Optical pumping of trapped neutral molecules by blackbody radiation

Optical pumping by blackbody radiation is a feature shared by all polar molecules and fundamentally limits the time that these molecules can be kept in a single quantum state in a trap. To demonstrate and quantify this, we have monitored the optical pumping of electrostatically trapped OH and OD radicals by room-temperature blackbody radiation. Transfer of these molecules to rotationally excited states by blackbody radiation at 295 K limits the 1/e trapping time for OH and OD in the X-2 Pi(3/2), v('')=0, J('')=3/2(f) state to 2.8 and 7.1 s, respectively.