Abstract
Formation of van der Waals clusters of amino-acid tryptophan was investigated by means of seeded supersonic expansion combining with laser desorption technique. Stable van der Waals clusters of tryptophan molecules, (Trp)n up to n=5, were observed in a time-of-flight mass spectrum. No significant difference was observed in the formation of clusters for each enantiomer, i.e., L-, D-, and racemic-tryptophans. Strikingly no dominant van der Waals complexes other than the type of (Trp)n were observed, though weakly bound van der Waals complexes such as a tryptophan·(rare gas)n type are commonly seen in an ordinary seeded beam expansion. The dynamical properties of tryptophan dimers, and trimers in a carrier argon gas were measured by the use of a fast optical imaging device.
