DESORPTION IONIZATION OF ORGANIC-COMPOUNDS STUDIED BY FOURIER-TRANSFORM LASER MICROPROBE MASS-SPECTROMETRY

The recently developed FT LMMS with an external ion source has been ap plied to selected organic molecules. Some aspects of the ion formation processes from solids under focused laser irradiation at 266 nm were investigated. Specifically, the effect of laser energy and the time pr ofile of ion production were studied. First, the generation of intact cations, fragments and thermal decomposition products from a quaternar y ammonium salt were evaluated at distinct times after the laser pulse . The mass spectra of phenol red in its neutral and salt form were rec orded under different conditions with respect to laser irradiation pow er density conditions and ion formation after the laser pulse. The res ults allow the refinement of previous concepts about ionization in LMM S.