Collision-induced Rotational Energy Transfer Quantum Interference Effects In Theoretical Research

In this dissertation we are reporting our study on Collision Quantum Interference (CQI) effect. Collisional quantum interference takes place in radiationless transitions and is inherently the interference between de Broglie waves. Sha, Zhang and co-workers [J. Chem. Phys. 102, 2772 (1995)] derived a CQI formula, which embodies an interference phase angle, for the cross section of energy transfer between singlet-triplet mixed states. Using optical-optical double resonance multiphoton ionization, they observed CQI for the fist time in energy transfer within mixed states of CO A1п(v = 0)/e3∑-(v =1). Chen et. al also observed the collisioanl quantum interference in the Na2A1∑+u(v = 8) -b3п0u,(v = 14) system collision with Na (3s).The principle results obtained in this Ph. D thesis are that we firstly derived the method of calculating interference angle theoretically, and obtained the relationships between the interference angles with the corresponding experimental conditions. The calculated values are consistent with the experimental results very well. Then we extended the theoretical model in atom-diatom system to the system in polar diatom-diatom system. We took some experiments using OODR-MPI technique in the static cell for the preparation of the experiment in the molecular beam. The detailed results are listed as follows:1. We presented the theoretical model of collisional quantum interference on rotational energy transfer in atom-diatom system, using the theories of time dependent Born approximation and quantum inelastic scattering, and taking into account the long-range interaction potentials. The key factors in the determination of the differential and integral interferenceangles are obtained. CO A1∏ (v = 0) ~ e3 ∑-(v = l) system in collision with He is calculated, the calculated values are consistent withthe experimental results, but for the partners being Ne and Ar, the calculated values are not so good. The main reason is that the short-range potential is ignored.2. We presented the theoretical model of collisional quantum interference on rotational energy transfer in atom-diatom system, using the theories of time dependent Born approximation and quantum inelastic scattering, and taking into account not only the long-range interaction potentials, but also short-range interaction potential. Using the modified theoreticalmodel, CO A1∏(v = 0) ~ e3∑-(v = l) system in collision with Neand Ar is calculated, the calculated values are consistent with the experimental results. The calculated values are consistent with experimental results.3. The potentials of the long-range interactions are much different for the system in the atom-diatom [V∝R (t )-6], and that in diatom-diatom[ V ∝ R(t)-3], so the interference effects are different theoretically. Sowe presented the theoretical model in the polar diatom-diatom system. With the increase of the interaction potentials, the interference will decrease. This model can direct our experiment taking on.4. We attempted to carry out the experiment of CO a3(v = 18) /D1(v = 10) collision with He in a static cell using OODR-MPItechnique for the preparation of doing experiment in a molecular beam machine. In the experiment of 2+1'+1' two-color REMPI, weconformed the accidental predissociation of CO (E1,v = l) state, and studied the effect of the accidental predissociation of CO (E1, v = 1) state for different rotational states. Due to the presence ofaccidental predissociation as well as competition between dissociation and ionization), the accurate measurement of collisional rotational energy transfer with the interference effect became very difficult.