Photon Dissociation Dynamics And Ions Spectroscopy Of Small Molecular Based On XUV Laser

The molecular superexcited states have very strong non-adiabatic interactions. Neutral dissociation is an important decay channel of superexcited states. Because the detection of neutral fragments is more difficult than that of charged fragments, studies of neutral dissociation dynamics are scarce. The pump-probe method is a powerful tool for the neutral dissociation research.The spectra and structure of molecular ions serve as the basic toolforstudying the chemical reaction dynamics, plasma physics, and interstellar molecules. The high resolution zero kinetic energy (ZEKE) photoelectron spectroscopy is a very good tool to study high resolution spectra of ions.Basing on tunable XUV/VUV laser, ZEKE spectra and velocity map imaging methods, we have studied the decay dynamics of superexcited O2and spectra of H2S+Some important results have been obtained.Theneutral dissociation process: O2+hv�'O(3Pj)+O((4S0)3s,5S0)/O((4So)3s,5S0) in the photon energy range14.263-15.200eV has been studied with the XUV pump-UV probe method. The fragment yield spectra of O (5S) and O (3S) were recorded. From the simulation of the yield spectra, we have obtained the vibration energies, rotational constants and line-widths of the spectra. The translational energy distributions and angular distributions of fragments O (5S) and O (3S) have been determined from their velocity map images. Thepotential energy curves for the relevant electronic states have been calculated usingab initio method. The mechanism of neutral dissociation has been discussed based on the experimental and theoretical results.In the range of14.263-15.200eV, O2is excited into the superexceted states:I(1πu-1(a4Πu)4sσg3Πu), I’(1πu-1(a4Πu)3dδg3Πu, and I"(1πu-1(a4Πu)3dσg3Πu). These superexcited states will interact with the vibrational continuum ofRydberg stateF (1πg-1(X2Πg)3pσu3Πu) via electrostatic perturbation leading to the formation of O(3P)+O(5S), and will also interact with the vibrational continuum of Rydberg state H(1πu-1(a4Πu)3sσg3IIu)leading to the formaton ofO(3P)+O(3S).The ZEKE spectrum of H2S has been measured in the photon energy range10.415-12.369eV. The first adiabatic ionization energy (IE=8443l.8±l.Ocm-1), symmetric stretching vibrational frequency (v1+=1160.6cm-1), and bending vibrational frequency (v2+=2495.6cm-1) have been determined. We also obtained the vibrational energy levels, rotational constants, bond lengths and bond anglesfor the vibrational bands (v1+=0-3,v2+=1-14,0). The ZEKE spectrum of H2S has also been measured in the region of the A2A1←X1A1transition band in12.800-13.920eV. The vibrational energy levels, rotational constants, bond lengths and bond anglesfor A(0,1,0)K+=3, A(0,2,0)K+=0-1, A(0,3,0)K+=2, A(0,6,0)K+=0-3, A(0,7,0)K+=0, A(0,8,0) K+=0-l, A(0,9,0)K+=0-1, and A(0,10,0)K+=0-1bands have been determined. We discussed the drastic changes of the K-band structure of bending vibrationsbasedon the ab initioadiabatic potential energy curves of X2B1and A2A1states.