We use electrospray ionization to bring ions from solutions into the gas phase. The ions enter the vacuum apparatus of the instrument through a desolvation capillary. They are then transferred through a series of octopole ion guides into a high vacuum chamber, where they are injected into a temperature controlled (T = 10 - 300 K) Paul trap. After entering the trap, the ions cool down in collisions with cold buffer gas, before being ejected into the acceleration region of a time-of-flight mass spectrometer. Here, the ions are mass-separated and then mass-selected using a pulsed mass gate. After mass selection, the ions are irradiated with light from a nanosecond-pulsed, tunable optical parametric converter system operating either in the near UV and visible range, or in the infrared. Fragment ions generated by photon absorption and subsequent photodissociation are analyzed in a second mass spectrometry step, using a reflectron. The fragment ion intensity is monitored as a function of the photon energy, yielding a photodissociation spectrum.
Cryogenic Ion Spectroscopy
Experimental Research in the Weber Group.