Robert J. McMahon
VerifiedOhio State University · History
Active 1953–2026
About
Robert J. McMahon is the Ralph D. Mershon Distinguished Professor Emeritus in the Department of History at The Ohio State University. He joined the department in Fall 2005 and has previously taught at the University of Florida from 1982 to 2005, as well as held visiting positions at the University of Virginia and University College Dublin. His expertise lies in the history of U.S. foreign relations, with a focus on diplomatic history, human conflict, peace, and diplomacy. Professor McMahon is the author of several significant works, including 'Colonialism and Cold War: The United States and the Struggle for Indonesian Independence, 1945-49,' 'The Cold War on the Periphery: the United States, India, and Pakistan,' and 'The Limits of Empire: The United States and Southeast Asia since World War II.' He has also served as president of the Society for Historians of American Foreign Relations in 2000. His research and teaching focus on American history since 1877, U.S. foreign relations, and diplomatic history, contributing to the understanding of U.S. involvement in global conflicts and diplomacy.
Research topics
- Chemistry
- Political science
- History
- Physics
- Atomic physics
Selected publications
Journal of Quantitative Spectroscopy and Radiative Transfer · 2026-01-06
articleJournal of the American Chemical Society · 2026-03-30
articleOpen accessSenior authorCorrespondingWe measured and analyzed the microwave (11–35 GHz) and millimeter-wave (85–750 GHz) rotational spectra of the normal isotopologue of cyclopropanone and nine additional isotopologues. The ability to perform experimental measurements is predicated on the synthesis of stable oligomers (or polymers) of cyclopropanone that release the monomeric form under vacuum to enable the investigation of cyclopropanone by gas-phase rotational spectroscopy. The spectral data provided in this work establish the foundation for radioastronomical searches for cyclopropanone. In particular, the new low-frequency microwave observations provide hyperfine-resolved rotational transitions that are necessary for radioastronomical observations at the low temperatures that characterize many cold interstellar molecular clouds. The extensive isotopic data set allows the first complete semiexperimental equilibrium (reSE) structure of cyclopropanone. The 10 isotopologues used in this structure determination provide 30 moments of inertia. As a result, the values of all six independent structural parameters are highly converged, establishing a new experimental benchmark for the structure of this archetypal organic molecule. The highly precise and accurate reSE structure was compared to a computed equilibrium (re) structure at the CCSD(T)/cc-pCV6Z level with additional corrections addressing finite basis set, higher-level electron correlation, and relativistic effects, as well as the diagonal Born–Oppenheimer correction. The computed re structure systematically deviates from the reSE structure, despite the high-level methodology utilized. This finding is interpreted as revealing a subtle, but real, challenge for theoretical chemistry in predicting molecular structure at the level of accuracy that is now attainable experimentally.
The Journal of Physical Chemistry A · 2026-04-24
articleOpen accessSenior authorCorrespondingThe rotational spectrum of the normal isotopologue of 1,3-oxazole (c-C3H3NO) was observed from 43 to 750 GHz. Over 3900 transitions for the ground vibrational state are measured, assigned, and least-squares fit to sextic centrifugally distorted-rotor Hamiltonians. The measured frequencies and resulting spectroscopic constants from this extended spectral range, combined with previous measurements of the nuclear quadrupole coupling constants, will facilitate astronomical searches for oxazole across the majority of the range of modern radiotelescopes. Spectra for a set of 30 oxazole isotopologues, which include multiple isotopic substitutions of each atom, are used to determine the first semi-experimental equilibrium (reSE) structure and semi-experimental substitution structure (rsSE), each using CCSD(T) computed values for the vibration–rotation interaction and electron-mass corrections. The large number of isotopologues, including 21 isotopologues observed for the first time, and the redundant substitutions of each atom provide sufficient spectroscopic information to determine the reSE structure with the expected high level of accuracy and precision (0.0001 or 0.0002 Å in bond distances and 0.013 to 0.025° in bond angles). In the course of this study, we analyzed a known issue for some reSE structure determinations of near-oblate asymmetric tops in which inclusion of individual isotopologues degrades the structure determination. We demonstrate that this problem primarily arises from the difference in the values of the computed vibration–rotation interaction corrections as evaluated at the computed re geometry vs the reSE geometry of the “real” molecule. Our solution to this problem substantially improves the reSE structure of oxazole and likely can be generalized to many other molecules.
