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The Joy of Discovery in Surface Chemistry† What an astounding phenomenon! There in the bottom of the test tube the sulfur dioxide gas I had made by a chemical reaction actually did liquify at - 78 °C. I could see it boiling away as I lifted the tube from the cold bath. Thrilled with this, I ran into the garden and showed my mother, who unfortunately sniffed the bubbling liquid and promptly keeled over. Luckily recovery was swift, but I realized my fascination with a boiling liquid in a frosty tube was purely a personal one! I have always been an experimenter even at age 4sstoring concoctions under the kitchen sink, delving into the magic of Porter Chemcraft chemical setssand now at age 12 liquifying sulfur dioxide gas in my own basement laboratory. This was a magnificent laboratory built with the assistance of my father’s ingenuity and my mother’s good wishes! With a second-hand analytical balance, a drying oven powered by light bulbs, a fume hood powered by an electric fan created from an Erector set, and a copy of Treadwell and Hall’s Quantitative Chemical Analysis, I began to explore the world of chemical measurements. Commercially analyzed limestone, coal, and fertilizer samples became my unknowns. Absolutely fascinating was the Kjeldahl analysis for the measurement of protein nitrogen! This basement activity led in the 10th grade to an after-school job with the Voris Laboratory in Hagerstown, Maryland. There for 50 cents an hour I was even paid to do what I loved to doschemical analyses on a variety of commercial products. The bench work was fun and gave me a lot of practical experience, but the more important aspect of this job as it related to my future career was the interaction with the owner, Mr. L. R. Voris. He was an extraordinary personality with the ability to always see a deeper dimension in everything he encountered, and he provided an example of almost unbounded enthusiasm for scientific work that has continued to influence me to this day. In 1952 I entered Juniata College in Huntingdon, PA as a “special” chemistry students“special” being defined as someone who left high school after the 11th grade without a diploma. The personnel and atmosphere at this small liberal arts institution †
Part of the special issue “John T. Yates, Jr. Festschrift”.
played a dominant role in my life. At Juniata, I encountered physical chemistry in the laboratory, learned a little about the theoretical basis of chemistry and learned a bit of physics. I decided at Juniata that physical chemistry was just right for me. Two Juniata professors were responsible for stimulating my interest in physical chemistry. The first professor was R. T. Davis, Jr. who had been one of Paul Emmett’s students. Dr. Davis was engaged in BET studies of high area solids in the basement of the old chemistry building, and while I did not assist him, I did observe. This was my introduction into surface chemistry, and from that moment on, I have never lost my fascination for atoms and molecules on surfaces. I was impressed by the complex glass BET apparatus with its myriad of stopcocks, expansion bulbs and mercury manometers. For me it was fascinating that some aspects of the molecular behavior of adsorbed gas molecules could be visualized just from knowing about PV ) nRT, and using this relationship to determine the gas coverage versus pressure at equilibrium. The second Juniata professor was Dr. B. E. Blaisdell, an extraordinary research chemist, who had been a student of J. A. Beattie at MIT. He taught me how to measure and evaluate secondorder issues affecting physical chemical measurements. In Professor Blaisdell’s physical chemistry laboratory course, one could obtain an extra 100% by significantly extending a traditional experiment beyond the scope of the text and this provided a weekly challenge. In my courses and research with Dr. Blaisdell, I learned to use and to appreciate the beauty of things like the least-squares method for fitting data and also the art of glass blowingsa necessary skill for the construction of our sealed vacuum distillation apparatus for producing oxygen-free solvents for photochemistry experiments on the fading of dissolved dyes. At Juniata I also encountered Kerin Narbut, a chemistry student. We were married when she finished her B.S. degree in 1958. I heard Linus Pauling later say that finding a good partner in life was the most important thing one could do and this has certainly been true. During our 42 years of marriage, Kerin has
10.1021/jp003332z CCC: $20.00 © 2001 American Chemical Society Published on Web 02/24/2001
3680 J. Phys. Chem. B, Vol. 105, No. 18, 2001 supplied an essential loving and understanding environment for my endeavors and has actively participated in interactions with students and colleagues. Teaching college chemistry, which was my professional goal at the time, meant graduate school, and MIT came into focus upon reading the work of Professor Carl Garland. His impressive use of infrared spectroscopy for the study of chemisorbed molecules on catalysts at MIT shouted “novelty” for me. Here was something far beyond PV ) nRT for understanding adsorbed species!! So the Fall of 1956 found me under Carl’s tutelage and in the atmosphere provided by a major research institution in the cultural and geographical setting of Boston. Work with Carl was inspirational. I learned as a student to improvise to get things done. The research that was to become my thesis and then my first publications“The Adsorption of CO on Ni” in the Journal of Physical Chemistry in 1961swas done on a borrowed Perkin-Elmer model 12 prism instrument modified with a grating in series with the prism and a very slow Brown strip chart recorder for recording the infrared data. The spectrometer was located in a separate vibration-isolated building off the basement corridor of the chemistry buildingsthe MIT spectroscopy laboratoryswhere Al Danti, Rod McDowell, Jim Durig and Walt Laffertysall destined to become leading molecular spectroscopistssworked with Professor Dick Lord. Since one of my goals was to teach, I sampled exemplary lecturing at MIT. Carl’s thoughtful lectures resulted in my love for statistical mechanics. In an undergraduate lecture, Professor Walter Stockmayer wrote one formula, S ) k ln W, on the board and spent an entire hour in fascinating discussion of its implications. Professor John Slater, in Physics, lectured flawlessly on quantum mechanics without lecture notes and each day he ended at the bottom right-hand corner of the eighth and last blackboard at the moment the bell rang. May of 1960 saw the end of my MIT experience with the granting of my Ph.D. I had made my entry into research on the molecular behavior of adsorbed moleculessa topic which has been a continuous driving force in my work to the presents and I was on my way to continue that work and to teach at Antioch College in Yellow Springs, OH. There I enjoyed teaching and the interaction with many excellent students, several who went on to become distinguished academic research chemists. However, I discovered at Antioch, a personal need to have greater research opportunities and so in 1963, Kerin and I went to Washington, DC, where I had won an NRC postdoctoral fellowship at the National Bureau of Standards (NBS, now called NIST). During the first year at the National Bureau of Standards I worked with Dr. Milton Scheer and Dr. Ralph Klein in the Surface Chemistry Section. In my second year, I met and joined with Dr. Theodore Madey, also an NRC Fellow, and our happy collaboration of 19 years is a well-known example of a longlasting professional relationship in the field of surface science. Ted is a physicist trained at Notre Dame. He taught me some surface physics while I taught him some surface chemistry. Together we explored the properties of simple adsorbed molecules on polycrystalline tungsten filaments using glass ultrahigh vacuum systems, and then extended our work to the study of adsorption on single crystal surfaces. In about 1967, we became interested in the electronic excitation of adsorbed molecules, based on the earlier work of Paul Redhead at the NRC in Canada and on the papers of Bob Gomer and Dietrich Menzel at Chicago. These workers had independently shown that electron stimulated desorption (ESD) took place. They laid the basic foundation for thinking about how ESD might occur.
