Collision broadening and satellite bands in the potassium line 4047 Angstrom perturbed by krypton

Abstract

The profile of the absorption line 4 2S1/2-5 2P1/2, λ 4047 Angstrom, broadened and shifted by krypton pressures of up to 1 atmosphere, has been determined by means of a high-resolving-power plane-grating spectrograph with a sensitive photoelectric detection system. Both the impact core of the line and the quasi-static red wing, which shows a satellite band, have been interpreted in terms of a Lennard-Jones interaction potential. It is shown that a consistent interpretation of both the core and the red wing can be achieved. The force constants of the potential V(r) = C12e/r12 - C6e/r6 for the excited state 5 2P1/2 of potassium and the ground state of krypton are found from the measurements to be C6e = 6·2 × 10-57 erg cm6 and C12e = 1·4 × 10-99 erg cm12. Simple theories give C6e = 4·1 × 10-57 erg cm6 and C12e = 3·4 × 10-98 erg cm12 and the agreement represented by these values is in line with what has been achieved in earlier attempts to determine interatomic force constants from measurements of collision broadening and shift.