Optogalvanic detection of krypton Rydberg levels with a two-step pulsed laser excitation

Abstract

The authors have used an optogalvanic detection scheme, in conjunction with a two-step pulsed laser excitation, to investigate high-lying (Rydberg) krypton levels. The excitation scheme starts from the metastable 1s5 level, populated in the He-Kr discharge tube and uses either the 2p2 or the 2p3 level as an intermediate level. The transient variation of the voltage across the discharge (duration about 50 mu s) is detected as a function of the second-step laser frequency. The energy of the levels of the odd series nd(3/2)2 and nd(7/2)3 have been measured for n=15 to 25 with an accuracy of 0.03 cm-1. Members of the even series nf(7/2)J, nf(9/2)J and np(5/2)3 have also been identified and the corresponding energies measured. In the latter case, the excitation scheme involves a collisional excitation transfer from the laser populated intermediate levels to the closely lying 3d4' level.