The current configuration of the cryo-SEVI instrument is shown in Figure . Anions are generated using a pulsed molecular beam combined with either an electron impact ionizer or a Smalley-type laser ablation source. Recently, Wang and co-workers have coupled an electrospray source to a cryo-SEVI instrument. In our experiment, the anions pass through a series of ion optics including a skimmer held at a repulsive voltage, a collimating radiofrequency (RF) hexapole, and a mass-selecting RF quadrupole, before entering a RF octupole ion trap held at 5 K. Ions spend 40 ms in the trap, where they are cooled to roughly 10 K via collisions with helium buffer gas before being extracted from the trap into a Wiley-McLaren mass spectrometer. After traveling along a perpendicular time-of-flight path, the ions of interest are photodetached inside a seven-plate VMI spectrometer by a pulsed laser beam from a dye laser. In IR cryo-SEVI experiments, the tunable infrared laser used to pre-excite the anions is spatially and temporally overlapped with the photodetachment pulse, as this configuration was found to give the highest IR-induced signals.