C-2 free radicals were produced by photolysis of selected precursors (C2Cl4) with the focused output from the fourth harmonic of a Nd: YAG laser at 266 nm. The generated C-2 (a(3)&UPi;(u)) radicals were then electronically excited to the d(3)&UPi;(g) state with a Nd: YAG laser pumped dye laser at 516.5 nm in the (0,0) band of the C-2 (d(3)&UPi;(g) ← a(3)&UPi;(u)) transition. The rate constants k(q) and averaged collision cross sections aq for collision quenching of C-2 (d(3)&UPi;(g)) by n-CnH2n+2 (n = 1-8) and CH4-nCln (n = 2-4) were measured at room temperature (298 K) by time-resolved laser-induced fluorescence in cell at total pressure of about 15 Torr. Formation cross sections of complexes for the C-2 (d(3)&UPi;(g)) and quenchers were calculated by means of a collision complex model. It was shown that the quenching rates of C-2 (d(3)&UPi;(g)) by alkane molecules increase with the number of C-H bonds of the molecules, which is in agree with that of the measured quenching cross sections. © 2005 Elsevier B.V. All rights reserved.