Marilyn Jacox, a Pioneer in Infrared Spectroscopy

Marilyn Jacox, PhD, was a pioneer in the infrared (IR) and electronic spectroscopies of free radicals and small molecular ions in matrix isolation. Before Jacox's recent passing, Ingeborg Iping Petterson had the pleasure of speaking with her about her career in spectroscopy. Jacox shared her personal story, reflections on her extensive career, and insight and advice for young scientists, especially women, who are just starting their careers.

Marilyn Jacox was born in 1929 in Utica, New York. Her father was a master baker, and her mother was a homemaker. Her parents possessed great intellectual ability but lacked the educational opportunities to become scientists themselves. Both came from single-parent homes with modest finances, and her father left school in the seventh grade to find a job.

Her parents supported her interest in school and getting good grades, and eventually her budding science career. "They played very different roles, but one of the big things was that I was accepted," said Jacox. "My parents' dream for me when I was small was that I would continue in music, get a respectable office job, marry, and raise a family. When I began to have a successful science career, my father was intensely proud of his little girl, and my mother just plain accepted me."

Figure 1: Marilyn Jacox outside her home near Gaithersburg, Maryland, in April 2013.

Jacox grew up in the Depression, a time when most women in the United States did not drive, and many did not even write checks. Those were tasks for the male head of a household. The three generally accepted professions for women then were teaching, nursing, and secretarial business positions. Jacox started out studying business in high school because she thought that would give her the best prospect for a future job. She concluded that the business practices that she learned in her mandatory "Introduction to Business," course and typing skills she learned served her well throughout her career.

She joked that her friends in school teased her that she only received good grades because she studied easy subjects. "But when I switched focus in my junior year and began doing college preparatory courses, my grades went up!" she recalled. She also remembered a young woman with whom she rode the bus, whose dream of studying chemistry inspired her to do the same. "I knew then that a college preparatory curriculum would help me."

Figure 2: Jacox looking at a photograph of herself from 1973, when she was working at the National Bureau of Standards.

Early Mentors

As a young child, Jacox was passionate about music. She took voice and piano lessons from several different music teachers, including various women living in her neighborhood. Then a family moved into a house down the block, and the man was a professional musician. "He became my music teacher for most of the remaining time during which I studied music, and that made an enormous difference in my progress," Jacox said. "I translated that into 'If a young woman is seeking an education in science, she should go get the best education and best teachers she can.'"

Her first scientific mentor, John C. Keller, her undergraduate supervisor from the Department of Chemistry at Utica College of Syracuse University, was indeed an excellent scientist. "In this world, it makes a lot of difference who your teachers are, and he was the best," she said. "I think this point is very important to pass along to young women who are highly motivated in science."

Oscar K. Rice from the University of North Carolina, with whom she worked after her graduate study at Cornell University, was another important mentor. "He was a wonderful person in every sense, a superb scientist yet very unassuming," she said. Jacox talked about many of her mentors in her autobiographical article, "On Walking in the Footsteps of Giants" (1).

Another important influence on Jacox's career was her long-time collaboration with Dolphus "Dick" Milligan, which began when Jacox became a Fellow at Mellon Institute of Industrial Research in Pittsburgh. The director of the Mellon Institute had a mandate to encourage new research, and she and Milligan were appointed at this opportune time. Although her first research studies were on the IR spectroscopy of molecular solids, soon she began to collaborate with Dick in his studies of free radicals.

Jacox felt that her work with Milligan played an important role in her professional development. "He had information and experimental ideas left over from his Berkeley thesis, and he wanted to test them," she recalled. "In the beginning of our collaboration the ideas were his. I learned from him, and after collaborating for a modest period of time, sometimes we didn't know who had the idea first, and alternated first authorship of our publications."

Career Challenges as a Woman Scientist

When considering the obstacles she faced professionally, Jacox named three areas of challenge. "I sum it up when I tell people about the rough times for me as a woman, as a government worker, and as a scientist doing matrix isolation of small molecules," she said.

