Abstract
CCl~2~ free radicals were produced by a pulsed dc discharge of CCl~4~ in Ar. Ground electronic state CCl~2~(X) radicals were electronically excited to the A^1^B~1~ (0,4,0) vibronic state with an Nd:YAG laser pumped dye laser at 541.52 nm. Experimental quenching data of excited CCl~2~(A^1^B~1~ and a^3^B~1~) by O~2~, N~2~, NO, N~2~O, NH~3~, NH(CH~3~)~2~, NH(C~2~H~5~)~2~, and N(C~2~H~5~)~3~ molecules were obtained by observing the time‐resolved total fluorescence signal of the excited CCl~2~ radical in a cell, which showed a superposition of two exponential decay components under the presence of quencher. The quenching rate constants k~A~ of CCl~2~(A) state and k~a~ of CCl~2~(a) state were derived by analyzing the experimental data according to a proposed three‐level model to deal with the CCl~2~(X^1^A~1~, A^1^B~1~, a^3^B~1~) system. The formation cross sections of complexes of electronically excited CCl~2~ radicals with O~2~, N~2~, NO, N~2~O, NH~3~, and aminated molecules were calculated by means of a collision‐complex model. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 351–356, 2002