The Journal of Physical Chemistry A · 2025-09-04
articleOpen accessSenior authorCorrespondingThe rotational spectra and analysis of the two lowest-energy vibrationally excited states, ν19 (A′, 126 cm–1, MP2) and ν27 (A″, 133 cm–1, MP2), of s-trans-(Z)-1-cyano-1,3-butadiene from 130 to 375 GHz is presented. The state symmetries allow a- and b-type Coriolis coupling, the effects of which are observed due to the close energy spacing of these states. A combined total of 6744 transitions were modeled (σfit < 60 kHz) with a partial-octic two-state A-reduced Hamiltonian including eight coupling parameters (Ga, GaJ, Fbc, FbcJ, Gb, GbJ, GbJJ, and GbK). The vibration–rotation interaction constants, Coriolis ζ terms, and energy difference between the states were determined experimentally and are compared to predicted values (B3LYP/6-311+G(2d,p) and MP2/6-311+G(2d,p)). The coupled-state analysis affords a precise vibrational energy difference of 5.753 373 1 (25) cm–1 between the two fundamental states. Several matching pairs of a- and b-type resonant transitions, as well as many formally forbidden, nominal interstate transitions, are included in the final least-squares fit. (E)- and (Z)-1-Cyano-1,3-butadiene are possible precursors to or degradation products of pyridine, a fundamental aromatic molecule of interest in the interstellar medium. There is currently some uncertainty concerning the reported identifications of other cyanobutadiene isomers in the interstellar medium. Combined with our previously reported ground-state spectroscopic constants, the vibrationally excited-state constants provided herein enable possible extraterrestrial identification of multiple vibrational states of s-trans-(Z)-1-cyano-1,3-butadiene.
<i>Fire and Rain: Nixon, Kissinger, and the Wars in Southeast Asia</i> by Carolyn Woods Eisenberg
The Journal of Interdisciplinary History · 2025-01-01
article1st authorCorrespondingEisenberg delivers a painstakingly detailed and devastating account of the Vietnam War policies of President Nixon. She joins a crowded field of study, to be sure. Historians, political scientists, journalists, memoirists, and others have probed nearly every aspect of the conflict in Indochina, much as they have scrutinized in granular detail the peculiar partnership between Nixon and Henry A. Kissinger, his national security adviser and top foreign policy aide. Yet Eisenberg manages to surpass all previous scholarly efforts with this empirically rich, crisply written, and analytically astute monograph. Rooted in exhaustive research and brimming with fresh insights, this book is a triumph of traditional diplomatic-military history.Eisenberg covers the period from Nixon’s inauguration in January 1969 to the signing of the deeply flawed Paris peace accords four years later. The book’s first half examines the administration’s attempts to combine steady U.S. troop withdrawals—to placate a domestic audience eager to bring the war to a close—with tactical military escalations designed to pressure North Vietnam into accepting a settlement favorable to U.S. interests. The central contradiction of that strategy, the author makes clear, lay in the illusion that the administration “could somehow wrest a victory on the battlefield or at the negotiating table with ever-diminishing numbers of American troops” (333–334). It could not. Following the calamitous Laotian incursion of February 1971, which baldly exposed the limits of “Vietnamization,” Nixon and Kissinger fundamentally altered their strategy.From that point forward, a period covered in the second half of the book, they turned to their nominal communist adversaries, the Soviet Union and China, for help in extricating the United States from the morass of Vietnam. In so doing, the White House revealed to Moscow, Beijing, and the wider world another core contradiction of its Vietnam policy: that a war begun and rationalized as a valiant effort to halt the expansion of the communist monolith would wind up with U.S. leaders beseeching the two major communist powers for their assistance in its ending. Yet that gambit, too, fell short, producing tens of thousands of needless deaths, millions of refugees, and a peace settlement that amounted to little more than a fig leaf for the final exit of U.S. troops and the return of U.S. prisoners of war. Eisenberg’s empathetic focus on the victims of U.S. decision-making stands in welcome contrast to studies that confine themselves entirely to the perspective of the decision-makers. “The Nixon administration’s conduct of the war—in Vietnam, Laos, and Cambodia—was a failure that yielded a tsunami of personal tragedies for both Americans and Asians,” Eisenberg concludes. “Yet nobody was ever held accountable” (14).This book draws from an extraordinary tranche of archival records, perhaps unique for any presidential administration before or since, supplemented by dozens of interviews with former Vietnamese officials. The notorious White House tape recordings, coupled with the verbatim transcripts of Kissinger’s telephone conversations, allow Eisenberg to give an unvarnished, fly-on-the wall account of the two principals’ deliberations, replete with example after example of amoral callousness, deceit, double-dealing, sycophancy, and self-delusion—punctuated with frequently crude, profane language. “I’d finish off the goddamn place,” Nixon stormed about the North Vietnamese at one point. “Just knock the shit out of them” (340). “We will keep our chins up and keep kicking them in the balls,” he exclaimed at another (380). In a typical rant, Kissinger chimed in: “They’re shits … they are tawdry, miserable, filthy people. They make the Russians look good” (473). Nor did the South Vietnamese fare much better in his assessment. President Nguyen Van Thieu was described as “an unmitigated, selfish, psychopathic person, son-of-a-bitch” (480).Eisenberg attributes some of the policy-making pathologies that she dissects with such withering precision to the personal psychological pathologies of her two main characters, referring throughout to their grandiosity, vanity, jealousy, insecurity, mood swings, and emotional instability. Yet she never engages with the one discipline—psychology—that might have helped her reach a deeper comprehension of those behavioral issues. That limitation aside, this remains an outstanding work of scholarship that deserves a wide readership.
