Mark H. Thiemens

Mark H. Thiemens is a Distinguished Professor of Chemistry and Biochemistry at the University of California San Diego, with a career spanning over four decades of groundbreaking research in isotope chemistry. Affiliated with both the Department of Chemistry and Biochemistry and the Scripps Institution of Oceanography, Professor Thiemens has established himself as a world leader in the field of mass-independent isotope fractionation.

Professor Thiemens' research focuses on the fundamental chemical and physical processes that govern isotope fractionation, with applications spanning atmospheric chemistry, cosmochemistry, geochemistry, and planetary science. His work bridges experimental, theoretical, and observational approaches to understand isotopic signatures in natural systems. The Thiemens Isotope Laboratory develops and applies cutting-edge analytical techniques to measure subtle isotopic variations that serve as fingerprints for specific chemical processes.

His recent publications reveal a continued focus on photodissociation isotope effects, lunar and Martian water studies, and applications to Earth's climate system. The 2024 review article celebrating 40 years of research demonstrates how his discoveries have evolved from fundamental laboratory observations to tools used across multiple scientific disciplines.

Selected Honors:

• Member, National Academy of Sciences
• Arthur L. Day Medal, Geological Society of America
• F.W. Clarke Medal, Geochemical Society
• Fellow, American Academy of Arts and Sciences
• Fritz London Memorial Prize in Low Temperature Physics

Professor Thiemens actively mentors graduate students and postdoctoral researchers, many of whom have gone on to successful careers in academia and research institutions. His laboratory maintains strong collaborations with NASA centers, international research institutions, and multiple departments across UC San Diego. Current research projects include studies of extraterrestrial materials, atmospheric processes relevant to climate change, and the development of new isotopic techniques for planetary exploration.