HERZBERG, GERHARD

(b. Hamburg, Germany, 25 December 1904; d. Ottawa, Ontario, Canada, 3 March 1999), spectroscopy, chemistry, physics, astrophysics.

Herzberg was a seminal and prolific spectroscopist active for over sixty years in Germany, the United States, and most importantly, in Canada. His career was dedicated to the elucidation of molecular spectra and structure, focusing on their experimental observation, correlation with theoretical calculations of molecular structure, and identification of molecular species, particularly in astronomical contexts. This lifelong pursuit led to a series of canonical texts, the Nobel Prize in Chemistry in 1971, the mentoring of a generation of junior colleagues, and a significant role in the administration and promotion of Canadian science.

Early Life and Career . Herzberg was one of two sons born to a middle-class Lutheran family. He began his education in 1911 in Hamburg, Germany, first at the Vorschule on Hegenstrasse and, from 1915, as a scholarship student at the Realgymnasium of the Johanneum. There he developed a strong interest in the sciences—particularly astronomy and atomic physics—and enjoyed languages and philosophy.

In 1924, having graduated with the Abitur (needed for university admission) and a high standing in his class, Herzberg began studies at the Technische Hochschule, Darmstadt (THD), with the help of an industrial scholarship and, two years later, with a federal scholarship, graduating at the top of his class with a Diplom Ingenieur degree in 1927. The following year he gained the Doktor Ingenieur degree under Professor Hans Rau, director of the Physics Institute.

Reading, while an undergraduate, one of Erwin Schrödinger’s papers, “Quantization as an Eigenvalue Problem,” Herzberg’s interest in atomic structure was piqued. His own first three papers, dealing with spectra of hydrogen, were published the year of his graduation. The following year, 1928, was the beginning of a prolific scientific period: he published nine more papers. Herzberg’s dissertation for his Doktor Ingenieur degree concerned the spectra of the N₂ molecule and N₂⁺ion. This early work on molecular spectroscopy and especially radicals such as H₃ were to be templates for the research over his subsequent career.

The duration of Herzberg’s education had been insecure, not least because of the death of his father in 1915 and the emigration of his mother to America in 1922 during the period of rampant inflation in the postwar German economy. Even after his completion of degrees at the THD, Herzberg found that his income remained precarious and that his social class restricted his opportunities for a stable academic career. A series of short but significant posts followed.

In 1928, Herzberg accepted a one-year position as a postdoctoral fellow at the University of Göttingen, working on theoretical problems in the Institute of Theoretical Physics directed by Max Born, and on an experimental investigation of far-ultraviolet molecular absorption spectra at the Second Institute of Experimental Physics of James Franck. This coupling of theoretical and experimental experience, combined with interactions with German physicists and mathematicians actively developing atomic theory and quantum mechanics, provided Herzberg with a solid footing in this rapidly evolving field. Collaborating with Walter H. Heitler at Göttingen on an analysis of the rotational Raman spectrum of N₂, and later contributing to the theory of molecular orbitals originated by Friedrich Hund, Herzberg came to the attention of John E. Lennard-Jones of the University of Bristol, who offered him a research fellowship there.

Herzberg took up this one-year post at the H. H. Wills Physics Laboratory in Bristol, England, in September 1929, and three months later he married Luise Oettinger, another spectroscopist whom he had met at Franck’s institute in Nürnberg. Both returned to Bristol and Herzberg acquired and studied (sometimes with the help of Luise) the spectra of molecules such as P₂, C₂ H₂, and CH₂0 and deepened his understanding of predissociation (an alteration of a molecule in an excited state without the emission or absorption of radiation).

Having completed his habilitation (a postdoctoral qualification in the German academic system that grants access to professorial posts) with a paper on the theory of molecular orbitals, Herzberg returned to Germany in November 1930 to a post as privatdozent (lecturer) at the THD, working from 1931 as an assistant to Professor Hans Rau. As privatdozent, he was able to begin a research program with postdoctoral fellows and the doctoral students he supervised. His work included the use of infrared, visible, and ultraviolet spectrographs to study the spectra of polyatomic molecules, and as at Göttingen, he met and worked with a string of prominent German physicists.

