I was born in San Jose, California on June 18, 1932, the first of six children of Robert and Dorothy Herschbach. My father was then a building contractor and later a rabbit breeder. His family had lived in this part of California for three generations; although our surname comes from a pair of villages in the Rhine Valley, most of his immediate ancestors were of English or Irish origin. My mother's family had moved to San Jose from Illinois when she was a young girl; most of her known ancestors were of German, Dutch, or French origin. In my boyhood we lived in what was then a rural area of fruit orchards, only a few miles outside San Jose. For years I milked a cow, fed the pigs and chickens, and during summers picked prunes, apricots, and walnuts. From an early age I loved to read but was also very involved in outdoor activities, scouting, and sports. My interest in science was excited at age nine by an article on astronomy in National Geographic; the author was Donald Menzel of the Harvard Observatory. For the next few years, I regularly made star maps and snuck out at night to make observations from a locust tree in our back yard. When I attended Campbell High School, I took all the science and mathematics courses offered. Chemistry I found at first puzzling and then most intriguing, thanks to John Meischke, a superb teacher. At the time, I was at least as interested in football and other sports; perhaps that presaged my later pursuit of molecular collisions. Like most of my classmates, I did not expect to attend college; none of my known relatives had graduated from a university. However, my teachers and coaches presumed I would go. Indeed, I received offers of football scholarships from some universities to which I had not even applied for admission.

I entered Stanford University in 1950 and found a new world with vastly broader intellectual horizons than I'd imagined. Although I gladly played freshman football, I had turned down an athletic scholarship in favor of an academic one. This permitted me to give up varsity football after spring practice, in reaction to a dictum by the head coach that we not take any lab courses during the season. By then the lab and library already were for me much the more exciting playground. My chief mentor at Stanford was Harold Johnston, who imbued me with his passion for chemical kinetics. Many other subjects and professors were also compelling and I took up to ten courses a term. Mathematics was especially appealing; I so admired the teaching of Harold Bacon, George Polya, Gabor Szego, and Bob Weinstock that I simply took all the courses they gave. I received the B.S. in mathematics in 1954 and the M.S. in chemistry in 1955. My Master's thesis, done under the direction of Harold Johnston, was titled: "Theoretical Pre-exponential Factors for Bimolecular Reactions." It employed the transition-state theory of Henry Eyring and Michael Polanyi and treated the proportionality factor in the most venerable formula of chemical kinetics, the Arrhenius equation. My graduate study continued at Harvard, where again I found an exhilerating academic environment. I received the A.M. in Physics in 1956 and the Ph.D. in Chemical Physics in 1958.

My Doctoral Thesis, done under E. Bright Wilson, Jr., was titled: "Internal Rotation and Microwave Spectroscopy". This presented theoretical calculations and experiments dealing with hindered internal rotation of methyl groups. The height of the hindering barrier could be accurately determined because the observed spectra were very sensitive to tunneling between equivalent potential mimima. Much that shaped my later research I learned from Bright Wilson and other faculty, especially George Kistiakowsky and Bill Klemperer, or from fellow students, especially Jerry Swalen, Victor Laurie and Larry Krisher.

My thesis work also benefited from visits of several months to take spectra at the National Research Council in Ottawa and to compute Mathieu functions at Los Alamos National Laboratory. During 1957-1959, while a Junior Fellow in the Society of Fellows at Harvard, I developed plans for molecular beam studies of elementary chemical reactions. This work was launched at the University of California at Berkeley, where I was appointed an Assistant Professor of Chemistry in 1959 and became an Associate Professor in 1961. The chief experiments dealt with reactions of alkali atoms with alkyl iodides, systems studied forty years before by Michael Polanyi. Rather simple apparatus sufficed to attain single-collision conditions and revealed that the product molecules emerged with a preferred range of recoil angle and translational energy. The possibility of resolving such features of reaction dynamics encouraged other workers pursuing kindred experiments and fostered an outburst of new theory.

My early work thus interacted particularly with that of Richard Bernstein, Sheldon Datz, Ned Greene, John Polanyi, John Ross, and Peter Toennies. This new field developed rapidly after I returned to Harvard in 1963 as Professor of Chemistry. We studied a wide range of alkali reactions and found several prototype modes of reaction dynamics which could be correlated with the electronic structure of the target molecule.

