Collisional recycling of excited atomic populations in Ca in a thermionic diode following pulsed-laser excitation of a metastable state
Muhammad Arshad Khan, M.A. Gondal, M. H. Rais
Experimental results are reported where the rates of collisional energy transfer in optically prepared atomic metastable states are considerable compared with the rate of normal radiative decay. A remarkable consequence is a large increase in the effective lifetime of some excited states lying above the optically prepared state. The specific case of calcium is presented here as an example where over a 1000-fold increase in the lifetime of 4s3d 3 D states has been experimentally measured following pulsed-laser pumping of 4s4p 3 P 1 metastable state. This can have important applications in the development of quasi-CW lasers. The possibility of populating 4s4p 1 P 1 and 4s5s 3 S 1 states through energy pooling collisions is also investigated. The rate coefficient for pooling to the 4s5s 3 S 1 state is estimated to be 10 -8 -10 -9 cm 3 s -1 .
Journal of Physics B Atomic Molecular and Optical Physics•Jul 28, 1994•12 citations