Professor Bowen's research interests are centered around clusters and nanoparticles. Clusters
are aggregates of atoms and/or molecules held together by some of the same interatomic or
intermolecular forces which are responsible for cohesion in solids and liquids. Clusters are
thus finite-size microcosms of the condensed phase, the realm in which most chemistry occurs.
A major objective of Dr. Bowen's research is to provide a molecule's eye view of many-body,
condensed phase interactions. The study of size-specific and composition-specific clusters
provides an incisive means of addressing this fundamental and longstanding problem in
physical chemistry.
For technical reasons, clusters are best studied as negatively-charged species. Experimental
methods utilized in Dr. Bowen's group to study clusters include both continuous and pulsed
negative ion photoelectron spectroscopy, mass spectrometry, and photodissociation
spectroscopy. This work is instrumentally oriented, with major components of their several ion
beam apparatus including both continuous and pulsed lasers, high vacuum systems, ion and
electron optics, electronics and computers, as well as time-of-flight, quadrupole, magnetic
sector, and Wien fliter mass spectrometers. The training in advanced instrumentation, afforded
students in Dr. Bowen's group, lays a firm foundation for careers in either physical or
analytical chemistry. Experimental emphasis is also placed on designing unique sources of
cluster ions and on the preparation and characterization of nanoparticles for a variety of
technological applications, such as catalysis.
A particularly attractive aspect of cluster studies concerns the very wide variety of scientific
problems that can be addressed, stretching from the edge of biology, through chemistry and
condensed matter physics, to the edge of astrophysics. Using the versatile techniques described
above, Dr. Bowen's group is studying (or has studied) the number of water molecules
necessary to induce the formation of zwitterions in amino acids, the energetics of electron
capture in hydrated nucleic acid bases, the solvent-induced stabilization of otherwise unstable
organic anions, the solvation of anions by aqueous and non-aqueous solvents, the energetics
and growth paths of charged atmospheric aerosols, the microscopic conditions necessary for
forming solvated electrons, the stability of color centers in nanocrystals of metal compounds,
the insulator-to-metal transition in clusters of divalent metals, the electronic structure of alkali
metal clusters, the prospects for magic clusters as building blocks of futuristic
cluster-assembled materials, the nature of exotic species such as dipole bound and double
Rydberg anions, and the role of nanoclusters in interstellar dust. The opportunity to be involved
in such a diversity of fields is an exciting and satisfying aspect of this work for Dr. Bowen and
his research group.