Processes involving abrupt, impulsive bond exchange or formation of a persistent complex comprise the two major categories. In 1967 Yuan Lee joined our group as a postdoctoral fellow and led the construction of a "supermachine". This employed greatly augmented differential pumping, sophisticated mass spectroscopy using ion counting techniques adapted from nuclear physics, and supersonic beam sources advocated by enterprising chemical engineers, especially John Fenn and Jim Anderson. The new machine greatly extended the scope of crossed-beam experiments, taking us "beyond the alkali age". In particular, we were then able to study the same reactions elucidated by John Polanyi with his complementary method of infrared chemiluminescence. This much enhanced the interpretation of reaction dynamics in terms of electronic structure. The most representative descriptions of the work recognized by the Nobel Prize probably appeared in: Adv. Chem. Phys. 10, 319-393 (1966). Disc. Faraday Soc. 44, 108-122 (1967). J. Chem. Phys. 56, 769-788 (1972). Faraday Disc. Chem. Soc. 55, 233-251 (1973). Pure and Applied Chem. 47, 61-73 (1976). Mol. Phys. 35, 541-573 (1978). J. Phys. Chem. 87, 2781-2786 (1983). In current research we are developing a method for simultaneous measurement of three or four vector properties of reactive collisions, such as reactant or product relative velocities or rotational angular momenta.

Theory has shown that data on correlations among these vectors can undo much of the averaging over initial molecular orientations and impact parameters and thereby reveal more incisive information about reaction dynamics. Other studies deal with processes akin to liquid-phase reactions by solvating reactant molecules during a supersonic expansion. We are also examining bulk liquid interactions by means of vibrational frequency shifts induced by high pressure; this offers a way to determine solute-solvent intermolecular forces. In addition to theoretical studies related to these experiments, we are pursuing a new approach to electronic structure calculations which exploits exact solutions obtainable in the limit of one- and infintie-dimension. For two-electron systems this has given high accuracy for the electron correlation energy with far less effort than conventional methods.

Other biographical items pertaining to Harvard include my appointment in 1976 as Frank B. Baird, Jr. Professor of Science; service as Chairman of the Chemical Physics program (1964-1977) and the Chemistry Department (1977-1980), as a member of the Faculty Council (1980-1983), and as Co Master with my wife of Currier House (1981-1986). At Currier we were in effect reincarnated as undergraduates to preside over an extremely lively community of 400 students and tutors. Typical of many memorable episodes was the night we were summoned to a student's room to meet a seal in the bathtub. My teaching includes graduate courses in quantum mechanics, chemical kinetics, molecular spectroscopy, and collision theory. In recent years I have given undergraduate courses in physical chemistry and especially general chemistry for freshmen, my most challenging assignment.

Away from Harvard, I have been a Visiting Professor at Gottingen University in 1963, a Guggenheim Fellow at Freiburg University in 1968, a Visiting Fellow of the Joins Institute of Laboratory Astrophysics in 1969, and a Sherman Fairchild Scholar at the California Institute of Technology in 1976. I also serve as a consultant to Aerodyne Corporation, the Fluorocarbon Research Panel, and Los Alamos National Laboratory. I was appointed an Exxon Faculty Fellow in 1981 and visit regularly the Corporate Research Laboratory in New Jersey to participate in projects there.

I have also served since 1980 as an Associate Editor of the Journal of Physical Chemistry. Other honors include election to the American Academy of Arts and Sciences in 1964 and to the National Academy of Sciences in 1967; the Pure Chemistry Prize of the American Chemical Society in 1965, the Linus Pauling Medal in 1978, the Michael Polanyi Medal in 1981, and the Irving Langmuir Prize in Chemical Physics in 1983. The University of Toronto bestowed in 1977 the D. Sc., honoris causa. Chemistry also brought my wife Georgene Botyos to Harvard as an organic graduate student. We were married in 1964 and our daughters Lisa and Brenda arrived as harbingers before she received her Ph.D. in 1968.

Georgene is now Assistant Dean of Harvard College, a multifaceted position that often requires delicate personal chemistry. Lisa is now a junior in humanities at Stanford, this year enjoying the overseas option at Oxford. Brenda is a junior in chemistry at Harvard, already pursuing research. Our home is in Lincoln, Massachusetts.