# Robert W. Field
**Robert W. Field** (born 1944 in [Wilmington, Delaware](https://www.edgepedia.org/wilmington-delaware)) is an American physical chemist and molecular spectroscopist who studies the structure and dynamics of small gas-phase molecules. He spent his career at the [Massachusetts Institute of Technology](https://www.edgepedia.org/massachusetts-institute-of-technology), joining the Chemistry faculty in 1974 and holding the Robert T. Haslam and Bradley Dewey Professorship from 1999; MIT now lists him as Professor Emeritus.[1](https://web.mit.edu/rwfield/www/CV.html) • [2](https://chemistry.mit.edu/profile/robert-w-field/) His group works with two or more tunable lasers running simultaneously, together with chirped-pulse millimeter-wave techniques, to read structural and dynamical information out of small molecules.[2](https://chemistry.mit.edu/profile/robert-w-field/) He is known for spectroscopic perturbations, for the multiple-resonance and stimulated emission pumping (SEP) methods he helped invent, and for the textbook *The Spectra and Dynamics of Diatomic Molecules*.
| Fact | Detail |
|---|---|
| Born | 1944, Wilmington, Delaware[1](https://web.mit.edu/rwfield/www/CV.html) |
| Training | A.B. chemistry, Amherst College, 1965; Ph.D. and M.A., Harvard University, 1972, supervised by William A. Klemperer; postdoc with H.P. Broida and D.O. Harris at UC Santa Barbara, 1971–1974[1](https://web.mit.edu/rwfield/www/CV.html) |
| Career | MIT Chemistry faculty from 1974: Assistant Professor 1974–1978, Associate Professor 1978–1982, Professor 1982–1999, Haslam, and Dewey Professor from 1999, now Emeritus[1](https://web.mit.edu/rwfield/www/CV.html) • [2](https://chemistry.mit.edu/profile/robert-w-field/) |
| Signature work | SEP spectroscopy (first experiments on I2, 1978) and the 2015 *Science* paper extracting transition-state energies from frequency-domain spectra[4](https://pubs.acs.org/jpcafh/article/113/47/13045/931047/Autobiography-of-Robert-W-Field) • [5](https://www.science.org/doi/10.1126/science.aac9668) |
| Books | *Perturbations in the Spectra of Diatomic Molecules* (1986); *The Spectra and Dynamics of Diatomic Molecules* (2004)[1](https://web.mit.edu/rwfield/www/CV.html) |
| Major honors | Broida (1980), Plyler (1988), Lippincott (1990), Meggers (1996), Bomem-Michelson (2006), Schawlow (2009) prizes |[6](https://www.optica.org/History/Biographies/bios/Robert_W_Field) • [3](https://www.biographies.net/people/en/robert_w_field)
| Editorial role | Editorial Board, *Journal of Molecular Spectroscopy*, from 1976[1](https://web.mit.edu/rwfield/www/CV.html) |
## Career
Field majored in chemistry at [Amherst College](https://www.edgepedia.org/amherst-college), taking an A.B. magna cum laude in 1965.[1](https://web.mit.edu/rwfield/www/CV.html) His graduate work at Harvard, supervised by William A. Klemperer, gave him his initial experience with multiple-resonance spectroscopies and spectroscopic perturbations, the two themes that ran through the rest of his career; he received his Ph.D. and M.A. in 1972.[1](https://web.mit.edu/rwfield/www/CV.html) As a postdoc with H.P. Broida and D.O. Harris at UC Santa Barbara's Quantum Institute (1971–1974), he performed the first microwave-optical and optical-optical double resonance studies of diatomic molecules using tunable lasers.[1](https://web.mit.edu/rwfield/www/CV.html) • [6](https://www.optica.org/History/Biographies/bios/Robert_W_Field)
He joined the MIT Chemistry faculty in 1974 and moved through the ranks to the named Haslam and Dewey professorship in 1999.[1](https://web.mit.edu/rwfield/www/CV.html) He served on the Editorial Board of the *Journal of Molecular Spectroscopy* from 1976.[1](https://web.mit.edu/rwfield/www/CV.html)
