FOREIGN GAS BROADENING AND SHIFT IN THE LEAD RESONANCE LINE AT LAMBDA = 283.3 NM

Collision broadening and shift due to low pressures of argon and helium were measured for the absorption profile of the lead resonance line Pb I 283.3 nm. Data interpretation took place by means of the Lindholm-Foley 'impact theory' of collision broadening. In the case of argon perturbers this led to a van der Waals coefficient of: C6 = 4.7(3) x 10(-65) J cm6. For helium a Lennard-Jones (12-6) interaction potential could be deduced with: C6 = 0.7(2) x 10(-65) J cm6 C12 = 5(3) x 10(-108) J cm12. An interpretation in terms of cross sections for collision broadening sigma(r) and shift sigma(i) yielded: argon/lead: sigma(r) = 34(1) x 10(-15) cm2 sigma(i) = 24(1) x 10(-15) cm2 (red shift) helium/lead: sigma(r) = 16(2) x 10(-15) cm2 sigma(i) = 3(1) x 10(-15) cm2 (blue shift).