum ultraviolet (VUV. X < 200nm) region as discussed in Ref. 1-3. 254