## Research
**Spectroscopic perturbations.** According to MIT News, his 1996 Meggers Award citation recognized his definitive studies of perturbations in diatomic molecular spectra.[7](https://news.mit.edu/1996/awards-0110)
**Multiple resonance and SEP.** Stimulated emission pumping (SEP) is a method for sub-[Doppler spectroscopy](https://www.edgepedia.org/doppler-spectroscopy) and efficient state-selective preparation of highly excited rotational-vibrational levels of small molecules.[8](https://doi.org/10.1063/1.442324) Field's first SEP experiments were on I2 in 1978, and formaldehyde and acetylene served as the first polyatomic test molecules.[4](https://pubs.acs.org/jpcafh/article/113/47/13045/931047/Autobiography-of-Robert-W-Field) SEP, a technique invented at MIT, gives access to vibration-rotation excitation of small polyatomic molecules at chemically significant amounts of excitation.[2](https://chemistry.mit.edu/profile/robert-w-field/) A 1986 *Annual Review of Physical Chemistry* article established SEP as a new method in spectroscopy and molecular dynamics,[9](https://www.annualreviews.org/content/journals/10.1146/annurev.pc.37.100186.002425) and a 2001 follow-up review covered its use for intramolecular vibrational redistribution, unimolecular isomerization, and dissociation, and energy transfer in highly vibrationally excited molecules.[10](https://www.annualreviews.org/content/journals/10.1146/annurev.physchem.52.1.811) Applied to highly excited vibrational levels of polyatomic molecules at MIT, SEP yielded the first experimental evidence for quantum manifestations of classical chaos in an isolated molecule.[1](https://web.mit.edu/rwfield/www/CV.html)
**Transition states.** A PNAS study used millimeter-wave spectroscopy of products from the UV breakdown of vinyl cyanide and found both HCN and HNC among the products, evidence of two different transition states; because a transition state lasts only a few femtoseconds, its structure was read indirectly from the vibrational population distribution of products observed microseconds after the reaction.[11](https://chemistry.mit.edu/chemistry-news/chemists-glimpse-the-fleeting-transition-state-of-a-reaction/)
## Representative work
His 2015 paper in *Science*, ["Spectroscopic characterization of isomerization transition states"](https://doi.org/10.1126/science.aac9668), demonstrated a method for extracting transition-state energies and properties from a characteristic pattern in frequency-domain spectra of isomerizing systems. It was applied to the cis-trans conformational change in the S1 state of acetylene and to the bond-breaking HCN–HNC isomerization; in both cases the barrier heights derived from spectroscopic data agree extremely well with previous ab initio calculations.[5](https://www.science.org/doi/10.1126/science.aac9668) MIT News reported the result as the experimental characterization of a chemical state long believed impossible to observe, and quoted Field: "This was supposed to be impossible because of the intrinsic complexity, but we found the magic decoder that enables us to go deeper into this regime."[12](https://news.mit.edu/2015/map-unobservable-chemical-state-1210)
Two book-length works anchor the field: *Perturbations in the Spectra of Diatomic Molecules* (1986) and *The Spectra and Dynamics of Diatomic Molecules* (Elsevier, 2004), an expanded treatment of the same subject; he also authored *Spectra and Dynamics of Small Molecules: Alexander von Humboldt Lectures* (2015).[1](https://web.mit.edu/rwfield/www/CV.html) • [2](https://chemistry.mit.edu/profile/robert-w-field/)
## Honors and recognition
Field's prizes trace the arc of his methods: the Herbert P. Broida Prize (1980), the Earle K. Plyler Prize (1988), the Ellis R. Lippincott Award (1990), the William F. Meggers Award (1996), the Coblentz Society Bomem-Michelson Award (2006) and the Arthur L. Schawlow Prize in Laser Science (2009).[6](https://www.optica.org/History/Biographies/bios/Robert_W_Field) The 1990 Nobel Laureate Signature Award of the American Chemical Society recognized SEP studies of acetylene from his group.[6](https://www.optica.org/History/Biographies/bios/Robert_W_Field) He is a Fellow of the [American Physical Society](https://www.edgepedia.org/american-physical-society) (1981), the Optical Society of America (1994), the American Academy of Arts and Sciences (1998), AAAS and the Royal Society of Chemistry, and received a [Doctor of Science](https://www.edgepedia.org/doctor-of-science) honoris causa from Amherst College in 1997.[1](https://web.mit.edu/rwfield/www/CV.html) • [6](https://www.optica.org/History/Biographies/bios/Robert_W_Field) • [13](https://pubs.acs.org/jpcafh/article-pdf/113/47/13064/9988207/jp9093194.pdf) He is a member of the National Academy of Sciences.[3](https://www.biographies.net/people/en/robert_w_field)