Jacox observed gender bias firsthand early in her career, when she was seeking an academic position after completing postdoctoral research in 1958 at the University of North Carolina. Despite the national excitement about science following the launch of Sputnik by the Russian space team, her résumé received a favorable response only from women's colleges. "I had never really liked the idea of separate men's and women's colleges, because in the real world you need to be able to deal with both men and women," she said. When she saw that coed schools would not hire a woman, she broadened her job search and eventually landed an appointment as a Fellow at the Mellon Institute. But that did not mean equal pay; her long-term collaborator, Dick Milligan, another Fellow, earned more. "This gender-based disparity was widespread," she recalled.

The gender bias was not limited to pay, however. "The culture of the organization when I arrived was like something out of the 'Mad Men' television show," she said. "The guys went to a local pub for lunch, and would go golfing together. These were very 'guy things' to do, and the culture was very male dominated. It is much less so now."

Jacox recalled a few specific examples, including one when she and Dick Milligan were new at the Mellon Institute. "Our work was advancing at a healthy rate, and he was friends with a next-up manager who was planning a cocktail hour at his home, to which he invited Dick, but not me," she recalled. Since Dick was married with two small children, she often gave him rides to work functions so that he could leave the family car with his wife. This time, too, she drove Dick to the party and waited for him in the car.

That was around 1959. But another example occurred more than a decade later, many years after Jacox and Milligan had both moved to the National Institute of Standards and Technology (NIST), in Gaithersburg, Maryland, which was then called the National Bureau of Standards (NBS). In early 1972, a Canadian scientist they knew was in town and gave a seminar. Some of the older male scientists arranged for him to stay at the Cosmos Club in downtown Washington, DC, and arranged a dinner in his honor there the evening after his seminar. This time, both Milligan and Jacox were invited. "We went home in the evening, changed, and Dick arrived at the Cosmos Club just before I did," Jacox recounts. "He went to the front door, and even though Dick was black, there was no problem at all; Dick was directed to the room where the dinner was held." Not so for Jacox.

It was a rainy day and she had parked about a block away, and by the time she made it to the front door, she was drenched. "An elderly man answered and told me that ladies could not come in the front door, but had to use the side entrance," she said. Before she could catch her breath, he took a second look, decided to have mercy, and let her in. "I never forgave the Cosmos Club for that injustice," she said. "I have since been invited to join, but have replied 'Thanks, but no thanks'."

Although Jacox was pleased to see a lot of progress of women in recent years, she didn't expect sexism to go away. "Young boys go through a stage where they band together and build tree houses and don't like girls; some guys grow up and some stay in that psychological state," she said. "It's not likely to change. Where it matters most is in organizations with limited funding resources. The guys have their own special ways of communicating among themselves and getting themselves at the top of the list."

As a result, Jacox said, women must step up to make names for themselves in the scientific community. "Stand on your feet and present your stuff — in academia and also in industry," she declared. "Too many young women shy away from that kind of thing. If you don't go to the meetings or present results you are not going to get very far in science."

A good, solid publication record is vital, she continued. "Young women need to get participating in the scientific community, and they need to see the research through to its publication."

When Jacox published, she felt it was important to use her full name, so that people knew she was a woman. She remembered discussing this with another woman scientist at the Mellon Institute. "She and I never agreed on how to handle our names," Jacox recalled. "When she applied for meetings she put her name on her papers with just her first and middle initial. I preferred, then and now, always to use my full first name. Using just your initials doesn't help other women."

On Working in Government, and the Federal Women's Award

Jacox moved from the nonprofit Mellon Institute to NIST in 1962. Although Jacox felt that the situation for women scientists was generally a bit better at NIST, working at a government research institute also presented challenges. In Jacox's view, government workers often do not receive the respect they deserve, and that can lead to resource limitations. "Frankly, since the late 1970s, government has been perceived as a part of the problem." she said. "This public mindset has been exploited by both political parties, and government employees and their funding have not been totally respected because of where the work has been done."

