Cluster Formation of Biomolecules in the Gas Phase

Abstract

Supersonic beam expansion with respect to the formation of neutral biomolecular clusters was investigated. Laser desorption (LD) into a supersonic beam was used to form neutral clusters of biomolecules in the gas phase. The internal degrees of freedom of laser desorbed neutral molecules were cooled, allowing for the formation of intermolecular bonds leading to neutral clusters of biomolecules. The clusters were post-ionized by either multiphoton ionization (MUPI), or photo-induced electron 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 investigation of biologically relevant systems, such as [retinoid–amino acid] cluster interactions.