The fluorescence spectra of (a) methane , (b) ethylene , (c) -butane , and (d) 1-butene . The spectra are recorded after the shinning of Ti:sapphire laser pulse at the laser intensity of . For (a), the emission bands at 314.5, 388.9, and are assigned to the , , and transitions of CH radical, respectively. A weak emission of Balmerline at referred to the transitions of H is also observed. For the spectra of (b), (c), and (d), in addition to the CH and H transitions, five bands near 437, 473, 516, 563, and are assigned to the , 1, 0, and progressions of Swan bands , respectively.
Correlation diagram between and its dissociation products. The energy data are from ab initio calculated results (Refs. 15 and 21). The dissociation pathways of the low-lying excited state are shown in the lower part of the diagram. The upper part of the diagram shows the possible dissociation pathways of the superexcited states.
The fine structure of the fragment spectrum of methane. The methane gas is irradiated by intense laser at the laser intensity of . The emission spectrum is assigned to the rotational and vibrational transitions of the CH radical. The spectrum is divided into four parts: (a) 0-0, 1-1, and 2-2 bands of transition; (b) 0-0 and 2-2 bands of transition, (c) 1-0 band of transition; and (d) 0-0 and 1-1 bands of transition.
The laser intensity dependence of the CH fluorescence intensity is shown in the insertion of the plot. The rising slope of the curve is .
Rotational and vibrational temperatures of the CH fragments. The rotational temperatures are estimated from the slope of the plots which are shown in the inserts of the Fig. 3. The vibrational temperatures are estimated by calculating the ratios of the total emission intensities, which are normalized by the Franck-Condon factors.
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