The effects of CH stretching excitation on the F + CHD3 → HF + CD3 reaction are studied experimentally using crossed-beam and time-sliced velocity map imaging techniques at the collision energy of 9.0 kcal/mol. The fraction of the vibrationally excited CHD3 reagent in the crossed-beam region was determined accurately, allowing us to investigate quantitatively the effects of CH stretching excitation on the title reaction. Experimental data show that the vibrational energy in the excited CH bond of CHD3 is almost exclusively deposited into the HF product vibration, and hence, the HF products from the excited-state reaction are about one vibrational quantum hotter than those of the ground-state reaction, while the vibrational state distribution of the CD3 products is only slightly affected. The reaction is suppressed by the CH stretching excitation, and the overall reactivity of the vibrationally excited reaction is 74 ± 4% of that of the ground-state reaction for CD3(ν2 = 0, 1, 2, 3) product channels.
Keywords: mode-selective chemistry; molecular reaction dynamics; polyatomic reaction; time-sliced imaging; vibrational excitation effect.