Laser Desorption of Organic Compound Ions from a Silicon Surface Modified by Laser Irradiation

Laser desorption of organic compound ions from specially prepared surfaces is known as surface-assisted laser desorption/ionization (SALDI). In this work the properties of a SALDI ion emitter obtained by two-stage laser treatment of crystalline silicon surface have been investigated. The laser surface treatment leads to the formation of a layer with nanoscale objects—quantum dots (QDs) less than 10 nm in size, providing laser desorption of organic compound ions. A change in the desorbing laser wavelength from 351 to 263 nm at comparable laser-exposed spot sizes and fluences results in a sharp decrease in the formation efficiency for MH + ions and appearance of ions M + for the same analytes. The effect is apparently determined by the spectral properties of the quantum dots formed on the silicon surface under laser irradiation.