Dr. Plusquellic's research interests in the Applied Physics Division center on fully-state resolved studies of biomolecules and chromophores in the microwave (MW), terahertz (THz), and ultraviolet (UV) spectral regions. The THz spectral region provides access to the lowest frequency collective motions of biomolecular systems that are responsible for the large scale conformational changes associated with folding and activation of protein, polynucleotide and polysaccharide backbones. We have pioneered the use of high-resolution THz laser sources to investigate the fully state-resolved vibrational spectra of polypeptides and to characterize the spectral response to hydration of hydrophobic and hydrophilic sites in a wide variety of crystalline structures. We are also developing new instrumentation to enhance the spectral and spatial resolution and sensitivity in this region using waveguides, dual beam and adaptive near-field imaging approaches.
In the near-IR, he is developing methods for accurately quantifying greenhouse gas emissions from natural and anthropogenic sources and sinks to meet the requirements for local, national, and international mitigation efforts. The methods are based on a technology known as differential absorption LIDAR (Light Detection And Ranging), or DIAL, which can provide species specific concentrations of greenhouse gases with range resolution. When these measurements are coupled to precise wind velocity measurements, the flux of the greenhouse gases, the important quantity for regulators, can be determined. Multiple DIAL systems are currently running in parallel for comparison measurements and validation purposes. These include multiple near- and far-field DIAL systems, integrated path differential absorption (IPDA), and a commercial cavity ringdown point sensor. The near-field DIAL system provides comparison with point sensor measurements, and the far-field systems are used to extend the range coverage for comparison with the integrated path retrievals.
Dr. Plusquellic is fellow of the American Physical Society. Other professional associations include membership in American Chemical Society and American Association for the Advancement of Science. He received the NIST Bronze Award in 2010. He has co-authored over 100 technical peer-reviewed papers, delivered over 50 invited talks and holds five U.S. Patents.