Professor Parmenter's research in chemical physics has centered on a fundamental aspect of chemical reactivity, namely how excitation energy flows among molecular energy levels. His development of single vibronic level fluorescence spectroscopy provided the way to see how isolated molecules respond to selective vibrational excitation as well as a means for reliable vibrational assignments of electronic absorption spectra. It also opened a now widely used approach to state-to-state collisional energy transfer in large molecules. With these tools, he found that energy flow rates have an unexpectedly high sensitivity to vibrational excitation, and he discovered that collisional vibrational energy transfer is governed by strong propensity rules. His development of chemical timing fluorescence spectroscopy gave an early measure of the picosecond time scales for collision-free vibrational energy flow within excited molecules. Professor Parmenter's more recent efforts include crossed molecular beam probes of collisional rovibrational energy transfer and study of the mechanisms underlying energy flow between molecular energy levels.
Recognition of Parmenter's achievements includes a number of awards such as Guggenheim and Fulbright Fellowships, a Humboldt Prize in 1984 from West Germany, selection by English scientists as the 1983 Spiers memorial Lecturer and Medalist, and in 1995 the Earl K. Plyler Prize of the American Physical Society. He is a member of the National Academy of Sciences and a Fellow of the American Academy of Arts and Sciences.
Professor Parmenter served for many years as the faculty advisor of the Chemistry Honors Program and of Alpha Chi Sigma, a professional chemistry fraternity. His teaching was recognized early in his career with the 1968 Indiana University Distinguished Teaching Prize sponsored by Standard Oil of Indiana. In 1989, he won the Sonneborn Award. He has also received the 1990 College of Arts and Sciences Distinguished Faculty Award.
Parmenter received the IU Bicentennial Medal in September 2020 in recognition of his distinguished contributions to Indiana University.