“…LEMS employs an intense (~10 13 W/cm 2 ) femtosecond laser pulse to induce nonresonant vaporization of a sample. Since there is no matrix to absorb the laser energy, fragmentation may be expected with LEMS from the intense pulses; however, intact molecular ions are typically detected, as demonstrated for small biomolecules [1,2], proteins [4][5][6], lipids [7], explosives [8][9][10], smokeless powders [11], narcotics [12], pharmaceuticals [12], and tissues [13,14]. The internal energy distribution can be determined by measuring the fragmentation yield as a function of collision-induced dissociation energy in a series of thermometer ions via the survival yield method [15].…”