A high resolution time-of-flight mass spectrometer for the detection of ultracold molecules

We have realized a high-resolution time-offlight mass spectrometer combined with a magneto-optical trap. The spectrometer enables excellent optical access to the trapped atomic cloud using specifically devised acceleration and deflection electrodes. The ions are extracted along a laser beam axis and deflected onto an off axis detector. The setup is applied to detect atoms and molecules photoassociated from ultracold atoms. The detection is based on resonance-enhanced multi-photon ionization. Mass resolution up to m/∆mrms = 1000 at the mass of Cs is achieved. The performance of this spectrometer is demonstrated in the detection of photoassociated ultracold LiCs molecules near a large signal of Cs ions.