The Destruction of Metastable Helium Atoms by Collision-Induced Radiation

A calculation has been made of the cross section for destruction of He(2 1 S) metastable atoms by collision-induced radiation in two-body collisions with neutral helium atoms. The four-electron wave functions used for the system were built up from unperturbed atomic orbitals. Assuming the form of interaction between normal and metastable atoms calculated by Buckingham and Dalgarno which exhibits a repulsive barrier of a height of 0.26 eV at separations greater than 2.1 × 10 -8 cm, the calculated cross section was 9 × 10 -26 cm 2 at a temperature of 300° K. However, even if no barrier was assumed the cross section increased only to 5 × 10 -22 cm 2 , still much too small to account for the value of 3 × 10 -20 cm 2 measured by Phelps for the destruction cross section.