Time-resolved laser magnetic resonance study of deactivation of Cl(2P1/2)

Abstract

Rate constants for the collisional deactivation of spin–orbitally excited Cl* (≡Cl(2P1/2)) atoms by some selected gases have been determined using time-resolved laser magnetic resonance (LMR) techniques. Cl* atoms were produced by photodissociation of ICl at 248 nm, and the relative quantum yield of Cl* atoms is determined to be 0.47±0.06. The rate constants for the relaxation of Cl* (×10−11 cm3/molecule⋅s, ±2σ) by H2(5.5±1.6), HF(1.4±0.4), DF(0.7±0.2), DCl(0.7±0.2), HBr(1.2±0.36), DBr(1.4±0.4), NO(0.66±0.2), SO2 (1.9±0.5), N2O (0.63±0.2), NF3 (22±6), CH4 (1.9±0.6), CD4 (13±4), CF4 (2.4±0.7), SiF4 (14±4), and SF6 (18±5) at 298 K are reported. The rate constants of the reactions of ground state Cl(2P3/2) atoms with HBr and DBr were found to be, in units of ×10−11 cm3/molecule⋅s, 0.75±0.15 and 0.50±0.10, respectively. The study of the deactivation process I(2P1/2)+ICl→Cl*+I2 (a), Cl+I2 (b), I+ICl (c) yielded the ratios ka/(ka+kb)=0.63±0.17, ka/(ka+kb+kc)⩾0.70.