Molecular dynamics simulations of laser disintegration of amorphous aerosol particles with spatially nonuniform absorption

A series of molecular dynamics (MD) simulations are performed in order to p rovide qualitative information on the mechanisms of disintegration of aeros ol particles as used in aerosol mass spectrometry. Three generic types of a erosol particles are considered: strongly absorbing particles with homogene ous composition, transparent particles with absorbing inclusion, and absorb ing particles with transparent inclusion. To study the effect of the mechan ical properties of the aerosol material on the disintegration process, the results for crystalline (brittle) and amorphous (ductile) particles are com pared. For large laser fluences, nearly complete dissociation of the absorb ing material is observed, whereas the nonabsorbing portions remain fairly i ntact. Because large fluences can cause photofragmentation of constituent m olecules, multiple pulses at low laser fluence and/or lasers with different wavelengths are recommended for the best representative sampling of multic omponent aerosol particles in laser desorption/ionization (LDI) mass spectr ometry. (C) 2001 Elsevier Science B.V. All rights reserved.