The mass spectrometry endstation uses the VUV light from a bending magnet as the ionization source (6-11.6 eV), and several high-resolution mass spectrometer as detectors. This endstation is dedicated to the studies of: 1) in-situ detection of gas-phase desorbed radicals and stable products in heterogeneous catalytic reactions. 2) VUV light-induced activeation and dissociation of proteins and peptides, which is complementary to the results from CID and ECD. 3) photoionization mass spectrometry imaging of living tissues with 100 um lateral resolution.