Mass spectrometry of toluene clusters using a laser produced plasma for tunable single photon ionization

Here we report the first operation of a new apparatus of time of flight mass spectrometry using the tunable Vacuum-UV radiation emitted by a laser produced plasma as ionising source. Toluene cluster mass spectra acquired at different ionising wavelength are presented. Due to massive fragmentation the mass spectra change significantly by increasing the photon energy above the toluene ionisation potential. We found that the more reliable information on the cluster distribution can be gained by tuning the photon energy at value slightly higher than the toluene ionisation energy. The results demonstrate that the developed tunable vacuum-UV source can be successfully used as a soft ionisation method in the study of weakly bound complexes as well as of real complex gaseous mixture.