Nevertheless, Herzberg’s career remained unsettled. His post as privatdozent did not include remuneration, so he derived his income from special fee-paying lectures, a stipend from the Emergency Association of German Science, and support from Luise’s father during his first year; as assistant to Rau, he was later to gain a small stipend. The instability was further constrained by the rise of the National Socialist German Workers’ (Nazi) Party. Although not of Jewish background, his surname was commonly misidentified as Jewish. After Adolf Hitler’s ascension as chancellor in January 1933, anti-Semitic and anti-Communist tension rapidly rose in Darmstadt. Moreover, Herzberg’s wife was Jewish, and university officials gradually implemented a policy of barring suspect academics from university research and academic livelihoods. Herzberg felt compelled in May to post a public notice of his Aryan descent, while recognizing that the sentiments of the majority of THD students effectively blocked any hope of a permanent post at Darmstadt. With the departure that year of Franck and Born and most of their Göttingen assistants with whom Herzberg had collaborated, the fleeing of his best doctoral student, Stephan Gradstein, and the news in April 1934 that, owing to his wife’s ancestry, he would no longer be permitted to teach, a future in Germany no longer appeared viable. Rau’s support of Herzberg’s strong spectroscopic research program could provide only a temporary extension as assistant until October 1935.

Reestablishment in Canada . Some two years, then, after many of his colleagues had begun to leave Germany and its rising oppression, Herzberg began more seriously to seek posts in other countries in 1935. Given the difficult economic climate and the earlier exodus of other German academics, there were few positions available, and Herzberg found his applications rejected repeatedly. His eventual success in finding a post resulted from his collaboration some two years earlier with a Canadian physicist, John W. T. Spinks of the University of Saskatchewan in Saskatoon, Canada, who had spent a year in Rau’s lab at Darmstadt. In mid-1935, Spinks was able to arrange a guest professorship at the University of Saskatchewan, supported by a two-year fellowship from the Carnegie Corporation in New York.

Although Saskatoon, located midcontinent in the Canadian prairies, had only a small Physics Department and no suitable research facilities, Herzberg initially seemed to have favored the temporary post as a step toward more appealing possibilities in America. But despite his professional concerns, along with the Great Depression and consequent hesitancy of Canadian immigration officials to accept a permanent immigrant, Herzberg’s post as professor of physics was confirmed in 1936. With the prospect of permanence, the Herzbergs had a son and daughter within two years, rapidly adapting to what was an isolated but welcoming small Canadian city, developing an active social life, and adapting to the extreme climate. Over a period of ten years, Herzberg completed two much-praised books, taught numerous undergraduate and ten master's-level graduate students, and established a competent spectroscopy laboratory.

During World War II, however, opportunities for research were limited; Herzberg found himself excluded from some applied research by his national background but eventually contributed to munitions research via investigations of the spectra of explosives. At the close of the war, Herzberg traced links with colleagues and family that had remained in Germany. He did not visit his native country until 1950 and, noting then the gulf between the postwar cultures there and in his adopted home, chose not to renew some acquaintances (whom he judged to have accommodated too readily to Nazi policies) while actively supporting others with food parcels and other aid.

At Yerkes Observatory . Herzberg took advantage of the opportunity of lowered postwar borders to move from Saskatoon in 1945 to a considerably more isolated community in America: the Yerkes Observatory of the University of Chicago, located in the small town of Williams Bay, Wisconsin. He had been introduced to this community of astronomers during a 1938 conference there on the molecular structure of celestial objects, and had been approached about joining the observatory by its director, Otto Struve, in 1943.

The postwar Yerkes Observatory had a large and changing international community of permanent and visiting research staff and graduate students. Productive research—both observational and theoretical—on planets, stars, and interstellar matter was actively pursued, and the staff was relatively unencumbered by teaching responsibilities. At Yerkes, Herzberg supervised two graduate students and two postdoctoral fellows, all of whom went on to successful careers in spectroscopy. With his small research group, which included Luise, Herzberg recorded molecular spectra of CO₂ and CH₄, which also had been observed on Venus and Jupiter, respectively, and thereby determined the gas pressures and depths of planetary atmospheres. Study of the O₂ spectrum proved valuable for upper atmospheric physics, and his detection of the normally rare infrared spectrum of H₂ in the laboratory later allowed astronomers to confirm the existence of hydrogen in the atmospheres of the outer planets.

