Production and Detection of Ultracold Ground State ⁸⁵Rb¹³³Cs Molecules in the Lowest Vibrational Level by Short-Range Photoassociation

We investigate the production of ultracold ground state X¹Σ⁺(ν=0) RbCs molecules in the lowest vibrational level via short-range photoassociation followed by spontaneous emission. The starting point is the laser cooled ⁸⁵Rb and ¹³³Cs atoms in a dual species, forced dark magneto-optical trap. The special intermediate level (5)0⁺(ν=10) correlated to the (2)³Π electric state is achieved by the photoassociation process. The formed ground state X¹Σ⁺(ν=0) molecule is resonantly excited to the 2¹Π intermediate state by a 651 nm pulse laser and is ionized by a 532 nm pulse laser and then detected by the time-of-flight mass spectrum. Saturation of the photoionization spectroscopy at large ionization laser energy is observed and the ionization efficiency is obtained from the fitting. The production of ultracold ground state ⁸⁵Rb¹³³Cs molecules is facilitative for the further research about the manipulation of ultracold molecules in the rovibrational ground state.