CLUSTER FORMATION OF BIOMOLECULES IN THE GAS-PHASE

Supersonic beam expansion with respect to the formation of neutral bio molecular clusters was investigated. Laser desorption (LD) into a supe rsonic beam was used to form neutral clusters of biomolecules in the g as phase. The internal degrees of freedom of laser desorbed neutral mo lecules were cooled, allowing for the formation of intermolecular bond s leading to neutral clusters of biomolecules, The clusters were post- ionized by either multiphoton ionization (MUPI), or photo-induced elec tron impact ionization (PEI), before detection in a reflectron time-of -flight mass spectrometer (RETOF-MS). Seeding small molecules, such as water and benzene, into the jet resulted in cluster formation during the supersonic expansion, Intermolecular forces strong enough to form and stabilize [biomolecule-biomolecule] clusters permitted the investi gation of biologically relevant systems, such as [retinoid-amino acid] cluster interactions.