Scientific Career Accomplishments

Publication record of Dr. Robert Norman Compton follows the scientific activities summarized below. The numbers in parenthesis correspond to publications listed on the publications page.

• Established utility of electron scavenger technique in early work on electron attachment (1965-1970)
  Dr. Compton=s earliest work concerned electron attachment to various molecules in gas phase. Out of this came the first implementation of the SF₆ scavenger technique for measuring threshold electron excitation spectra of atoms and molecules. This method was later used by a number of investigators at other laboratories. (Refs. 4, 7, 9, 10, 13, 18, 21, 33, 38)
•  Discovered negative ion resonances in organic molecules (1966-1975)
  The SF₆ scavenger technique was used by Compton to discover negative ion resonances in a number of organic molecules: in particular, benzene naphthalene, etc., and their derivatives. Today many groups are actively pursuing these studies around the world. In 1976, he provided a semiempirical theory describing p-electron affinities for conjugated organic molecules which is widely employed today. (Refs. 4, 6, 7, 9, 10, 13)
•  First determinations of slow electron ionization spectra (1969-1975)
  Complementary to the scavenger technique was his work on threshold spectra utilizing the trapped electron technique. He was the first to measure slow electron ionization cross section for atoms and molecules. Negative ion resonances were also reported in the ionization cross section for He and Ne. (Refs. 19, 20, 31)
•  Established a new technique for determining lifetimes of metastable negative ions (1966-1970)
  Compton was the developer of a time-of-flight method for determining temporary molecular negative lifetimes. In addition, he also introduced a simple theoretical description using quasi-equilibrium theory which is commonly utilized today. (Refs. 3, 10, 22, 30, 33, 41, 47 52)
•  Developed a new method for measuring electron affinities of molecules - his new method became the standard in the field (1971-1975)
  He developed a totally new and very unique method for determining electron affinities of molecules. His alkali-atom-charge exchange is one method for gaining this information. (Refs. 32, 45, 51, 52, 54, 61, 64, 71)
•  Discovered class of super-bound hexafluoride negative ions (1977-1980)
  With his crossed-beam charge-exchange method, he discovered anomalously large electron affinities for a number of exotic hexafluoride molecules (e.g., UF₆). This discovery caused some rethinking on the part of molecular theorists about the ability of molecules to bind an extra electron. (50, 51, 55,71)
•  Discovered a new Atype@ of gas phase ionic chemical reactions (1977)
  Dr. Compton was the co-discoverer of thermal energy gas phase collisional ionization process between ground state reactant species, namely Cs and UF₆. This was a new type of gas phase reaction. (Refs. 51, 55)
•  Development of a negative ion isotope separation scheme was undertaken on the basis of his work (1979)
  His work on UF ions led to his suggestion for new isotope separation scheme for uranium isotopes. This suggested method was implemented with Compton=s encouragement by researchers at Argonne National Laboratory and showed some promise as a feasible scheme for commercial separation. Compton also holds patents on new surface ionization methods of producing intense beams of actinide-metal hexafluoride negative ions. (Refs. 50, 51, 55)
•  Co-developer of molecular cluster technique for studies of ion chemistry (1977-1978)
  With Cornelius E. Klots, Compton developed pulsed nozzle molecular clustering methods for studies of negative ions and discovered stable ions in gas phase clusters which did not exist in monomeric species. Of particular significance are his unique studies of (CO) and (CO₂) cluster ions. The study of negative clusters is being pursued by numerous groups around the world. (Refs. 53, 59, 60)
•  Introduced a two-color laser spectroscopic technique (1979)
  In collaboration with a postdoctoral fellow, A. D. Williamson, Compton first introduced a sequential multiphoton excitation spectroscopic method which is widely used in nonlinear spectroscopy. The technique allows for higher sensitivity and extreme selectivity in laser spectroscopy. The method is finding many uses in isotope separation and analytical chemistry. (Refs. 65, 88, 95, 101, 110)
•  Introduced multiphoton technique for the accurate determination of ionization potentials of molecules (1979)
  Along with A. D. Williamson and J. H. D. Eland, Compton introduced a new laser multiphoton ionization method for the determination of ionization potentials of molecules. This technique, combined with the two-color spectroscopic method, provides the most accurate ionization potentials for molecules presently available. (Ref. 63, 73)
