Earle K. Plyler: Setting the Standard in Infrared Spectroscopy

This article features Earle K. Plyler, a pioneering figure in molecular spectroscopy. Plyler’s contributions to infrared spectroscopy, molecular vibrations, and optical materials characterization established new standards for precision in spectroscopic measurement and analysis. Widely recognized for his instrumental innovations and meticulous experimental work, Plyler also mentored future leaders in the field, including Walter Gordy. His enduring impact is honored through the Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics, awarded annually by the American Physical Society since 1977.

Introduction to An Infrared Visionary at the Precision Frontier

From water vapor lines to complex hydrocarbon spectra, Earle K. Plyler devoted a half-century to making infrared spectroscopy both exquisitely accurate and broadly useful (3–9,12). Beginning in academia (UNC Chapel Hill, then Michigan) and culminating in two decades at the National Bureau of Standards (NBS), Plyler’s program unified careful metrology with molecular physics, producing line lists, band centers, and instrument innovations that became bedrock for generations of spectroscopists (9,10). In later years, he carried that standard‑first ethos to Florida State University, mentoring students and building programs in the American Southeast (7,12).

Earle K. Plyler (c. 1962) from (1)

Early Life and Education: Carolina Roots, Columbia Doctorate

Earle Keith Plyler was born April 26, 1897, in Greenville, South Carolina (7,14). He earned the A.B. (1917) and A.M. (1918) at Furman University, pursued graduate work at Johns Hopkins, and completed the Ph.D. in physics (1924) at Columbia University (7). A Physics Today’s obituary reports that Plyler “died 8 May in Tallahassee, Florida” (5), while multiple reference sources (including [7] and cemetery records [14]) list June 8, 1976. Given the contemporaneous Physics Today notice, May 8, 1976 is likely correct.

Building an Academic Base at UNC and Michigan Years (1924–1945)

Plyler joined the University of North Carolina (UNC) at Chapel Hill in 1924, rising through the faculty and establishing a reputation in infrared spectroscopy (6,7). In 1941, he moved to the University of Michigan, continuing spectrum analyses during the wartime years (7). UNC’s departmental history also records his Carolina ties and subsequent NBS career (6).

National Bureau of Standards: Working with Precision, Line Lists, and Reference Data (1945–1962)

At NBS in Washington, D.C., Plyler led influential efforts in infrared spectroscopy and radiometry, eventually heading the Infrared Spectroscopy Section (7,9,15). His group produced painstaking measurements of fundamental and overtone bands, rotational structure in polyatomics, and benchmark vibrational analyses—foundational work preserved across Journal of Research of the NBS/NIST (9) and The Journal of Chemical Physics (10).

Earle Plyler adjusting the lens of a high-resolution spectrometer at the National Bureau of Standards (1952) from (2).

Florida State University as a Department Builder and Mentor (1962–1970s)

Rather than retire, Plyler accepted the chair of Physics at Florida State University in 1962 (3), helping expand spectroscopy and chemical physics in Tallahassee and attracting world leaders. For example, he received recurring visits and appointments by figures such as Robert S. Mulliken in the 1960s (12,15).

Publications and Research Examples

Plyler’s research spanned the full breadth of infrared and molecular spectroscopy, blending fundamental studies of molecular vibrations with practical advancements in optical instrumentation. His work focused on refining spectroscopic measurement techniques across the mid- and far-infrared regions, developing improved optical components, filters, and calibration methods to achieve higher precision and reproducibility. Plyler conducted detailed investigations of the vibrational and rotational spectra of organic and inorganic molecules, providing data that became essential for molecular structure determination and chemical identification (12).

In parallel, he carried out studies of infrared optical materials—such as alkali halides and other crystalline substances—characterizing refractive indices, dispersion relationships, transmittance, and reflectance over wide wavelength ranges. These measurements established reference values widely adopted in spectroscopy laboratories. Plyler’s combination of instrumental innovation, materials characterization, and molecular analysis helped define modern infrared spectroscopy practice, influencing both theoretical interpretation and applied measurement techniques. His contributions bridged the gap between pure research and the practical needs of scientists and engineers working in spectroscopy and optics (12).

Plyler authored more than 100 papers in total spanning spectra and constants for small molecules, hydrocarbons, and atmospheric species (9,10,12). A few representative, accessible publications include:

“Vibrational Spectra of Trifluoroethylene and Trifluoropropene.” J. Chem. Phys. 1954, 22, 1586–1593 (10).

High-resolution analyses and line positions are archived in the NBS/NIST corpus. See NIST Journal of Research entries by A. D. Baker, T. A. O’Keefe, W. B. Olson, A. Maki, and coauthors working with Plyler (9).

Many additional Plyler papers are indexed in AIP and NIST collections; the NIST Journal of Research gateway provides bibliographic access (9).

Mentorship Training: the Next Wave of Molecular Spectroscopists

Among Plyler’s most noted doctoral students was Walter Gordy, who completed his Ph.D. at UNC under Plyler and later founded the molecular microwave spectroscopy program at Duke University (11). Plyler’s NBS group also incubated talent such as W. S. Benedict, W. B. Olson, and A. G. Maki, collaborators whose spectral standards became widely used (9,11).

