The Internal Rotation & Intermolecular Vibration And Binding Energy In Van Der Waals Complex C₆H₅CH₃…N₂,Ar

Many experiments of van der Waals complexes which consist of relatively large aromatic molecules bound to rare-gas atoms or small molecules have been studied. Van der Waals(vdW) complexes are weak bonding complexes formed by atoms or molecules through interaction of electric multipole moments and dispersion forces. These complexes are characterized by their comparatively low binding energy (100-1000cm-1). During the last two decades , great interest has been aroused in the study of weak bonding complexes, as it can provide detail information on intermolecular properties such as multipole moments .interaction potentials, etc., which are highly important for us to understand the macroscopic physical and chemical properties of matter .Moreover ,the complexes of this kind are ideal objects for studying the processes of intermolecular energy transference, vibrational relaxation and predissociation which are the bases for studying macroscopic phenomena .In this paper ,we study the vdW (C6H5CH3...N2 Ar) vibrations in complexes by using a combined experiment and theoretical studies of resonant ionization spectra. For complexes, vdW vibration levels are calculated by the quantum method of linear -combination of three-dimensional harmonic oscillator products and Lennard-Jones potential, which is very close to the experimental spectrum . In our experiments, these complexes, produced in supersonic beam expansions, are amenable to high resolution resonant two-photons ionization spectroscopy, which make it possible to obtain detailed information on their electronic -vibrational states. Through resonant ionization spectra and together with time-of-flight mass spectrometry in supersonic molecular beam, the internal rotation for CH3 and intermolecular vibration for atom Ar (or N2) in the complexes (C6H5CH3... Ar N2) are exhibited . we obtain the complete information and a whole microscopic picture of the intermolecular actions and relative motions of these complexes .All observed bands are rationally assigned by isotope effect and calculated at the internal rotational levels and external vibrational levels are obtained.By comparing the spectra of isotopic complex C6D5CD3...N2, we have tentatively assigned all the observed spectral features to the complex C6H5CH3...N2.The binding energies for the complexes C6H5CH3...N2 in the excited electronic state and in the ground electronic state are about 494cm-1 and 474cm-1,which are very close to the calculated values. A experimental and theoretical studies of resonant ionization spectra for van der Waals complexes C6H5CH3...Ar and C6D5CD3...Ar are also reported. The internal rotation for CH3 and intermolecular vibration for atom Ar in the complexes are exhibited.The internal rotational levels .external vibrational levels and three modes frequencies of van der Waals vibrations for complexes C6H5CH3...Ar are obtained.