Optical production of metastable krypton

We have investigated a new scheme for excitation of the 5s, J = 2 metastable level of Kr (5s[3/2](J=2)) which can be readily extended to other rare gases. In the scheme, an ultraviolet (UV) lamp is used to create a population of Kr atoms in the 5s[3/2](J=1) level in a gas cell. The excited atoms are then pumped to the 5p[3/2](J=2) level, using 819 nm light from a Ti:sapphire laser, from which they decay to the metastable state with a branching, ratio of 77%. We made two striking observations: (1) the laser power required to saturate the second step. decreases markedly as a function of gas cell pressure, and (2) the UV photon flux is converted with very high efficiency (approximate to10%) to metastable atom flux. A Monte Carlo study of the scattering: of UV photons. in, the cell reproduces the trends observed.,The understanding achieved points to the design of a higher flux source of metastable atoms.