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 monoatomic (He, Ne, Ar) and diatomic (H-2, N-2) collision partners at temperatures of 77 K and 470 K. Via a new data processing approach, theta(ST) is fitted more accurately than earlier approximations. Our experimental results show that theta(ST) increases with the polarizability of monoatomic collision partners, while for diatomic collision partners theta(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 excited CO and N-2 or H-2 has been discussed.