Within government, there was also a lack of recognition of the achievements of women. But in 1960, Julia Lee, a vice president at Woodward & Lothrop, a major department store in downtown Washington, DC, decided to do something about that. "Julia used her clout as a corporate vice president to establish a Federal Women's Award, given to six women each spring," Jacox explained. Awardees were drawn from all of the federal government agencies, nominated by their personnel departments. Jacox received the award in 1973. "It was nicely arranged," she said. "That award has not been given since about 1975, but the women who did receive it had this common bond, and we have stayed in contact."

Advancing the Study of Small Molecules

Jacox's career is important not only because of her leading role as a spectroscopist at a time when few women were prominent in the field, but also because she did pioneering work using IR spectroscopy to study the structure of small molecules trapped in matrix isolation. Matrix isolation of unstable molecules in solid noble gases was developed in the early 1950s (2) and Jacox was one of the first scientists to use this technique extensively to study the IR spectra of free radicals (3).

"Scientifically, there wasn't much known [at the time] about spectra of free radicals, and Dick [Milligan] and I had a tool to observe these spectra, because the IR spectrum is to a molecule what a fingerprint is to you," she said. "Herzberg's two first spectroscopy volumes had not been available for very long when we began our work, so for many small molecules much was still unknown."

Jacox noted that one of the challenges with her work arose because she didn't see spectra of molecules in the gas phase, but rather frozen in solid argon or neon. The interaction energy between an argon or a neon atom and a molecule is minimal but non-zero, implying that small spectral shifts occur. "People used that as a reason to question my data," she said.

To address that problem, Jacox started a database comparing the positions of gas-phase band centers with the positions of the corresponding absorption maxima observed in various inert, rigid matrix environments. She found that the infrared absorptions of small polyatomic free radicals trapped in solid argon or neon usually appear within 1% of corresponding gas-phase band centers. "When the argon- or neon-matrix position of a free-radical absorption has been identified, this generalization becomes a useful tool in the search for the gas-phase absorption," she explained. "Through the years, this generalization was key to my scientific survival." The compilation grew and matured into the "Vibrational and Electronic Energy Levels" section of the NIST Chemistry WebBook, available on the internet (4).

"Basically, my measurements are qualitative," she continued. "In order to be able to see free radicals at all you've got to have a spectrum, and you have to prove what the carrier of the spectrum is. That's the part I most enjoy." She noted that as analytical chemistry has grown enormously over the past 50 years, there has been a greater drive for quantitative analysis. Although matrix isolation measurements are not well suited to that, they interface very well with quantum chemistry.

"It's been fun to interact with quantum chemists," she said. "It used to be that vibrational fundamental calculations for free radicals were very approximate. Recently, computers and computational procedures have developed that enormously."

A split in the field of molecular spectroscopy also occurred, Jacox observed, between chemical spectroscopic analysis and studies of the nature of the chemical bond. "As a physical chemist, I'm biased toward studying the properties of chemical bonds," she said. "Even though computational chemists are getting to the point where, jokingly, I say that they are putting me out of business, refinements in computational procedures need to be checked by comparison with experimental data."

In talking about all the scientific problems in this area yet to be solved, Jacox sounded like a scientist in mid-career, not someone in her eighties. And in fact, she continued to do research at NIST, as a scientist emerita until her passing.

"Calculations are not so well developed for excited electronic states," she said. "Even more complexity is required to study crossings of potential surfaces, which are ubiquitous."

She also commented that another question far from being pinned down is the relationship between the details of spectra and chemical reactivity. "There are lots of applications in which that could be important, ranging from the chemistry of interstellar matter to various industrial and environmental chemical processes," she said. "Interaction with quantum chemical calculations will continue to become more important to the field."

Achievements and Satisfaction

Jacox experienced a lot of satisfaction in her career. "Each publication is a milestone for me," she said. "I don't have a perfect track record, but I have a respectable one, and it's very interesting to watch where the results of your work go."

When Jacox was hired at NIST (then called NBS), the Free Radicals Program had recently finished. "It revolutionized chemistry at NBS," she said. "They were at the end of a generation of chemists, and it inspired the hiring of many new, talented people." Indeed, Jacox, and her friend and colleague Dick Milligan, were two of the talented scientists hired to continue research into free radicals, which was still a hot topic, even though the formal program had ended.

