Herzberg As My Mentor

By Takeshi Oka

Takeshi Oka (Department of Chemistry and Department Astronomy and Astrophysics, the Enrico Fermi Institute, the University of Chicago) worked as a postdoctoral fellow with Harry Kroto at Gerhard Herzberg’s laboratory with the National Research Council of Canada. Oka was a Fellow at JSPS in the University of Tokyo. Afterward, he worked at the Herzberg Institute of Astrophysics and the University of Chicago. His research group’s studies specialized in the field of the quantum mechanics and dynamics of fundamental molecular ions and their behaviour in astronomical objects.

Oka’s studies are concentrated in astrochemistry, an interdisciplinary field unifying astronomy and chemistry. His team discovered long-chain cyanoacetylene molecules HC5N, HC7N and HC9N, and initiated interstellar carbon chain chemistry. This work has been revived recently in the studies of diffuse interstellar bands. In 1980, Oka & his laboratory discovered the infrared spectrum of H+ which is thought to be the starting point for gas phase chemistry in interstellar “molecular clouds.” Following a lengthy search Thomas R. Geballe and Oka spectroscopically detected H+3 in two interstellar clouds. Since then Oka and his colleagues have published numerous papers on their observations of interstellar H+3.

When Herzberg moved from the Yerkes Observatory of the University of Chicago to the NRC in 1948 at the age of 43, he was determined to create a leading group of molecular spectroscopists in Ottawa. He had already been established as a leader of spectroscopy with the publication of Atomic Spectra and Atomic Structure in 1937, Molecular Spectra and Molecular Spectra: vol, I. Diatomic Molecules in 1939, and vol. II. Infrared and Raman Spectra of Polyatomic Molecules in 1945 which, together with vol. III. Electronic Spectra and Electronic Structure of Polyatomic Molecules to be published in 1966 would become the bible for molecular spectroscopists.

Herzberg first asked A. E. Douglas, 32 years old, the brilliant experimental physicist who was his masters graduate student at the University of Saskatchewan, to help him create the group. They hired D. A. Ramsay, H. Lew, C. C. Costain, and B. P. Stoicheff all in their 20’s. They were hired because of their excellence and were given complete freedom for their own research. This independence and freedom were essential for the NRC group to become the mecca of molecular spectroscopists. In the citation for Herzberg’s Nobel Prize, the Nobel committee mentioned “the only institutions which have previously played such a role were the Cavendish Laboratory in Cambridge and Bohr’s Institute in Copenhagen.”

Herzberg himself concentrated on his own research. Having discovered in 1948 at Yerkes the infrared quadrupole spectrum of H2 which became a powerful astrophysical probe, he was at the peak of his career as an experimental physicist. His ambition was to discover the spectrum of CH2 whose search he initiated in 1942. After 17 years he discovered the spectrum with technician J Shoosmith in 1958 using the 3 meter vacuum spectrograph, the third generation of an instrument which he had built earlier in Saskatchewan and in Yerkes. This discovery along with the discovery of the spectrum of CH3 in 1956 were the direct reason for his Nobel Prize in 1971 “for his contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals.” In the memento in honor of Herzberg’s forty six years at the NRC is inscribed “CH2 The simplest Organic Molecule” and a picture of CH2.

After the success of CH2 in 1958 Herzberg and Douglas started the second round of hiring. Unlike the first, the new staffs were selected from among the 5 or so postdoctoral fellows which the group introduced every year. J. W. C. Johns was appointed in 1961 and J. T. Hougen in 1962. Then I was hired in 1965. When Alex Douglas mentioned it to me, I was flabbergasted; the thought had never occurred to me. I was not the only one surprised by the decision. Frank Doren, the machinist for the group whose shop I frequented, told me that all spectroscopy section was surprised. A candid man, Frank added that all were booing the decision. The group at that time was a crucible of young, vigorous spectroscopists. Some of them published many excellent papers on discoveries of important free radical spectra. In contrast I tried a difficult experiment and ended up without any publication. It must have been a big gamble to hire me. It was a gamble on my part also to forgo my position of an assistant at the University of Tokyo and stay in Ottawa. But right from the beginning I felt mutual understanding and trust both with Herzberg and Douglas and I very willingly took the gamble.

In those days more than a half century ago, there were many people who knew Herzberg and genuinely admired him. Sadly most of them have passed away. As one of the very few still left I feel responsible to leave an accurate record of Herzberg. In this project of the national commemoration for the 50th anniversary of Dr. Gerhard Herzberg’s Nobel Prize in Chemistry, three people mentioned “Herzberg was a big advocate for team work”. Nothing is farther from the truth! No original scientist advocates for team work. In an interview with the Winnewissers[i], Herzberg likened his writing of the 3 volumes of books with Wagner’s composing the 3 operas of Der Ring des Nibelungen. For him the scientists’ activities were similar in essence to composing music, painting fine arts, and writing novels. Team work has no place in them.

I think I am the best witness of this.[ii] I was a cocky disciple. I chose Ottawa for my postdoc because I was attracted to Herzberg the person but I had no intention to study free radicals. I was fascinated by the method of double resonance invented by my thesis supervisor Koichi Shimoda, a genius experimental physicist. My first work in Ottawa which led to a Steacie prize was double resonance studies of molecular collisions, which was not even spectroscopy. For me spectroscopy was a tool to do interesting physics. Both Herzberg and Douglas understood this and kept promoting me and supporting my budget even though my work was outside of their primary interest. They kept me completely free. Herzberg’s reluctance to interfere with my research was so strong that he never made a suggestion during my 18 years as his staff.

The crown jewel of Herzberg’s group was the spectrum of H3+ which I observed in 1980. Until I met Herzberg I didn’t even know that such molecule existed. The spectrum was a holy grail of ambitious physicists. Herzberg had been after the spectrum since 1941. I inherited this jewel from him and observed it after 5 years support of Douglas and Herzberg.[iii] [iv]I wish to emphasize here that the observation was possible because Herzberg left me completely free. My paper was published as a single author paper. Surely it was not a team work.

Herzberg was a pure, truly exceptional scientist. According to the list in the biography by Stoicheff[v] Herzberg published 269 papers from 1927 to 1996. The pace of ~ 4 papers per year has not changed throughout his life. More than half of the papers (138) are single author papers; the rest are mostly two author papers (93). He cannot be a big advocate of team work. I learned so much from him and I call him my mentor as in the title of this article. But mentor of what?

My mentor of experimental physics was clearly Koichi Shimoda. My mentor of theoretical physics was the textbooks of Landau and Lifshitsz. What I learned from Herzberg was not technical matter. It was attitude toward science and life. It was huge and I have no hesitation to call him my mentor although I have not published any paper with him.


[ii] Oka, T. Reminiscence of Gerhard Herzberg at N.R.C. in Physics in Canada, 1985, pp 68-74

[iii] Oka, T. A memorial tribute to Gerhard Herzberg, May 11, 1999, pp 19-21

[iv] Herzberg, G. Trans. Roy. Soc. Can. (Ser. IV) Vol XX, 151-178, 1982

[v] Stoicheff, B. Gerhard Herzberg, An Illustrious Life in Science