RUI: Electronic Spectroscopy of Vanadium Hydride and Niobium Hydride

WIth support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) Program of the Division of Chemistry, Professor Thomas D. Varberg and his undergraduate student researchers at Macalester College will use visible and near-infrared spectroscopy to study the structure and bonding of two transition metal hydrides, vanadium hydride (VH) and niobium hydride (NbH), in the gas phase.

The molecules will be probed using a combination of laser excitation and dispersed fluorescence spectroscopy to identify low-lying and excited electronic states. Analyses of the spectra will provide values for molecular properties such as the bond length and vibrational frequency. Transition metal chemistry and bonding is important to other areas of modern science, including organometallic chemistry, nanoscience, chemical catalysis, and astronomy.

Detailed studies of metal-containing diatomic molecules are useful for understanding bonding in these more complex systems.

Electronic spectra in the visible and near-infrared will be recorded with a high-resolution continuous-wave laser capable of resolving the vibrational, rotational, and hyperfine structures of the two molecules. Spectral assignment and model fitting will lead to a detailed characterization of the electronic states and the chemical bonding, as well as providing accurate transition frequencies useful to other scientists.

Supporting computational work by collaborator Professor Keith Kuwata and his students, also at Macalester College, will utilize density functional theory to provide accurate estimates of the ground state magnetic dipole and electric quadrupole hyperfine constants. Results will also be compared with multi-configurational self-consistent field (MCSCF) calculations by other workers to test the accuracy of this computational methodology.

A substantial broader impact of this work is to prepare Macalester students, including students from underrepresented groups, for graduate work and employment in the fields of physical chemistry and chemical physics. Accurately determined transition frequencies for vanadium hydride provide an additional broader impact, as VH is a good candidate for astronomical detection in cooler stars or brown dwarfs in our Galaxy.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.