2-PHOTON IONIZATION OF TRIMETHYLAMINE USING KRF LASER-RADIATION

The multiphoton ionization of a low-pressure (3 X 10(-5) Torr) fill of trimethylamine using an electron-beam pumped KrF laser has been studi ed. A microwave resonator probe was used to measure the resultant free -electron density. The scaling of electron density with the square of the incident laser intensity was verified in the low flux limit. The e lectron production decreased significantly from the 12 scaling at lase r fluxes exceeding 4 MW/cm(2). These results are consistent with a sim ple two-photon model describing the interaction in the low flux limit and a saturation of the electron production in the high-flux limit. (C ) 1996 American Institute of Physics.