Upon finishing his PhD, he spent a year conducting post-doctoral research at the University of Oxford. The first teaching position he accepted was at the University of California, Berkeley; he would remain at UC Berkeley for the rest of his career. He specialized in spectroscopy, using Fourier-transform infrared spectroscopy to determine the traits of various molecules. He also employed Raman spectroscopy and neutron spectroscopy "to study the rotations and vibrations of molecular hydrogen embedded in various systems".
From 1976 to 2000, he was the editor of the Annual Review of Physical Chemistry. From 1995&ndash;2008, he was the Associate Dean of Undergraduate Affairs. He officially retired from Berkeley in 2003, though continued to teach until shortly before his death.