What Jacox called her own "Mount Everest," however, involved moving beyond free radicals to the spectroscopic study of small molecular ions, which are often several orders of magnitude more reactive than are free radicals. "I had ideas about how molecular ions could be produced and stabilized, and how I could study their spectra," she said. "These ideas worked. I have been studying primarily the spectra of molecular ions for 25 years now." Mass spectrometry, she pointed out, gives primarily the empirical composition, not structure. "If you are clever enough, sometimes you can pin a given fragmentation pattern to a specific structure [using mass spectrometry] but most of the time the structural information isn't there."

During Jacox's time at NIST, the laser soon began to be important, and Jacox envisioned that laser scientists would pick up where matrix measurements left off. Gradually more and more complicated molecules would be discovered, she thought, and the field and tools would develop in such a way that it would become possible to study larger and larger species. Instead, she watched as funding agencies shifted priorities and as a result the scientific community moved in the new direction, heavily focused on the properties of nanostructures.

Jacox also lamented that most of the citations of her work are to the older part of her work, rather than on her later studies. "I had hoped to see where the molecular ion results would lead during my lifetime, but I am beginning to think I will need to be more than 100 years old to see that!"

Advice for Young Scientists

Jacox conceded that pursuing a career such as hers was not easy, and thus would recommend it only to young scientists who are truly motivated. "Too often young people are getting their degrees in science, only to face a difficult job market," she said.

Her advice is essentially the same for young women considering a career in her field. "For a young woman graduate student, I would recommend my field if she is good at it and really enjoys it, but if she doesn't have that to begin with I would not try to point her in that direction," she said. But once a student decides to pursue a scientific path, and has committed to a graduate advisor, she should see it through to her degree, Jacox believed. "The advisor invests time, interest, and intellectual capital in a graduate student, and if that person drops out, that can be very disappointing to the advisor." That same dedication to completing work should continue throughout a woman's career, she added. "More generally, if a woman is committed to a project that yields publishable results, she should see it all the way to publication. She should also begin to participate in meetings as soon as she can."

A Passionate Scientist and a Role Model

Visiting with Marilyn Jacox at her home near Gaithersburg, Maryland, revealed the experiences of a scientist with an impressive scientific career, and provided a glimpse into what a scientific career was like for women during the 1950s, 1960s, and 1970s.

At the end of the interview, Jacox pulled out an enlarged portrait photo, from around 1973, taken in her laboratory at NIST. She joked that the glasses she is wearing in the photo have come back into style, and that not much has changed about the design of the round bottom flask that she is holding.

"I have loved the research I have done, and I would like to keep my finger on what is happening in the field," she said. "I would like to remain available to scientists who have questions in my area of expertise, in order to help as much as I can in advancing research."

Even in the months before her passing, Jacox's desire to learn never waned. She spoke enthusiastically of a recent trip to Baja, Mexico, to photograph whales from an inflatable boat, and of her plans to travel to Alaska later that year. With her drive to explore the world — from small molecules to whales — Marilyn Jacox is a role model for all.

Acknowledgments

The author wishes to thank Walter Lafferty for providing background and historical information, Jesse Rowton for taking the photos seen here, and Ellen Miseo for proposing the original idea for this interview and article.

References

(1) M.E. Jacox, Ann. Rev. Phys. Chem. 61, 1–18 (2010).

(2) E. Whittle, D. A. Dows, and G. C. Pimentel, J. Chem. Phys. 22, 1943 (1954).

(3) M.E. Jacox. Chem. Soc. Rev. 31(2), 108–115 (2002).

(4) M.E. Jacox, in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, P.J. Linstrom and W.G. Mallard, Eds. (NIST, Gaithersburg Maryland, 2011).

Ingeborg Iping Petterson is an associate research fellow in the department of Biomedical Physics at the University of Exeter in Devon, the United Kingdom. Direct correspondence to: ii209@exeter.ac.uk