Vibrationally Resolved Photofragment Translational Spectroscopy of CH3I from 277 to 304 nm with Increasing Effect of the Hot Band
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文摘
The photodissociation dynamics of CH3I from 277 to 304 nm is studied with our mini-TOF photofragment translational spectrometer. A single laser beam is used for both photodissociation of CH3I and REMPI detection of iodine. Many resolved peaks in each photofragment translational spectrum reveal the vibrational states of the CH3 fragment. There are some extra peaks showing the existence of the hot-band states of CH3I. After careful simulation with consideration of the hot-band effect, the distribution of vibrational states of the CH3 fragment is determined. The fraction 蟽 of photofragments produced from the hot-band CH3I varies from 0.07 at 277.38 nm to 0.40 at 304.02 nm in the I* channel and from 0.05 at 277.87 nm to 0.16 at 304.67 nm in the I channel. Eint/Eavl of photofragments from ground-state CH3I remains at about 0.03 in the I* channel for all four wavelengths, but Eint/Eavl decreases from 0.09 at 277.87 nm to 0.06 at 304.67 nm in the I channel. From the ground-state CH3I, the quantum yield 桅(I*) is determined to be 0.59 at 277 nm and 0.05 at 304 nm. The curve-crossing probability Pcc from the hot-band CH3I is lower than that from the ground-state CH3I. The potential energy at the curve-crossing point is determined to be 32鈥?40 cm鈭?.