The Journal of Chemical Physics · 2025-10-08 · 4 citations
articleSenior authorMicrowave and millimeter-wave rotational spectra of 46 thiophene isotopologues are used to determine a new semi-experimental equilibrium (reSE) structure for thiophene. The large dataset of isotopologues-roughly twice as large as any dataset used for a semi-experimental equilibrium structure determination for a molecule of this size-and the broad frequency coverage enable a detailed investigation concerning previously reported discrepancies between the structural parameters of the reSE and re structures of thiophene. The observation of rotational spectra for 23 new thiophene-dx isotopologues, many with additional 34S or 13C substitution at natural abundance, is made possible by the high sensitivity of the PARIS FTMW spectrometer in the microwave frequency region. Frequency coverage for thiophene and single heavy-atom isotopologues in the millimeter-wave region has been expanded to include the range of 82-750 GHz. Bond distances and bond angles of the new highly precise and accurate reSE structure are determined with precisions of ≤0.0002 Å and ≤0.02°, respectively. This study provides strong evidence that the discrepancies can be addressed only by improvements to the theoretical re structure and that the precision and accuracy of the semi-experimental equilibrium (reSE) structural parameters are approaching the limit of structure determination.
The Journal of Physical Chemistry A · 2025-11-07 · 5 citations
articleOpen accessSenior authorCorrespondingMillimeter-wave rotational spectra of 32 pyridine isotopologues have been measured within the 80–750 GHz frequency range. The rotational constants resulting from analysis of these spectra, corrected for the effects of vibration–rotation interactions and electron-mass distributions using CCSD(T)/cc-pCVTZ calculations, enable the determination of a highly precise semiexperimental equilibrium structure (reSE) of pyridine. The structural parameters of pyridine are in generally good agreement with those of previously published reSE structures, but the precision achieved here is substantially improved: bond lengths are determined to ±0.0002 Å and bond angles are determined to ±0.020° (2σ uncertainties). Such precision approaches the limit of semiexperimental equilibrium structure determination using a contemporary methodology. The current investigation provides critical structural data that enables a detailed analysis of the effects of nitrogen-atom substitution in prototypical aromatic molecules. Only through comparisons among recently determined, highly precise structures for benzene, pyridine, pyridazine, and pyrimidine are the subtle structural effects of nitrogen-atom substitution in the aromatic ring experimentally revealed.
The Journal of Physical Chemistry A · 2025-10-29 · 2 citations
articleOpen accessSenior author) are treated by effective Hamiltonians, owing to their complex anharmonic- and Coriolis-coupling interactions. The experimental spectroscopic constants and vibrational energies are compared to their computed values (CCSD(T)/cc-pCVTZ).
The Journal of Physical Chemistry A · 2024-02-14 · 6 citations
articleSenior authorCorrespondingThe gas-phase rotational spectrum of 1-cyano-2-methylenecyclopropane (C1, C5H5N), an isomer of pyridine, is presented for the first time, covering the range from 235 to 500 GHz. Over 3600 a-, b-, and c-type transitions for the ground vibrational state have been assigned, measured, and least-squares fit to partial-octic A- and S-reduced distorted-rotor Hamiltonians with low statistical uncertainty (σfit = 42 kHz). Transitions for the two lowest-energy fundamental states (ν27 and ν26) and the lowest-energy overtone (2ν27) have been similarly measured, assigned, and least-squares fit to single-state Hamiltonians. Computed vibration–rotation interaction constants (B0–Bv) using the B3LYP and MP2 levels of theory are compared with the corresponding experimental values. Based upon our preliminary analysis, the next few vibrationally excited states form one or more complex polyads of interacting states via Coriolis and anharmonic coupling. The spectroscopic constants and transition frequencies presented here form the foundation for both future laboratory spectroscopy and astronomical searches for 1-cyano-2-methylenecyclopropane.
Médecine et Maladies Infectieuses Formation · 2024-05-28
articleSenior author
Recent grants
Organic Chemistry in Harsh Reaction Environments
NSF · $565k · 2017–2021
NIH · $56k
Organic Chemistry in Harsh Reaction Environments
NSF · $545k · 2014–2018
Mechanistic Organic Chemistry of Relevance to Astrochemistry
NSF · $525k · 2010–2014
Mechanistic Organic Chemistry of Relevance to the Interstellar Medium.
NSF · $480k · 2004–2008
Frequent coauthors
- 185 shared
Brian J. Esselman
University of Wisconsin–Madison
- 105 shared
R. Claude Woods
University of Wisconsin–Madison
- 79 shared
John F. Stanton
University of Florida
- 61 shared
Maria A. Zdanovskaia
University of Wisconsin–Madison
- 44 shared
Samuel M. Kougias
University of Wisconsin–Madison
- 38 shared
Robert L. Kuczkowski
University of Wisconsin–Madison
- 28 shared
Robert J. Halter
University of Wisconsin–Madison
- 27 shared
Jens‐Uwe Grabow
Leibniz University Hannover
Education
- 1985
Ph.D. Chemistry, Department of Chemistry and Biochemistry
University of California Los Angeles
- 1980
B.S. Chemistry
University of Illinois at Urbana-Champaign
Awards & honors
- President of the Society for Historians of American Foreign…
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