While Yerkes offered much greater scope for research than did the University of Saskatchewan—in the form of better facilities and equipment, an opportunity to reorient his work toward astrophysics (which had interested him from boyhood), and potential scientific interaction with more colleagues—the new post was in some respects a step downward. Herzberg was not initially offered a full professorship, and interdepartmental rivalries at Chicago and Yerkes soured the atmosphere. Against all expectations, Herzberg—unlike some of his colleagues—did not obtain a research grant from the new Office of Naval Research in 1946. Adding to the Herzbergs’ ill ease was the rising rhetoric of anti-Communist sentiment, which suggested parallels with the prewar Germany they had left. In spite of the professional and social drawbacks there, the Herzbergs made close friendships in Williams Bay, notably with the Indian theoretical physicist, Subrahmanyan Chandrasekhar, and his wife.

The National Research Council . When Herzberg was offered a more senior Canadian post in 1948 as principal research officer at the National Research Council of Canada (NRCC) in Ottawa, he quickly accepted. He was to remain at the NRCC for the remaining forty-six years of his career. As he had done at Darmstadt, Saskatoon, and Williams Bay, Herzberg established a spectroscopy laboratory in Ottawa, but this time with considerably more ample funding, facilities, staffing, and opportunities for collaboration. The NRCC supported an active program of postdoctoral fellowships and, situated in Canada’s capital city, it was also culturally rich and well placed for international visitors.

Herzberg’s prolific research program was tempered only to a degree by increasing administrative work: from 1949, he headed the NRCC Division of Physics for six years, and then its Division of Pure Physics for a further fourteen years after the section was subdivided into applied and pure branches. A regime of long days and routine weekend work extended his research output and, by example, that of his group.

Herzberg’s scientific research was characterized by a dogged concentration on molecular spectra and on the nurturing of training and collaborations with junior colleagues. Modeling his attentive and supportive supervisory style on that of his own mentor, Hans Rau, Herzberg developed some prominent students. In Saskatoon in 1941, for example, he observed the spectrum of CH⁺ with his master’s student, Alex E. Douglas, and confirmed its presence in interstellar space. Douglas was the first and crucial coworker hired by Herzberg to plan and work in his new Spectroscopy Laboratory in Ottawa—a collaboration that continued for the rest of Herzberg’s career. Douglas was Herzberg’s successor as director of the Physics Division of the NRCC.

The CH⁺ spectrum was emblematic of Herzberg’s new findings throughout his career. The identification of unknown species in laboratory or astronomical spectra became the trademark of his research group. In 1948, he observed the quadrupole spectrum of the molecular hydrogen; in 1956, the spectrum of CH₃, the free methyl radical; and, three years later, CH₂, the free methylene radical. This productivity continued over the next twenty years and beyond. In 1974, Herzberg and Hin Lew identified the spectrum of the H₂ O⁺ ion in the comet Kohoutek, confirming that ice was a significant component in its nucleus, and five years later the team observed the rare spectrum of triatomic hydrogen, H₃. In recognition of his research group’s particular competence in such domains, Canada’s new Herzberg Institute of Astrophysics, which included numerous laboratories and optical and radio observatories, was named after him in 1975.

Books and Recognition . Herzberg had begun his first book, Atomspektren und Atomstruktur, while at the University of Göttingen in response to student requests for an introductory text. Published in Germany in 1936, it was translated into English by Spinks as Atomic Spectra and Atomic Structure when Herzberg joined him in Saskatoon, and was published in 1937 by Prentice-Hall. Beginning as a 160-page text in German, it was expanded some twenty times in length in six volumes written over four decades. Herzberg’s Spectra of Diatomic Molecules, the first volume of his Molecular Spectra and Molecular Structure series, was published in both German and English in 1939, and in 1945 the second volume, Infrared and Raman Spectra of Polyatomic Molecules, was published. The third volume, Electronic Spectra and Electronic Structure of Polyatomic Molecules, appeared in 1966, and a final volume, The Spectra and Structures of Simple Free Radicals—simple free radicals being chemically unstable and transient molecules in the gas phase—was published in 1971.

