Thiel earned her bachelor’s degree in chemistry at Macalester College in 1975, where she graduated summa cum laude, and her Ph.D. in chemistry at the California Institute of Technology in 1981, where she won the highest award available to graduating Ph.D. students in chemistry. After postdoctoral work at the University of Munich as an Alexander von Humboldt Fellow, she joined the technical staff at Sandia National Laboratories at Livermore, then moved to Iowa State University in 1983, where she spent the next 37 years. Her scientific research earned many recognitions, including the David J. Adler Lectureship Award from the American Physical Society, the Arthur W. Adamson Award from the American Chemical Society and a National Science Foundation Presidential Young Investigation Award. She authored or edited more than 350 scientific publications. She served on numerous boards and committees for major scientific organizations, including editorial advisory boards for ten journals. For six years, she served as associate editor of the Journal of Chemical Physics, one of the premier scientific journals in her field.
At Iowa State, she supervised the thesis research of approximately 30 Ph.D. students and ten Master’s students. She took great pride in her students and her role as a teacher.