A systematic study of ion and cluster ion formation in continuous supersonic planar plasma

A systematic mass spectrometric survey has been performed to study ionic species that are formed in continuous supersonic planar plasma. The plasma is generated by electron impact ionization of gas that is expanded supersonically through a long and narrow slit. A quadrupole mass spectrometer is used to sample the adiabatically cooled plasma downstream for different precursor mixtures. The number of different ions and cluster ions formed in the plasma is remarkably large. Densities are sufficiently high to monitor rovibrational transitions in direct absorption by tunable diode laser spectroscopy, using concentration modulation and a phase sensitive detection scheme.