FURTHER STUDY ON COLLISIONAL QUANTUM INTERFERENCE EFFECT IN ENERGY-TRANSFER WITHIN CO SINGLET-TRIPLET MIXED STATES

In our previous study [G-H Sha, J-B. He, B. Jiang, and C-H. Zhang, J. Chem. Phys. 102, 2772 (1995)], a concept of interference phase angle ( theta(ST)) has been formally introduced to define the coherence effect between singlet and triplet energy transfer channels for mixed states . In this contribution, we have measured theta(ST) for various monoato mic (He, Ne, Ar) and diatomic (H-2, N-2) collision partners at tempera tures of 77 K and 470 K. Via a new data processing approach, theta(ST) is fitted more accurately than earlier approximations. Our experiment al results show that theta(ST) increases with the polarizability of mo noatomic collision partners, while for diatomic collision partners the ta(ST) is significantly higher than that for monoatomic ones. theta(ST ) at 470 K for He and Ne is higher than that of 77 K, while an adverse temperature effect on theta(ST) has been found for N-2. The influence of intermolecular potential and possible complex formation between ex cited CO and N-2 or H-2 has been discussed. (C) 1996 American Institut e of Physics.