Hydrated clusters of organic molecules generated by IR OPO resonant desorption of frozen aqueous solutions

Long series of hydrated clusters of organic molecules (formaldehyde, methanol, ethanol and tryptophan) have been generated by infrared optical parametric oscillator (OPO) resonant desorption of frozen aqueous solutions. Using a comparative approach, we derived some general trends from cluster size and velocity distribution measurements. In the biologically interesting case of tryptophan amino acid, our technique yields a much longer (and complete) series of hydrated clusters than that obtained previously using a combined laser desorption/pulsed jet expansion technique [L.C. Snoek, R.T. Kroemer, J.P. Simons: Phys. Chem. Chem. Phys. 4, 2130 (2002)].