These lucid and popular books became standards of the discipline. Combined with some 250 papers over his career and the research of the coworkers that he led, Herzberg had a growing impact on the field of molecular spectroscopy, particularly at the NRCC. But external recognition came even sooner. As early as 1939, Herzberg had been admitted as a Fellow of the Royal Society of Canada and, in 1951, to the Royal Society of London. Acknowledged early not merely as a strong individual researcher but as a builder of research culture in Canada, he was director of the Canadian Association of Physicists in 1956–1957 and president of the Royal Society of Canada in 1966–1967. A string of honors followed up to 1970: honorary membership or fellowship of a dozen scientific societies; medals from some eleven scientific societies or organizations; and twenty-eight honorary degrees.

The defining honor was the Nobel Prize in Chemistry, which Herzberg won in 1971, just months after the death of his wife, Luise. The prize cited his “contributions to the knowledge of electronic structure and geometry of molecules, particularly free radicals,” probably the most significant of which were CH₂ and CH₃, the basis of organic chemistry and later observed in interstellar and planetary spectra. The prize, however, recognized an entire lifetime of work in these areas, and his Ottawa laboratory as the center for such research, noting that it played an unusually central role in its field, similar to that of the Cavendish Laboratory in Cambridge, England, and Niels Bohr’s institute in Copenhagen. Herzberg’s studies of diatomic molecules such as H₂, D₂ (the deuterium, or heavy hydrogen, molecule), HD, and H_2>⁺had elucidated their dissociation energy, ionization potential, and vibrational and rotational levels in the ground state, and permitted close testing of theoretical predictions. By the time of his prize, Herzberg’s NRCC group had studied over sixty such diatomic molecules, providing information about their geometrical structure, electronic structure, and vibrational frequencies in various electronic states.

Equally significant achievements were made on polyatomic molecules, frequently producing spectra of rare chemical species by means of flash photolysis (an excitation and chemical change that follows a brief and intense pulse of light) and, later, flash radiolysis (in which an electron pulse is sent through the absorption cell to produce ions). He and his group had applied such techniques to determine the structures of some thirty short-lived molecular fragments (free radicals), such as free methyl and methylene, that would be difficult to resolve in any other way, and thereby extended understandings of how chemical reactions proceed.

Herzberg relinquished his administrative duties as director of the Division of Pure Physics in 1969 at age sixty-five, but he continued work in a senior role at the NRCC as a distinguished research scientist for a further quarter-century (the last nineteen years being spent at the Herzberg Institute of Astrophysics). In that capacity, he pursued his final and ultimately incomplete quest, the identification of the diffuse bands in interstellar spectra (some one hundred broad spectral absorption lines had been observed by telescope since the 1930s, but not duplicated in laboratory conditions). A further nineteen honorary degrees and twenty-one honorary distinctions followed in the years after his Nobel Prize. Herzberg married Monika Tenthoff in 1972, the niece of his friend Alfred Schulz. He served as chancellor of Ottawa’s Carleton University between 1973 and 1980. Herzberg’s last mark of honor was his appointment as Member of the Queen’s Privy Council for Canada in 1992. After his official retirement from the NRCC in 1994, Gerhard Herzberg’s final five years were spent mainly at home, owing to ill health from a series of heart attacks and Parkinson’s disease.

BIBLIOGRAPHY

A full bibliography of Gerhard’s writings can be found in the microfiche format of Boris P. Stoicheff, “Gerhard Herzberg,”Biographical Memoirs of the Royal Society 49 (2003): 179–186.

WORKS BY HERZBERG

Atomic Spectra and Atomic Structure. Translated by John W. T. Spinks. New York: Prentice-Hall, 1937.

With John W. T. Spinks. Molecular Spectra and Molecular Structure. Vol. 1, Spectra of Diatomic Molecules. New York: Prentice-Hall, 1939.

Molecular Spectra and Molecular Structure. Vol. 2, Infrared and Raman Spectra of Polyatomic Molecules. Princeton, NJ: D. Van Nostrand, 1945.

