Clusters of organic molecules in a supersonic jet expansion

A wide variety of clusters were obtained in seeded supersonic conical jet expansions of organic molecules. It was shown that mixed clusters probably are formed statistically in the collisional region of the expansion, although kinetic effects cannot be excluded. The molecular fragmentation in the clusters upon mass selection using electron impact ionization is negligible, which makes the use of supersonic jet expansions under cluster forming conditions a valuable addition to standard mass spectrometry analytical techniques. The effect of the electron impact ionization on cluster fragmentation was studied.