Mark Johnson, Ph.D.
Mark Johnson is the Arthur T. Kemp Professor in the Department of Chemistry at Yale University. Johnson is known for the development and exploitation of experimental methods that capture and structurally characterize transient chemical species, such as reaction intermediates, using cryogenic ion chemistry in conjunction with multiple resonance laser spectroscopy. Johnson was born and in Oakland, California in 1954 and raised in the San Francisco Bay Area. He graduated from the University of California at Berkeley with a degree in chemistry and from Stanford University in 1983 with a Ph.D. chemistry with Dick Zare. He was a postdoctoral fellow with Carl Lineberger at JILA/University of Colorado, Boulder, from 1983-1985 and joined the Yale faculty in 1985. He has served as Chair of APS Division of Laser Science and the ACS Division of Physical Chemistry, and is presently co-editor of the Annual Review of Physical Chemistry.
Mark Johnson’s laboratory specializes in understanding chemical processes that occur in condensed phases by extracting key species directly from solution, freezing them into well defined geometries and characterizing the potential energy surfaces that govern reactions through precision spectroscopic measurements. This requires design and construction of new types of instrumentation that draw inspiration equally from analytical chemistry and atomic physics. From this effort has evolved a powerful new class of spectrometers that effectively bring an FTIR-like capability to mass spectrometry. With it, he can structurally analyze the wide range of species accessible through atmospheric ionization techniques like electrospray ionization. In essence, he combines multi-dimensional laser spectroscopy with the extreme sensitivity of mass spectrometry to yield a qualitatively new way to follow chemical processes at the molecular level. These methods have provided microscopic pictures of how elementary species like protons and electrons are accommodated by water networks, as well as enable capture key reaction intermediates in both bio-inspired and organometallic catalysis. Although much of his work focuses on the properties of ions, he has also introduced variations that enable composition and size-selective measurements to be carried out on electrically neutral systems, with a notable application to homogeneous water clusters.