Intersystem crossing in collisions of aligned Ca(4s5p 1P)+He: A half collision analysis using multichannel quantum defect theory

A half collision analysis of alignment effects on intersystem crossing in the collisions of Ca(4s5p 1P) with He has been performed using generalized multichannel quantum defect theory (MCQDT). The theory provides a rigorous analytical representation of the numerically exact closed-coupled scattering wave functions. The half collision analysis results in a factorization of the full quantum collision problem into a number of simpler quantum mechanical problems which reflect different regions of development during the collision. A WKB-assisted, frame transformation approximation to the incoming half collision matrix is tested numerically and is found to be useful in projecting out information on the ‘‘locking radius’’ concept.