Thermal beam of metastable krypton atoms produced by optical excitation

A room-temperature beam of krypton atoms in the metastable 5s[3/2](2) level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce vacuum ultraviolet photons at 124 nm for the first-step excitation from the ground level 4p(6) S-1(0) to the 5s[3/2](1) level. An 819 nm Ti:sapphire laser is used for the second-step excitation from 5s[3/2](1) to 5s[3/2](2) followed by a spontaneous decay to the 5s[3/2](2) metastable level. A metastable atomic beam with an angular flux density of 3x10(14) s(-1) sr(-1) is achieved at the total gas flow rate of 0.01 cm(3)/s at STP (or 3x10(17) at./s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.(c) 2007 American Institute of Physics.