Photoionization spectrum of 85RbCs molecules produced by short range photoassociation

•RbCs85 molecules in J=1, v=8, (2)Π0−3 state are produced by locking PA laser with transfer cavity technique in a space-adjustable dark SPOT.•Photoionization spectrum of aΣ+3 ground state are presented and analyzed.•The population distribution of aΣ+3 state distributing in the range of v=0-29 vibrational states is calculated.•An enlarged PI spectrum with relative clear peaks is assigned to v=24-33 vibrational levels of (1)Σ+2 state.

We present photoionization (PI) spectrum of ultracold ground state 85RbCs molecules formed by spontaneous decay from J=1, v=8 rovibrational level of (2)Π0−3 short range excited state molecules, which are produced from a space-adjustable dark spontaneous force optical trap. PI spectrum is obtained by scanning PI laser when photoassociation laser is locked by utilizing transfer cavity technique based on an ultrastable He-Ne laser as a reference laser. We calculated vibrational distribution of RbCs molecules in metastable ground state and corresponding transition probabilities to RbCs+ ion in (1)Σ+2 state. An enlarged PI spectrum with relative clear peaks is assigned to v=24-33 vibrational levels of molecular ion state. The method we used in PI spectrum analysis is also adoptable for other states of RbCs molecules or other kinds of molecules.