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 l aser for desorption of neutral molecules, followed by a pulsed, tunabl e UV laser for resonant multiphoton postionization is described. The i nnovative features of this instrument are the following: spatially res olved desorption in the mum range, a simple and efficient ion extracti on geometry, and several improvements in sample loading, positioning, and observation. Excellent sensitivity in the attomole range and a mas s resolution of M/DELTAM almost-equal-to 2000 are demonstrated. Primar y applications include spatially resolved organic trace analysis and t he detection of selected chemical compounds in complex mixtures.