Laser photolysis of ICl. A time-resolved LMR measurement of Cl(²P _{1 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 (IC1) molecules. The ²P _{1 2} (F′, M′ = 2, 2) ← ²P _{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 β = [Cl(²P _{1 2})]₀/ ([Cl(²P _{3 2})]₀ + [Cl(²P _{1 2})]₀) following IC1 photolysis within the wavelength range 437 < λ < 532 nm and at λ = 266 nm. The maximum relative yield of excited Cl atoms (0.79 ± 0.03) was measured at λ = 480 ± 0.5 nm. At λ = 266 nm the relative yield was 0.65 ± 0.06. These experimental data combined with measured relative yields of Cl(²P _{1 2}) in the dissociation from the B ³Π₀₊ state were used to decompose the visible absorption spectrum into two components. The extinction coefficient is represented as the sum of two Gaussian components: ε{lunate}_{1 max} = 105.8 ± - 1 ℓ mol^-1 cm^-1' ε{lunate}_{2 max} = 63 ± 2 mol^-1 cm^-1; v₀₁ = 21070 ± 13 cm^-1; v₀₂ = 24077 ± 27 cm^-1; Δv₁ = 1901 ± 18 cm^-1; Δv₂ = 2087 ± 49 cm^-1 (1 and 2 refer to the transitions B ³Π₀₊ ← X ¹Σ₀₊ and ¹Π ← X ¹Σ₀₊, respectively, T = 298 K). The main absorption is due to the transition B ³Π₀₊ ← X ¹Σ₀₊.