Determination of the vibration-rotation interaction factor for He2transitions

Vibration-rotation interaction coefficients F vJ were calculated for the e 3 Pi g -a 3 Sigma u + and E 1 Pi g -A 1 Sigma u + transitions of He 2 on the basis of a Morse-Pekeris potential and a polynomial expansion of the dipole-moment function M(r)= Sigma i M i (r-r e ) i reduced to the first two terms. Owing to the importance of F vJ they cannot be neglected when determining the rotational temperature of He 2 by spectroscopic methods involving line-intensity measurements.