Obituary of Gert Ehrlich (1926-2012)

Gert Ehrlich, who made important contributions to surface science, especially in the area of atomic interactions on solid surfaces, died of leukemia on August 10, 2012. Now referred to by the popular term of Nano Science and Technology, his work in that general field preceded this name by over 40 years and has contributed significantly to it. For the last 44 years of his life, up to within 5 weeks of his death, he worked tirelessly as a Teaching and Research Professor in the Department of Materials Science at the University of Illinois. He is a coauthor of over 200 scientific articles as well as of the book, Surface Diffusion: Metals, Metal Atoms, and Clusters.

Gert was born on June 22, 1926, in Vienna, Austria. His first notable life experience occurred during that tumultuous time when Germany annexed Austria, the “Anschluss” of 1938. While his mother was Catholic, his father was Jewish. Consequently, Gert and his father were detained for questioning but luckily released. The family responded to this “wake up call” with the father’s immediate departure to the United States. Gert and his sister, Dorothy, were sent to the United States, unescorted, on the T.S.S. Veendam, arriving in New York in May 1939. Although they were alone during the entire journey, what might have been a harrowing voyage actually turned into a grand adventure for Gert. He investigated all aspects of the ship’s operation and explored the ship from top to bottom. Gert’s mother managed to join the rest of the family several months later.

In 1944 Gert enrolled in Columbia College. Even though his college years were interrupted by service in the United States Army from 1945 to 1947, he graduated from Columbia University with honors in Chemistry in 1948. He then obtained his PhD in Chemistry from Harvard University in 1952. His advisor was Prof. Paul Doty and his thesis title was “Studies on Synthetic Polyampholytes”. Thereafter, Gert remained at Harvard for a year as a National Institutes of Health Fellow. In the following year he served as a Research Associate in the Department of Physics at the University of Michigan, Ann Arbor, working with Prof. Gordon Sutherland on infrared spectroscopy of macromolecules.

In 1953 he accepted a full time research appointment at the General Electric Research Laboratory in Schenectady, NY. There he met and married his lifetime spouse, Anne Vogdes Alger. His research at General Electric was to develop a better understanding of the kinetics of gas-solid interactions. He pioneered the development of temperature-programmed desorption – flash desorption – techniques into a quantitative method for kinetic studies at the gas solid interface. He demonstrated the importance of distinct binding sites in chemisorption phenomena. He then became interested in the underlying atomic details of these macroscopic observations, using the field ion microscope that had recently been invented by Erwin W. Müller. This microscope revealed for the first time atomic resolution on a crystal surface. He made unique chemisorption studies on single crystal surfaces, followed by the first quantitative observations of individual atoms diffusing on a metal surface. The corresponding publication on “Atomic View of Surface Self-Diffusion – Tungsten on Tungsten” (J. Chem. Phys. 44, 1039, 1966) has been cited over 1000 times. For the first time, real space images of individual atoms moving on a surface were shown in this article that appeared almost thirty years before such studies became common in nanotechnology.

In 1968 Gert Ehrlich accepted a Professorship at the University of Illinois where – with the vital assistance of a small group of graduate and postdoctoral students – he continued and expanded his atomic-scale research. The group’s most notable work during that time includes the first direct observation, using an atom probe field ion microscope, of an adatom exchange mechanism in diffusion phenomena. Numerous details of the surface diffusion process were observed and characterized, including the direct observation of interior step edge barriers (for example, on Ir(111) and Pt(111) surfaces) and also the existence of a reflective barrier on some plane edges including W(110). His group reported that there exist two types of adsorption sites on some surfaces (including Ir(111) and Pt(111) planes) and – to further complicate the atomic diffusion process -- that there is adatom/vacancy interaction as well. His group also reported experimental evidence of long jumps (in contrast with multiple single jumps) in one-dimensional and two-dimensional surface diffusion and the temperature dependence of these jumps. The group also investigated adatom cluster motion, incorporating various Monte Carlo and molecular dynamic simulations to better understand the dynamics of their observations.

After the invention of the Scanning Tunneling Microscope the group’s diffusion studies were expanded to larger and more complex surfaces, including the motion of gold adatom clusters on the Au(100)hex reconstructed surface. In summary, Gert and his group developed the apparently hopelessly complicated subject of surface diffusion on the atomic scale into a more understandable and explainable one.

Gert was awarded several honors. Among these are the Welch award from the American Vacuum Society in 1979, “for contributions to our understanding of the microscopic force laws by which atoms residing on solid surfaces interact with the substrate and each other”, and the Kendall Award from the American Chemical Society in 1982 “for his fundamental work on atomic and molecular events on solid surfaces, including diffusion of individual atoms, bonding and clustering of adsorbed atoms and molecular disassociation on metal surfaces”. He was a Guggenheim Fellow, Division of Applied Sciences, at Harvard in 1984-85 and was elected to the National Academy of Scientists in 1986. He was University of Illinois Scholar, 1987-1990, and in 1992 he received a research award from the German Alexander von Humboldt Foundation that he spent at the Fritz-Haber-Institute in Berlin. There he worked on boundary layer chemistry and interfacial chemistry with Gerhard Ertl and with Jochen H. Block. He was a member of the American Chemical Society, the American Vacuum Society, was actively involved in affairs of the Field Emission Symposium and also the Physical Electronics Conference and International Workshop on Surface Physics.

Gert was extremely careful and paid extraordinary attention to detail in his research. The experimental conditions for his studies were equally extraordinary with the highest achievable ultra high vacuum, and precise timing and temperature controls. His graduate and postdoctoral students followed the same rigorous rules of experimentation and are all the better for it. Even in the early days Gert was merciless in the proper statistical analysis of data – no small task in the early slide ruler days when access to a computer meant a time sharing connection on a teletype at 10 characters per second.

Perhaps Gert’s most endearing characteristic was his concern for students. His door was always open for questions and advice, although usually a question was answered with another question to better challenge the student. When not in the lab, he could easily be found: as he wandered the halls he would produce a low enigmatic warbling whistle, usually his unique rendering of an aria from classical opera. He was particularly concerned about the transfer of knowledge among students and established a mentoring system that was especially useful for teaching the necessary know-how and unpublished techniques to incoming students.

Gert Ehrlich was a curious scientist, and his precise work on the behavior of atoms on surfaces laid one of the foundations for modern nanoscience and technology. He also was an excellent teacher, compulsively preparing every lecture, no matter how many times he had previously taught that material. Upon receiving news about the success of a student or former student, he would sport a generous grin and his eyes would sparkle.

Grazyna Antczak

Robert S. Chambers

Armin Gölzhäuser