Ken HedbergIn Memorium
Kenneth W. Hedberg

In the world of gas-phase electron diffraction, an era ended with the passing of Kenneth W. Hedberg. Ken, as he was best known, died in his sleep on 5 January 2019, just four weeks before his 99th birthday. In a scientific career spanning more than 70 years, he was a preeminent figure in gas-phase electron diffraction (GED). At the beginning, he was a pioneer in not only the use of this technique but also in the development of methods to more effectively extract quantitative molecular structure information from the diffraction data. Over a longer period, he developed what has been described as one of the best GED apparatus in the world in his laboratory at Oregon State University in Corvallis, Oregon.

Ken was born on 2 February 1920, in Portland, Oregon, and spent his early years in Portland, Hoquiam (Washington), and Medford (Oregon). He graduated from Oregon State College (now Oregon State University) in 1943. During the war years, he worked at Shell Development Company in California. In 1946 he joined the research team of Linus Pauling and Verner Schomaker at Caltech, and this collaboration led to Ken’s entry into gas-phase electron diffraction, which held his interest for the rest of his life -- a paper on the structure of NiCl2 was accepted by the Journal of Molecular Structure just two weeks before he died. After receiving his Ph.D. at Caltech in 1948, Ken remained at Caltech as a postdoc. His stay there was interrupted during 1952-53 by a year in Oslo, working with professor Otto Bastiansen, another important person in the development of GED. Here he met his future wife and long-term collaborator, Lise Smedvik (now Lise Hedberg).

The electron diffraction apparatus in Oslo, using the sector method, produced data that was superior to that previously available, and to take full advantage of this quality Ken later developed a least-squares technique for extracting molecular parameters from the data. This replaced the previously used “visual” technique, which depended greatly on the user’s intuition, skill, and experience. At first, the least-squares calculations were done on mechanical desk calculators – a tedious and time-consuming process. When digital computers became available Ken and Lise were quick to exploit them, and the least-squares method became the standard method for analyzing GED data.

In late 1953 Ken, with Lise, returned to Caltech where they continued research on GED. Two years later Ken accepted a position in the Chemistry Department at Oregon State University, and early in 1956, the Hedbergs moved to Corvallis. At OSU Ken constructed a state-of-the-art electron diffraction apparatus, which he maintained at the cutting edge throughout his career. Attracted by the quality of this facility (as well as by the welcoming ambiance created by Ken and Lise), visitors came from all over the world to make use of it, some returning several times over the years. In 2000, one visitor described the instrument as “the very best in the world”, and in 2001 another said that “Corvallis is a great place for a person working in the field of electron diffraction”. The visitors’ logbook, covering a period of 40 years, is almost a “Who’s Who” of those interested in small-molecule molecular structure, including more than 75 scientists from 16 different countries

In addition to providing a research home for visitors, Ken, in collaboration with students, postdocs, and Lise, carried out a vigorous research program of his own. He was motivated by Pauling’s dictum that the conformation of a molecule is closely related to its function, and that, therefore, it is essential to know and to understand the conformation. Ken typically chose molecules that would illuminate questions of fundamental interest, with the goal, as he put it, of answering the question of “why are things the way they are?” At the same time, he was well placed to provide structural information when new molecules appeared on the scene, and he was the first to use GED to determine the gas-phase structures of the fullerenes, C60, C70, and C60F48.

Ken Hedberg was a member of the American Chemical Society and a fellow of the American Physical Society, where he served terms as secretary-treasurer, vice-chairman, and chairman for the Division of Chemical Physics. He was a fellow of the American Association for the Advancement of Science, a Norwegian Marshall Plan Fellow in 1982, the Odd Hassel Memorial Lecturer at the University of Oslo in 1984, and the Edward A. Guggenheim Memorial Lecturer at the University of Reading, England in 1994. He received the Sigma Xi Research Award at Oregon State University in 1974 and the O.S.U. Alumni Distinguished Professor Award in 1975. He has been Visiting Professor at the University of Oslo, Norway, at the University of Texas at Austin, and at the University of Reading, England. He was elected foreign member of the Norwegian Academy of Sciences in 1978, of the Royal Norwegian Society of Science and Letters in 1996, and in 1992 he received an honorary doctorate (Dr. Phil) from the University of Trondheim, Norway. In 2005 he was awarded the International Dr. Barbara Mez-Starck Prize (given for outstanding contributions in the field of experimental structural chemistry). In 2016 his contributions to science and to OSU were recognized by his receipt of OSU College of Science Lifetime Achievement in Science Award.

Ken was a man who participated in life to its fullest. In addition to his consuming interest in science, he enjoyed the outdoors, music, good food, good wine, and good company. Ken will be lovingly remembered as a man of extraordinary intelligence, kindness, wit, and joie de vivre who applied his mind and heart fully to what he called in his last days a “good, long life”.

Joseph W. Nibler and T. Darrah Thomas, Oregon State University

Kolbjorn Hagen, Norwegian University of Science and Technology