Ultraviolet light-induced atom desorption for large rubidium and potassium magneto-optical traps

We show that light-induced atom desorption (LIAD) can be used as a flexible atomic source for large Rb87 and K40 magneto-optical traps. The use of LIAD at short wavelengths allows for fast switching of the desired vapor pressure and permits experiments with long trapping and coherence times. The wavelength dependence of the LIAD effect for both species was explored in a range from 630 to 253 nm in an uncoated quartz cell and a stainless steel chamber. Only a few mW cm2 of near-UV light produce partial pressures that are high enough to saturate a magneto-optical trap at 3.5× 109 Rb87 atoms or 7× 107 K40 atoms. Loading rates as high as 1.2× 109 Rb87 atoms/s and 8× 107 K40 atoms/s were achieved without the use of a secondary atom source. After the desorption light is turned off, the pressure quickly decays back to equilibrium with a time constant as short as 200 μs, allowing for long trapping lifetimes after the MOT loading phase.