Lai-Sheng Wang is currently Professor of Chemistry at Brown University in Providence, Rohde Island. He is an experimental physical chemist known for his work on gold nanoclusters and planar boron clusters. He received his B.S. degree in Chemistry from Wuhan University in 1982 and his Ph.D. in Physical Chemistry from the University of California at Berkeley in 1990. After a postdoctoral stay at Rice University, he took a joint position between Washington State University and Pacific Northwest National Laboratory in 1993, then accepted an appointment as Professor of Chemistry at Brown University in 2009.
Prof. Wang's research focuses on investigation of the size-dependent properties of nanoclusters using photoelectron spectroscopy and computational chemistry. Research in his group has led to the discovery of golden buckyballs and the smallest golden pyramid, as well as aromatic clusters and planar boron clusters. Prof. Wang's group has also pioneered spectroscopic studies in the gas phase of free multiply-charged anions and complex solution-phase anions produced from electrospray ionization. His group has developed cryogenic ion trap techniques to create ultracold ions from electrospray for high resolution spectroscopic investigations. Prof. Wang is an author of more than 380 peer-reviewed publications in the fields of size-selected nanoclusters and chemical physics.
Prof. Wang has received the Alfred P. Sloan Research Fellowship and the John Simon Guggenheim Fellowship. He is a fellow of the American Physical Society and the American Association for the Advancement of Science. He has received the Humboldt Senior Research Award by the Alexander von Humboldt Foundation and the Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics by the American Physical Society.
FROM PLANAR BORON CLUSTERS TO BOROPHENE
Photoelectron spectroscopy in combination with computational studies over the past decade has shown that boron clusters possess planar or quasi-planar structures,1-4 in contrast to that of bulk boron, which is dominated by three-dimensional cage-like building blocks. All planar or quasi-planar boron clusters are observed to consist of a monocyclic circumference with one or more interior atoms. The propensity for planarity has been found to be a result of both ? and ? electron delocalization over the molecular plane, giving rise to concepts of ? and ? double aromaticity. To date, boron clusters with up to 24 atoms have been found to be planar.5 A question arises, to what size will boron clusters remain planar? An even more interesting question is if infinitely large planar boron clusters are possible, giving rise to atom-thin boron nanostructures analogous to graphene.
Boron is carbon’s neighbor in the periodic table and has similar valence orbitals. However, boron cannot form graphene-like structures with a honeycomb hexagonal framework because of its electron deficiency. Computational studies suggested that extended boron sheets with partially filled hexagonal holes are stable, but there has been no experimental evidence for such atom-thin boron nanostructures. Recently, we have shown experimentally and theoretically that B36 is a highly stable quasiplanar boron cluster with a central hexagonal hole, providing the first experimental evidence that single-atom layer boron sheets with hexagonal vacancies are potentially viable. Photoelectron spectroscopy of B36 – reveals a relatively simple spectrum, suggesting a symmetric cluster. Global-minimum searches for B36 – lead to a quasiplanar structure with a central hexagonal hole. Neutral B36 is the smallest boron cluster to have six-fold symmetry and a perfect hexagonal vacancy, and it can be viewed as a potential basis for extended two-dimensional boron sheets, which we named “borophene”.6