Collision broadening in the strontium resonance line, lambda 4607 AA

The profile of the strontium resonance line lambda 4607 AA formed in absorption in an atmosphere of helium and of argon at pressures of up to one atmosphere has been determined, together with the corresponding shift of the line centre. The results for both the impact and static regions of the profile are interpreted in terms of interatomic potentials of the Lennard-Jones type. The results for argon give a van der Waals coefficient C6 in good agreement with theoretical estimates and provide further confirmation of line broadening theory for both parts of the profile. A discrepancy in the case of broadening by helium suggests that the curvature of collision paths may be important in this case.