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 ⁸⁷Rb and ⁴⁰K 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 6300.3em0exto0.3em0ex2530.3em0exnm 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 ⁸⁷Rb atoms or 7×10⁷ ⁴⁰K atoms. Loading rates as high as 1.2×10⁹ ⁸⁷Rb atoms/s and 8×10⁷ ⁴⁰K 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 2000.3em0exμs, allowing for long trapping lifetimes after the MOT loading phase.