Preservation of rotational cooling following pulse compression TOF mass selection of N2O+ ions created in a supersonic plasma

Cold ions created in the dense region of an ionized free jet are mass selected by pulsing them into a tandem time-of-flight (TOF) photofragmentation spectrometer after the plasma breaks up in the 1/r2 expansion. These ions are then refocused for interaction with a pulsed laser to recover the high signal levels typical of ion spectroscopies carried out inside the plasma. The rotational cooling of the N2O+ ion in the source was found to be preserved even after transverse extraction through the unskimmed jet. Details of the cavity stabilized, single mode pulsed dye laser are also presented.