FEMTOSECOND TIME-RESOLVED COHERENT ANTI-STOKES-RAMAN SCATTERING OF THE C-EQUIVALENT-TO-C STRETCHING IN LIQUID ALKYNES

Femtosecond time-resolved coherent anti-Stokes Raman scattering has been observed from the C=C stretching of alkynes (monoalkylacetylenes and dialkylacetylenes). The dephasing of the C=C stretching Of C3H7C=CH is found to be accelerated in mixtures with either proton-donors or proton-acceptors. The dephasing rates of the C=C stretching of monoalkylacetylenes (CnH2n+C=CH) with relatively long alkyl chains (n greater-than-or-equal-to 4) are nearly the same and are accelerated in mixtures with dimethylformamide regardless of the length of the alkyl chain. On the other hand, the dephasing in dialkylacetylenes is not accelerated in mixtures with dimethylformamide, reflecting the absence of hydrogen bonding between dialkylacetylenes and dimethylformamide.