In 1974, Ted and I, working with a visiting postdoctoral, Jerzy Czyzewski, discovered that ESD produced rather sharp beams of desorbing ions whose ejection direction was correlated closely with the direction of the chemical bond in the surface species adsorbed on the crystal surface. A new phenomenon and measurement technique, ESDIAD (electron stimulated desorption ion angular distribution), was born and subsequently employed for structural studies of a number of simple adsorbate molecules. The discovery of the ESDIAD effect was a highpoint for the three of us, but our first paper was initially rejected by Physical ReView Letters because they had a rule at the time limiting acronyms to 5 or less letters. We removed the acronym and the paper was then accepted. Two enriching sabbatical experiences occurred while at NBS. The first was in 1971 with Professor David King at the University of East Anglia in Norwich, England. Here we carried out ESD experiments and some of the first reflection infrared spectroscopy measurements on adsorbed molecules deposited on initially clean planar metal surfaces. We used an ancient Grubb-Parsons IR spectrometer and averaged and averaged to see the signal from adsorbed CO. I remember making measurements only at night while standing dead still in the laboratory to prevent disturbing this venerable instrument. The stimulation of working with Dave King was a formative experience for me, and I learned from him how relatively simple experimental methods, coupled with great insight, could lead to profound understanding about surface phenomena. My second sabbatical from NBS was spent at Caltech in 1977 in the wonderful surface science laboratory of Professor Henry Weinberg. Henry possesses technical and intellectual skills of the highest order and I will never forget this inspirational experience. His office had a big sign over the entrance saying “Frontiers of Surface Science,” and the sign spoke the truth. There I worked closely with Pat Thiel and for the first time I learned how exciting and productive it can be to work with such a well-trained, skilled, and energetic and hard-working student. These two sabbatical experiences implanted the idea of joining the faculty of a university to work with research students. In 1982 I took the leap by joining the Department of Chemistry at the University of Pittsburgh and established the University of Pittsburgh’s Surface Science Center. Two faculty members, Professor Dave Hercules and I formed the leadership for the Center. We enjoyed building separate programs focused on analytical and physical aspects of surface science. Five students and several postdoctorals joined me in the first year and I built up a group that eventually grew to be 22 in number at its maximum. In the intervening 18 years my group has worked in a number of very different areas of surface chemistry, including surface photochemistry, kinetics, heterogeneous catalysis, STM and other studies of semiconductor surfaces, ESDIAD, and infrared and HREEL spectroscopies of surface species. Our work has extended into materials science issues involving metals, semiconductors and insulators, the scientific understanding of corrosion passivation, and the use of surface phenomena for environmental remediation. The extension of our interests into many areas where surface processes dominate has reflected the maturation of the field of surface chemistry and its extension to more complex issues of technological importance. While surface chemistry has evolved toward more and more complex chemical issues, I firmly believe that the application of refined physical methods to fundamental questions involving model experimental systems still forms a significant basis for continued advancement in this field. I hope that we will be able to continue to contribute to these fundamental issues in the future. For
J. Phys. Chem. B, Vol. 105, No. 18, 2001 3681 example, just now, in collaboration with Professor Richard Smalley, at Rice University, we happen to be interested in the fundamental surface chemistry of carbon nanotubes. This has led to the establishment of a new nanoscience branch of the Surface Science Center headed by Professor Joachim Ahner, a talented physicist who has been centrally important in developing our capabilities at Pittsburgh. I titled this "The Joy of Discovery in Surface Chemistry”. The joy of discovering a new phenomenon is the immediate reward of research. The longer term reward however is the personal molding process which comes about for all participants during the process of discovery. I believe that human personality, combined, of course with the proper technical training, is
the dominant human force which shapes scientific discovery. Personality governs how we think about the world and supplies the motivation and perseverance as we wrestle with issues leading to a deeper understanding of Nature. I have worked joyfully with more than 200 colleagues from all over the world. Their contributions have been immense, and I have learned much from each one. As we move into the first decades of the 21st century, I hope to be able to continue cooperative work with many others and to contribute to science enthusiastically. I wish to thank Professors Kenneth Jordan and Eric Borguet of the University of Pittsburgh for the idea of producing this special edition of the Journal of Physical Chemistry, and Professor Mostafa El-Sayed for his blessing on the enterprise.
John T. Yates, Jr.
