Abnormal behavior inthe three-photon resonance enhanced multiphoton ionization spectroscopy of CO E~1#PI# - X~1#SIGMA#~+ (0,0)

摘要

The abnormal behavior of CO E~1#PI#(#upsilon#=0) <- X~1#SIGMA#~+ (#upsilon#=0) three-photon resonace enhanced multiphoton ionization (REMPI) sepctroscopy is studied, including the anomalos band structures and adverse pressure effects onthe spectral intensity. One- and two-color experiments with laser beams in co- and counterpropagations have been performed to elucidate the mechanisms. It is demonstrated that the abnormalities originate from two mechanisms, i.e., the reabsorption of the resultant third harmoinc generation (THG) inthe one-color case or gour wave mixing sum frequency generation (FWSFG) inthe two-color case, and the interference cancellation betweenthe one-kphoton excitation channel induced by THG/FWSFG reabsorption and the three-photon direct excitation channel. The former mechanism dominate inthe wing region of a resonant transition profile, while the latter is rstricted within the kernel portion of the transition.