A new time-of-flight (TOF) mass spectrometer incorporating post-ionization of sputtered neutral species with tunable vacuum ultraviolet (VUV) light generated by a free electron laser (FEL) has been developed. Capabilities of this instrument, called SPIRIT, were demonstrated by experiments with photoionization of sputtered neutral gold atoms with 125 nm light generated by the VUV FEL located at Argonne National Laboratory (ANL). In a separate series of experiments with a fixed wavelength VUV light source, a 157 nm F-2 laser, a useful yield (atoms detected per atoms sputtered) of about 12% and a mass resolution better than 1500 were demonstrated for molybdenum. (C) 2004 Elsevier B.V. All rights reserved.