Special Service: Standards, Community, and Editorial Work

Plyler’s NBS leadership formalized infrared reference data, aligning instrumentation, calibration practices, and reporting conventions at a time when spectroscopy was rapidly diversifying (9,15). His community service is reflected in his obituaries and reminiscences documenting section leadership at NBS and active engagement across spectroscopy societies (5,15).

Personality of an Exacting, Generous, and Unfailingly Curious Scientist

Colleagues remembered Plyler as a thorough experimentalist with a generous collaborative spirit—insisting on careful assignment and error budgets while remaining open to new molecules, methods, and students (5,15). Contemporary sources emphasize his international reputation and collegial warmth (5).

Honors and Recognition: The APS Earle K. Plyler Prize

Since 1977, the Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics has honored “notable contributions to the field of molecular spectroscopy and dynamics” (3,4,8). The prize, administered by the American Physical Society (APS) and now associated with The Journal of Chemical Physics, consists of $10,000, travel support, and an invitation to contribute a perspective article (3,4,8).

A Legacy of Infrared Standards that Still Illuminate

Plyler’s influence persists wherever accurate molecular spectra matter—atmospheric retrievals, combustion diagnostics, astrochemistry, metrology, and beyond (7,9). By marrying precision measurement with molecular physics, he made infrared spectroscopy a quantitative language that modern spectroscopists still speak. The APS Plyler Prize keeps that legacy vibrant, tying today’s breakthroughs back to the standards he helped define (3,8).

References

(1) Image Credit Line: AIP Emilio Segrè Visual Archives. Portrait—Earle Plyler. Available at: https://repository.aip.org/portrait-earle-plyler-0 (accessed 2025-08-14).

(2) Image Credit Line: AIP Emilio Segrè Visual Archives. Earle Plyler Adjusting Lens of High-Resolution Spectrometer, National Bureau of Standards. Available at: https://repository.aip.org/earle-plyler-adjusting-lens-high-resolution-spectrometer-national-bureau-standards (accessed 2025-08-14).

(3) American Physical Society. Earle K. Plyler Prize for Molecular Spectroscopy & Dynamics; APS: College Park, MD. Available at: https://www.aps.org/funding-recognition/prize/plyler (accessed 2025-08-14).

(4) American Physical Society, Division of Chemical Physics Honors, Prizes and Awards. Available at: https://engage.aps.org/dcp/honors/prizes-awards (accessed 2025-08-14).

(5) Barr, E. S. Earle K. Plyler. Phys. Today 1976, 29 (11), 84. Available at: https://pubs.aip.org/physicstoday/article-pdf/29/11/84/8280379/84_1_online.pdf (accessed 2025-08-14).

(6) University of North Carolina, Department of Physics & Astronomy. Section I — Department History (selected entries). Available at: https://physics.unc.edu/home/department-history/section-i/ (accessed 2025-08-14).

(7) Wikipedia. Earle K. Plyler. Available at: https://en.wikipedia.org/wiki/Earle_K._Plyler (accessed 2025-08-14).

(8) Wikipedia. Earle K. Plyler Prize. Available at: https://en.wikipedia.org/wiki/Earle_K._Plyler_Prize (accessed 2025-08-14).

(9) NIST. Journal of Research of the National Bureau of Standards / NIST — Search Results Including Plyler Coauthorships. Available at: https://www.nist.gov/search?s=Earle+K.+Plyler (accessed 2025-08-14).

(10) Plyler, E. K. Vibrational Spectra of Trifluoroethylene and Trifluoropropene. J. Chem. Phys. 1954, 22, 1586–1593. Available at: DOI: 10.1063/1.1740463

(11) Duke University. Walter Gordy (1909–1985), Molecular Microwave Spectroscopy at Duke. Available at: https://physics.duke.edu/about/history/historical-faculty/walter-gordy (accessed 2025-08-14).

(12) Earle K. Plyler, Optica Publications List. Available at: https://opg.optica.org/search.cfm?q=Earle+K.+Plyler&ibsearch=false (accessed 2025-08-14).

(13) NIST. Gallery of Distinguished Scientists, Engineers, and Administrators—2022 Program Brochure. Available at: https://www.nist.gov/document/portrait-gallery-2022-program-brochure (accessed 2025-08-14).

(14) Find a Grave. Earle Keith Plyler (1897–1976) — Memorial. Available at: https://www.findagrave.com/memorial/33484308/earle-keith-plyler (accessed 2025-08-14).

(15) Barr, E. S. Spectroscopy in the U.S.A. to World War II (with Notes on Later Careers). Available at: https://pages.cs.wisc.edu/~david/Geneaology/EL_Nichols-AO.pdf (accessed 2025-08-14).

About the Author

Jerome Workman, Jr. serves on the Editorial Advisory Board of Spectroscopy and is the Executive Editor for LCGC and Spectroscopy. He is the co-host of the Analytically Speaking podcast and has published multiple reference text volumes, including the three-volume Academic Press Handbook of Organic Compounds, the five-volume The Concise Handbook of Analytical Spectroscopy, the 2nd edition of Practical Guide and Spectral Atlas for Interpretive Near-Infrared Spectroscopy, the 2nd edition of Chemometrics in Spectroscopy, and the 4th edition of The Handbook of Near-Infrared Analysis. He is the recipient of the 2020 NYSAS Gold Medal Award (with Howard L. Mark). Author contact: JWorkman@MJHlifesciences.com ●