## Recent developments
The transition-state program continued into 2025: a [Nature Communications paper](https://doi.org/10.1038/s41467-024-55253-3) published on 3 January 2025 (volume 16, article 76) used [double resonance spectroscopy](https://www.edgepedia.org/double-resonance-spectroscopy) to reveal structure and dynamics near transition states, noting that experimental characterization of the transition state was long thought unattainable but that modern techniques have begun to achieve it; for a dissociation reaction this means characterizing the minimum energy path toward bond breaking, the instantaneous structure of nascent fragments, and the transition-state energy above the equilibrium structure.[14](https://www.nature.com/articles/s41467-024-55253-3) His group at MIT remains active on small gas-phase molecules with multi-laser and chirped-pulse millimeter-wave methods.[2](https://chemistry.mit.edu/profile/robert-w-field/)
## Students and legacy
According to MIT News, more than 30 students had completed their PhD research in Field's group as of 1996.[7](https://news.mit.edu/1996/awards-0110) His methods spread well beyond it: SEP enables sub-Doppler spectroscopy and state-selective preparation of highly excited rotational-vibrational levels of small molecules,[8](https://doi.org/10.1063/1.442324) and a 2016 *Journal of Chemical Physics* perspective he co-authored marked the first ten years of broadband chirped-pulse [Fourier transform microwave spectroscopy](https://www.edgepedia.org/fourier-transform-microwave-spectroscopy).[15](https://rwf.mit.edu/group/group/papers.html) A 2019 *Nature Communications* paper on the dicarbon bonding puzzle, published 15 November 2019, stands among his later contributions to molecular bonding questions.[16](https://www.nature.com/articles/s41467-019-13039-y)
## References
1. Robert W. Field, Curriculum Vitae (MIT). https://web.mit.edu/rwfield/www/CV.html
2. Robert W. Field – MIT Department of Chemistry. https://chemistry.mit.edu/profile/robert-w-field/
3. Biography of Robert W. Field. https://www.biographies.net/people/en/robert_w_field
4. Autobiography of Robert W. Field, *J. Phys. Chem. A* 113, 13045 (2009). https://pubs.acs.org/jpcafh/article/113/47/13045/931047/Autobiography-of-Robert-W-Field
5. Spectroscopic characterization of isomerization transition states, *Science* (2015). https://www.science.org/doi/10.1126/science.aac9668
6. Robert W. Field, Optica biography. https://www.optica.org/History/Biographies/bios/Robert_W_Field
7. Awards and Honors, *MIT News* (1996). https://news.mit.edu/1996/awards-0110
8. Selective vibrational excitation by stimulated emission pumping, *J. Chem. Phys.* https://doi.org/10.1063/1.442324
9. Stimulated Emission Pumping: New Methods in Spectroscopy and Molecular Dynamics, *Annu. Rev. Phys. Chem.* 37, 493–524 (1986). https://www.annualreviews.org/content/journals/10.1146/annurev.pc.37.100186.002425
10. The Dynamics of 'Stretched Molecules', *Annu. Rev. Phys. Chem.* 52, 811 (2001). https://www.annualreviews.org/content/journals/10.1146/annurev.physchem.52.1.811
11. Chemists glimpse the fleeting "transition state" of a reaction, MIT Chemistry News. https://chemistry.mit.edu/chemistry-news/chemists-glimpse-the-fleeting-transition-state-of-a-reaction/
12. MIT chemists characterize a chemical state thought to be unobservable, *MIT News* (2015). https://news.mit.edu/2015/map-unobservable-chemical-state-1210
13. Awards and Honors of Robert W. Field, *J. Phys. Chem. A* (PDF). https://pubs.acs.org/jpcafh/article-pdf/113/47/13064/9988207/jp9093194.pdf
14. Double resonance spectroscopy reveals structure and dynamics near transition states, *Nature Communications* 16, 76 (2025). https://www.nature.com/articles/s41467-024-55253-3
15. Robert W. Field Group, Selected Recent Publications. https://rwf.mit.edu/group/group/papers.html
16. The dicarbon bonding puzzle viewed with photoelectron imaging, *Nature Communications* (2019). https://www.nature.com/articles/s41467-019-13039-y
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Chemists › Researchers in physical, theoretical, and computational chemistry › Spectroscopy theory and ultrafast/attosecond dynamics*
*Initially written Sep 21, 2026 · Reviewed: Sep 25, 2026 · Edited: Sep 25, 2026; Oct 12, 2026; Oct 15, 2026 · Last review: Sep 25, 2026*
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