Molecular Spectra and Molecular Structure. Vol. 3, Electronic Spectra and Electronic Structure of Polyatomic Molecules. New York and London: Van Nostrand Reinhold, 1966.

The Spectra and Structures of Simple Free Radicals: An Introduction to Molecular Spectroscopy. Ithaca, NY, and London: Cornell University Press, 1971.

“Spectroscopic Studies of Molecular Structure.” In Les Prix Nobel en 1971, edited by Wilhelm Odelberg. Stockholm: Nobel Foundation, 1972.

OTHER SOURCES

Claesson, Stig. “The Nobel Prize for Chemistry.” In Les Prix

Nobel en 1971, edited by Wilhelm Odelberg. Stockholm: Nobel Foundation, 1972. The presentation speech for Herzberg’s Nobel Prize.

Nobel Committee. “Gerhard Herzberg.” In Les Prix Nobel en 1971, edited by Wilhelm Odelberg. Stockholm: Nobel Foundation, 1972.

Stoicheff, Boris P. Gerhard Herzberg: An Illustrious Life in Science. Ottawa: NRC Press, 2002.

———. “Gerhard Herzberg.” Biographical Memoirs of the Royal

Society 49 (2003): 179–186.

Sean F. Johnston

Gerhard Herzberg

The German-born Canadian chemist/physicist Gerhard Herzberg (born 1904) was famous for his spectral analysis of molecules and atoms. He was one of only three Canadians to win a Nobel Prize.

Born in Hamburg, Germany, on Christmas day, 1904, he was the younger son of Albin and Ella Herzberg. Gerhard early showed an interest in science. However, his life was disrupted at the age of 10 when his father died, and his mother was later forced to emigrate alone to the United States to work as a housekeeper.

He originally had hoped to become an astronomer but was told by the director of a German observatory that there was no point in going into the field unless he had a private income. So he went on to take a course in engineering physics, supported in part by a scholarship offered by a wealthy industrialist.

His genius showed early, and by the age of 24 he had already published 12 papers on atomic and molecular physics.

In 1924, while at the Darmstadt Technical University, he embarked on work in the area that eventually brought him his Nobel award. After reading Sommerfeld's classic book on atomic structure and spectral lines he fixed on spectroscopy—the study of light waves and other radiation which molecules and atoms can be made to emit or absorb—as his central scientific interest. Having obtained his doctorate in 1928, he spent the following year at the University of Gottingen. There he and a group of other young physicists eagerly applied the principles of quantum mechanics to obtain a fuller understanding of the electronic structures of atoms and molecules.

In 1929 he spent a second post-doctoral year at the University of Bristol in England where he photographed and analyzed the spectra of phosphorus carbide molecules, among others. During this year he returned briefly to Gottingen and married Luise Dettinger, a Jewish physics student. This marriage was to have significant ramifications in Herzberg's life after the Nazis came to power.

From 1930 to 1935 he worked as a privatodozent at Darmstadt Technical University. A privatodozent in the German academic system is able to give private lectures at the university for which he receives a fee. In addition, Herzberg supervised undergraduate laboratories.

At Darmstadt he collaborated in research with the Hungarian-born inventor of the hydrogen bomb, Edward Teller. He also began the first of his attempts to apply his spectroscopic efforts to astrophysics—in this case, the oxygen molecule observed in the atmosphere of the sun.

In 1933 he began to look for work outside of Germany because the Nazis introduced laws banning professors with Jewish wives from teaching at universities. His wife had already begun collaborating with him on a number of papers. In 1935 a former student of his named John Spinks obtained for him a post at the unlikely site of the University of Saskatchewan, located in the middle of the Canadian prairies. He arrived there with the equivalent of $2.50 in his pocket.

Even though the university was nearly bankrupt, Herzberg was able to turn it into a world center for spectrographic research in the ten years he stayed there. He and his wife also began a family, starting with his son Paul, born in 1936, and followed by his daughter Agnes, born in 1938.

