A NEW INSTRUMENT FOR SPATIALLY-RESOLVED LASER-DESORPTION LASER MULTIPHOTON IONIZATION MASS-SPECTROMETRY

A new reflectron time-of-flight mass spectrometer using a pulsed CO2 laser for desorption of neutral molecules, followed by a pulsed, tunable UV laser for resonant multiphoton postionization is described. The innovative features of this instrument are the following: spatially resolved desorption in the mum range, a simple and efficient ion extraction geometry, and several improvements in sample loading, positioning, and observation. Excellent sensitivity in the attomole range and a mass resolution of M/DELTAM almost-equal-to 2000 are demonstrated. Primary applications include spatially resolved organic trace analysis and the detection of selected chemical compounds in complex mixtures.