e/f Parity Dependence of Rotational Energy Transfer Cross Sections for CO（A¹Π）

Absolute rotational energy tranfer cross sections for CO A¹Π（v=3,J=3～16） are measured in a thermal cell via the ultrasensitive Optical-Optical Gouble Resonance Multiphoton Ionization technique.He、Ne、Ar、HCl、CO₂ are used as collision partners.The propensity rule of parity-conservation are obviously observed in all our studied energy transfer processes.The exponential energy gap law is used to fit the experimental data satisfactorily.The parity-conservation propensity is explained by Alexander and Davis’s inelastic inelastic scattering theory.For the parity-inversion processes we found an abnormality of σ_ΔJ^e→f=0＜σ_ΔJ^e→f=±1 for the collision partners He/Ne, which is in contrast with σ_ΔJ^e→f=0＞σ_ΔJ^e→f=±1 for the partners of Ar、HC1、CO₂ The abnomality of σ_ΔJ^e→f=0＜σ_ΔJ^e→f=±1,which is inconsistent with the energy gap law,has been ascribed to the orbital-overlap interaction between colliders.