PNNL

Dr. Michael Wilhelm is a molecular spectroscopist in the Spectroscopy and Analysis Team at Pacific Northwest National Laboratory (PNNL). His research focuses on the acquisition and interpretation of infrared spectral signatures. In additional to measurements, he routinely employs density functional theory and rotational contour analysis to quantitatively model measured spectra.

Prior to joining PNNL, Wilhelm served as a Research Assistant Professor at Temple University, where he developed nonlinear laser light scattering and imaging methods (e.g., second-harmonic generation) to quantify molecular interactions at the surfaces and buried interfaces of colloidal objects. His work in this area led to breakthroughs in characterizing antimicrobial mechanisms, quantifying membrane transport kinetics in living cells, and redefining the molecular mechanism of the Gram-stain protocol.

Wilhelm also specializes in time-resolved Fourier transform infrared emission spectroscopy to study transient species (e.g., radicals, unstable isomers) and deactivation of vibrationally excited molecules. His recent work investigates the UV photolysis of cyano-containing molecules to explain the astrophysical overabundance of hydrogen isocyanide.

Wilhelm earned his PhD in chemistry from the University of Pennsylvania, followed by an NIH NRSA postdoctoral fellowship at the Perelman School of Medicine. His research has been featured in C&E News and Science News, and has appeared on the covers of numerous journals, including ACS Chemical Biology, Biophysical Journal, and Accounts of Chemical Research.

• Molecular spectroscopy
• Nonlinear optics
• Physical chemistry
• Biophysics of membranes
• Antibiotics
• Photodissociation dynamics
• Radicals and molecular transients

• PhD in chemistry, University of Pennsylvania
• BS in chemistry, Rowan University
• BA in mathematics, Rowan University

Hai-Lung Dai, Mohammad Sharifian, Michael J. Wilhelm. 2026. Gram-Stain Differentiation with Nonlinear Light Scattering. US Patent 12,578,271, filed November 12, 2021, and issued March 17, 2026.

• International Filings: EP21892917.2A (Europe) and CN202180088294.6A (China), filed November 12, 2021. Status: Pending.

Google Scholar Link

2025

• Wilhelm M.J., M.M. Herzog, R.G. Tonkyn, M. Howard, T.J. Johnson, and P. Sawyer. 2025. "In Situ Atmospheric Plume Thermometry via Carbon Monoxide Spectral Profile: Laboratory and Field Validation." ACS Earth and Space Chemistry 9, no. 3:513-523. PNNL-SA-199336. doi:10.1021/acsearthspacechem.4c00289

2024

• Forland B.M., K.D. Hughey, M.J. Wilhelm, O.N. Williams, B.F. Cappello, C.L. Gaspar, and T.L. Myers, et al. 2024. "Optimal Spectral Resolution for Infrared Studies of Solids and Liquids." Applied Spectroscopy 78, no. 5:486-503. PNNL-SA-189798. doi:10.1177/00037028241231601
• Forland B.M., K.D. Hughey, M.J. Wilhelm, O.N. Williams, B.F. Cappello, C.L. Gaspar, and T.L. Myers, et al. 2024. "Optimal spectral resolution for solids and liquids using FT and other infrared spectrometers: How much resolution do you really need?." In Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXV, SPIE Defense + Commercial Sensing, April 21-26, 2024, National Harbor, MD. Proceedings of the SPIE, edited by J.A. Guicheteau, C.R. Howle and T.L Myers, 13053, Paper No. 130561A. Bellingham, Washington:SPIE (International Society for Optical Engineering). PNNL-SA-197396. doi:10.1117/12.3013359
• Lockwood S., B.E. Bernacki, M.J. Wilhelm, T.L. Myers, T.J. Baker, and T.J. Johnson. 2024. "Modeling Aerosol Transmission Spectra from n(?) and k(?) Infrared Optical Constants Measurements of Organic Liquids and Solids." Optics Express 32, no. 17:30169-30181. PNNL-SA-198270. doi:10.1364/OE.529439

2023

• Baker T.J., R.G. Tonkyn, C.J. Thompson, M.K. Dunlap, P. Koster Van Groos, N.A. Thakur, and M.J. Wilhelm, et al. 2023. "An infrared spectral database for gas-phase quantitation of volatile per- and polyfluoroalkyl substances (PFAS)." Journal of Quantitative Spectroscopy and Radiative Transfer 295. PNNL-SA-177601. doi:10.1016/j.jqsrt.2022.108420
• Lonergan C.E., J.D. Erickson, M.K. Kelly-Gorham, O.M. Primera-Pedrozo, M.J. Wilhelm, B.M. Forland, and K.D. Hughey, et al. 2023. "Using synthetic infrared spectra derived from n/k optical constants for standoff detection of chemical deposits." In Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XXIV; SPIE Defense + Commercial Sensing, April 30-May 5, 2023, Orlando, FL. Proceedings of the SPIE, edited by J.A. Guicheteau and C.R. Howle, 12541, Paper No. 1254109. PNNL-SA-184155. doi:10.1117/12.2663579
• Wilhelm M.J., T.J. Johnson, and T.L. Myers. 2023. "Disentangling the Confounding Spectroscopy of C1 Molecules: Without Symmetry as a Guide, Everything is Allowed." AIP Advances 13, no. 5:Art. No. 055133. PNNL-SA-180822. doi:10.1063/5.0155054

2022

• Myers T.L., B.E. Bernacki, M.J. Wilhelm, K.L. Jensen, T.J. Johnson, O.M. Primera-Pedrozo, and R.G. Tonkyn, et al. 2022. "Influence of Intermolecular Interactions on the Infrared Complex Index of Refraction for Binary Liquid Mixtures." Physical Chemistry Chemical Physics 24, no. 36:22206-22221. PNNL-SA-173808. doi:10.1039/D2CP02920K