While in Saskatchewan he started his work on "free radicals." These are molecular fragments which appear for millioneths of a second when molecules are breaking apart and combining in new structures. These chemical reactions are of increasing interest to atmospheric scientists who are studying their relation to pollution in the Earth's upper atmosphere.

"Knowledge of their (free radicals) importance is of fundamental importance to our understanding of how chemical reactions proceed," said the Nobel committee in giving Herzberg his prize. It took Herzberg 14 years of research before he could identify one of these free radicals.

Herzberg also was one of the first to suggest the existence of molecules in space. His claim was initially disputed by other scientists who thought that the ultraviolet rays which are partially blocked out by the Earth's atmosphere would break down all space-born molecules into simple elements. Herzberg also was able to identify some of the elements that make up comets from spectrographic readings.

Before he left Germany, Herzberg completed the first of his classic books of spectroscopy, entitled Atomic Spectra and Atomic Structure (1937, 1944). Barred from working on major wartime research during much of World War II because he was legally an alien, Herzberg produced the first two volumes of his three-volume work on the structure and spectra of molecules (Molecular Spectra and Molecular Structure, 1939, 1945, 1966). Toward the end of the war the Canadian government put his talents to work analyzing the detonation characteristics of explosives.

In 1945 Herzberg went to Yerkes Observatory, which belongs to the University of Chicago, and stayed there for three years. It was in Chicago that his youthful interest in astronomy and his chemical training were reunited in an extensive analysis of various stellar substances. Unhappy with living in Chicago, he returned to Canada in 1948 to become director of physics at the Canadian government's National Research Council (NRC) in Ottawa, Ontario.

In the region around Ottawa he was able to continue his life-long love of hiking and regularly entertained colleagues and friends alike with his other passion— Germanlieder singing. At the NRC he became a mentor for several generations of Canadian and foreign researchers, impressing them with the unfailing good humor with which he approached life and an almost superhuman capacity for work. When he reached retirement age in 1969, the NRC created its highest grade, distinguished research officer, to allow him to continue his personal research. This he continued to do into his 80s.

It was during this time that he became a leading spokesman against Canadian government efforts to gain more political control over science. He remained a strong advocate of pure research in a Canadian political milieu that increasingly emphasized industry-directed research.

His wife died in 1971, the same year he received the Nobel Prize in chemistry. In 1972 he married Monika Tenthoff, the niece of a close friend he had known during high school.

The Nobel Prize was only one of a number of awards Herzberg received during a scientific career which produced 246 publications. He lectured extensively around the world and received honorary degrees from 35 universities.

About his method of approaching science, Herzberg said in 1984, "In a good sense, I am like a beaver … I don't have all that many problems which are brilliant but if it is a problem I think is important I persist in it."

His contributions to Canadian science were further recognized in 1975 when the NRC's astrophysics and spectroscopy units were reorganized as the Herzberg Institute of Astrophysics, where he continued his research and teaching into his 90s.

Herzberg has added to the lengthy list of accolades and prizes he has already won with awards for scientific achievement from Europe, North America and Japan. In 1987, minor planet 3316=1984 CN1 was officially named Herzberg in his honor.

In 1992, Herzberg was appointed a Member of the Queen's Privy Council for Canada, which is that democratic country's equivalent of a British title. Thus, he became formally addressed as the Honourable Gerhard Herzberg, PC.

Further Reading

There are no book-length accounts of Herzberg's life. A shorter account appears in the The Canadian Who's Who, Toronto: University of Toronto Press, Lumley, Elizabeth, (editor) (1996).

The Internet web facilities provided by the Centre for Systems Science at Simon Fraser University should be browsed for a detailed listing of Herzberg's international scientific awards and an encapsulated biography of his life and achievements. Good information can be found by doing a general search on the internet for "Gerhard Herzberg." □

Gerhard Herzberg

1904-

German-born, Canadian physicist who made significant contributions to a number of areas of science, including molecular spectroscopy, astrophysics, physical chemistry, and quantum mechanics. He is best known for his studies of the structure and geometry of free radicals for which he was awarded the 1971 Nobel Prize in chemistry. He determined the chemical composition of comets through spectroscopic studies, investigated chemical reactions in gases, and studied free radicals as intermediate agents in chemical reactions.