Pressure broadening and shift of He(2 3P0,1,2)-He(2 3S) lines -: art. no. 022714

The collisional broadening and shift of metastable helium fine-structure lines are calculated within the impact approximation. Ab initio Born-Oppenheimer potential energy curves correlating to He(1 S-1(0)) and He(2 P-3(j)) atomic levels are obtained using the configuration interaction valence bond method and combined with semiempirically calculated van der Waals interaction terms between these atoms to also study j-specific and j-changing collisions. A long-range van der Waals potential well exists in the (3)Pi(u) potential correlated to the He(1 S-1(0))+He(2 P-3(j)) limit, whose influence on the scattering phase shift is assessed. At T=310 K, the broadening and shift parameters are practically j independent and have average values of 12.60 and 1.87 MHz/Torr, respectively. The j-changing collisions have cross sections roughly five times smaller than the j-specific cross sections.