Electronic transitions induced by simultaneous absorption of synchrotron radiation and laser

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1. A synchrotron radiation-laser combination technique developed at UVSOR in Okazaki was employed for probing ionic photofragments produced in the vacuum ultraviolet. N^2_+(X^2Σ^g_+, vx=0 and 1) resulting from direct ionization or autoionization of N_2 or N_2O was detected by laser induced fluorescence excitation spectroscopy in the wavelength region of the B^2Σ^u_+←X^2Σ^g_+ transition. The rotational distribution of N^2_+ is determined by the change in the rotational quantum number in photoionization and by the partitioning of the excess energy impulsively released in dissociation.2. A similar combination technique was employed to observe CN radicals produced from CH_3CN.The laser induced fluorescence signal was measured as a function of the photon energy ranging from 13.6 to 18.6 eV with the laser wavelength for the CN(B^2Σ^+, vb=0←X^2Σ^+, v^x=0) transition. The onset of 15.4 eV of the fluorescence signal indicates that the CN(X^2Σ^+)radicals result from dissociative ionization of CH_3CN.3. Photofragmentation of OCS in the excitation photon energy range of 15-30eV was studied by dispersed fluorescence spectroscopy using synchrotron dadiation. The following emission band systems were identified : OCS^+_Ω[A^2II_Ω (0, 0, 0)→X^2II (0, 0, v_3")], CO^+(A^2II X^2II), CS^+(B^2Z^+ A^2II ) and Co(d^3 a^3II). All the transitions of S[nd^3D^o 4p^3→P_e(n=6-9)]which result from neutral dissociation of superexcited Rydberg states of OCS into S(nd^3D^o)+CO.