This paper proposes a novel one-colour Xe-Kr laser induced collisional ionization system. Considering the level scheme of the system, it finds that the initial state of the reaction—the four 4f levels with even J of Xe—can be prepared through method of four-photon resonant excitation by dye laser with wavelength of ～440 nm. Absorption of an additional photon (the transfer laser) of the same wavelength will complete the laser induced collisional ionization process. The resonance enhanced ionization spectrum of Xe by four laser photons at ～440 nm is measured through time-of-flight mass spectrometry, this aims at the preparation of the initial state of the system proposed. The Stark broadening of the measured spectrum is observed and consistent with the previous study. Analysis of the measured resonance ionization spectrum implies the feasibility of ～440 nm four-photon resonant excitation of the initial 4f state of the Xe-Kr system proposed in this paper, which prepares for a further experiment of laser induced collisional ionization.
The four-level model of laser-induced collisional energy transfer(LICET) for the ion-ion collision system is established based on the time-dependent Schro¨dinger equation for the electron dynamics,through which the equations of motion of the probability amplitudes and cross section of the collision system are obtained.Numerical calculations are performed for the Ca+-Sr+ system,with the results showing that the peak of the LICET spectrum appears at a resonant frequency of the transfer laser.The magnitude of the obtained collision cross section is in the order of 10 16 cm2,and is comparable to that obtained in atomic systems,which indicates the validity of the established four-level model.
