Temperature measurement of ultracold molecules by time evolution of photoionization signal

A simple and reliable method is used for the temperature measurement of ultracold molecules prepared in a magnetooptical trap (MOT). This method is based on the case where the initial distribution of an atomic or molecular sample is a Gaussian function of position and velocity. The atoms or molecules are detected by a sensitive photoionization detection technique. We obtain the temperature of molecules by analyzing the evolution of a photoionization signal. We compare the results of atomic temperature with the measurements by the release recapture technique (R&R), and find reasonable agreement. This provides a complementary method of determining the temperature of ultracold atoms and molecules. (C) 2014 The Japan Society of Applied Physics