© IUPAC APPLICATIONS OF LASERS IN CHEMICAL SPECTROSCOPY AND DYNAMICS: HIGHER ORDER SUSCEPTIBILITY EFFECTS

Abstract — A survey of recent experiments on molecular excited states will be presented. Many non-linear optical processes have now become extremely useful in chemical spectroscopy and dynamics. Laser E—fields induce a dipole moment 1 in molecular systems which in turn acts as a source of additional fields in the medium. The polarization is generally a power series in the fields: NP=X E+X EE+X EEE+.... Normally, centrosmetric molecules have = 0 and systems that are centrosyinmetric will not generally exhibit second harmonic generation. (2).Thus the study of x in such cases has provided information on the magnetically induced SHG. This effect coupled with the two—photon absorption, a resonant part of was used to explore polariton effects in molecular crystals of anthracene and naphthalene. High resolution spectroscopy of gases and solids were also accomplished using three wave mixing brought about through two—photon and Raman resonances in