LASER PHOTOLYSIS OF ICL - A TIME-RESOLVED LMR MEASUREMENT OF CL(2P1/2) RELATIVE YIELD

Tunable dye laser-pulsed photolysis combined with time-resolved laser magnetic resonance spectroscopy was used to probe Cl atoms after photodissociation of iodine monochloride (ICl) molecules. The P-2(1/2) (F', M' = 2, 2) <-- P-2(3/2) (F'', M'' = 3, 3) transition between Zeeman sublevels of the fine structure levels of Cl atoms was used to measure the relative yield of excited chlorine atoms beta = ([Cl(P1/2)]0)-P-2/(([Cl(P3/2)]0)-P-2 + ([Cl(P1/2]0)-P-2) following ICl photolysis within the wavelength range 437 < lambda < 532 nm and at lambda = 266 nm. The maximum relative yield of excited Cl atoms (0.79 +/- 0.03) was measured at lambda = 480 +/- 0.5 nm. At lambda = 266 nm the relative yield was 0.65 +/- 0.06. These experimental data combined with measured relative yields of (Cl(P1/2)-P-2) in the dissociation from the B 3PI0+ state were used to decompose the visible absorption spectrum into two components. The extinction coefficient is represented as the sum of two Gaussian components: epsilon1max = 105.8 +/- 1 l mol-1 cm-1; epsilon2max = 63 +/- 2 l mol-1 cm-1; nu01 = 21070 +/- 13 cm-1; nu02 = 24077 +/- 27 cm-1; DELTAnu1 = 1901 +/- 18 cm-1; DELTAnu2 = 2087 +/- 49 cm-1 (1 and 2 refer to the transitions B 3PI0+ <-- X 1SIGMA0+ and 1PI <-- X 1SIGMA0+, respectively, T = 298 K). The main absorption is due to the transition B3PI0+ <-- X 1SIGMA0+.