Trapping and quenching of potassium resonance radiation

Abstract

The effects of imprisonment of resonance radiation in potassium vapor and of collisions between excited potassium atoms and N 2 , H 2 , HD, and D 2 molecules, on the measured lifetimes of the 4 2 P states, have been investigated by the method of delayed coincidences. The potassium atoms were excited with short pulses of resonance radiation, and the delays between the exciting and fluorescent pulses were measured with a time-to-amplitude converter. At pure potassium densities below 10 10 atoms/cm 3 , the measured lifetimes approach the constant values 27.8 ± 0.8 and 27.6 ± 0.8 ns, corresponding to the natural lifetimes of the 4 2 P 1/2 and 4 2 P 3/2 states, respectively. At higher densities the effective lifetimes are in satisfactory agreement with the predictions of Holstein's theory. The decrease in the measured decay rates observed upon addition of the diatomic gases yielded cross sections for quenching collisions with N 2 , H 2 , HD, and D 2 which equal 34.0 ± 2.0 Å 2 , 9.4 ± 1.3 Å 2 , 11.9 ± 1.5 Å 2 , and 8.0 ± 2.0 Å 2 , respectively.