•  Co-discoverer of new effect in resonant multiphoton ionization processes (1980-1990)
  Dr. Compton and John Miller were chiefly responsible for the experimental discovery of a new phenomenon in multiphoton ionization processes involving an interference between third harmonic generation and three-photon excitation of optically allowed transitions in atomic systems. This accidental discovery is being recognized as important in many areas of nonlinear optics. Although originally observed for atoms, the effect is now being reported in many molecules and is referred to as Acoherent control of chemistry@ in this context. Similar cancellation effects are being reported in general wave-mixing phenomena. (Refs. 72, 82, 88, 91, 101, 135)
•  Made first molecular spectroscopic application of third harmonic generation (1980)
  He has, with John C. Miller, made pioneering application of third harmonic generation methods to molecular spectroscopic studies. These studies received an IR-100 award as one of the one-hundred most significant discoveries in 1982. (Refs. 80, 81, 82, 86, 91, 93)
•  Introduced a new area of spectroscopy: AMultiphoton Ionization Photoelectron Spectroscopy@ (1979-present)
  Dr. Compton, along with John C. Miller, introduced multiphoton ionization photoelectron spectroscopy as a unique method in laser spectroscopy. This technique has allowed for new studies in nonlinear laser spectroscopy and provided the first measurements of photoelectron spectroscopy of excited states of atoms and molecules. These studies were the first in a rapidly growing area of laser spectroscopy which is expanding today. A major review chapter (ref. 126) was published in 1989. (Refs. 69, 78, 79, 83, 84, 89, 96, 97, 107, 110, 111, 116, 119, 120, 121, 125, 126, 127, 130, 131, 134, 138, 141, 143, 192)
•  Multiphoton ionization studies in external electric fields (1984)
  Dr. Compton and C. E. Klots made the first measurements of multiphoton ionization in an external electric field. These studies are currently being pursued by others. (Ref. 103, 104)
•  Photoelectron angular distributions following multiphoton ionization: experiment and theory (1984-present)
  Along with graduate students (A. Dodhy, Auburn University; P. Blazewicz, Yale; L. Cuéller and S. Bajic, University of Tennessee) and others, Compton has measured the angular distributions of photoelectrons resulting from multiphoton ionization (MPI) of alkali atoms and rare gas atoms. These measurements have been compared with the theories of Lambropoulos (USC) and Pindzola (Auburn). This work represents a systematic, scholarly, and detailed treatment of MPI. In one Physical Review Letter (PRL) the group has measured angular distributions of photoelectrons resulting from multiphoton ionization (MPI) the group has measured angular distributions for two-photon ionization near the threshold (electron kinetic energy -0.02 eV). In another PRL, a study of photoionization of ns states of cesium provided the first clear evidence of spin-orbit continuum effects on a photoelectron angular distribution. A recent paper provides the first measurements of the circular dichroism effects on photoelectron angular distributions. (Refs. 96, 97, 107, 110, 111, 119, 120, 138, 143)
•  Developed new method of autodetachment spectroscopy for study of metastable negative ions (1985)
  Compton, in collaboration with G.D. Alton and D. J. Pegg, developed a new accelerator-based spectroscopic technique for studying the properties of highly metastable negative ions, such as He ^- and Be^- . Alton, Compton, and Pegg made the first measurements on the energy levels for many negative ions such as Be^-. This remains the first and only such measurements on this important class of anions. (Refs. 75, 94, 108)
•  Made first measurements of the properties of metastable noble gas molecular negative ions (1986)
  Compton and coworkers have established several of the properties (electron affinity, vibrational frequencies, electronic configuration) of metastable negative ions of the helium diatomic molecular He. Previous to these measurements it was only known that long-lived (t > 1ms)He^- ions existed. (Ref. 112)
•  Discovered stable negative ion of calcium (1984)
  Compton, G. Alton, and D. J. Pegg (University of Tennessee) and J. S. Thompson (graduate student, University of Tennessee now at Univ. Nevada Reno) developed a new technique involving photoelectron detachment spectroscopy of fast-moving (- 6500 keV) negative ion beams. The fast beam photoelectron spectroscopy technique provides for an order of magnitude improvement in electron energy resolution. Using this technique they have discovered that Ca^- (4s²4p)²P is stable (electron affinity = 0.043 " 0.007 eV). Previous to this study, it was believed that none of the Group IIA metal atoms could bind an extra electron. (Ref. 117)
•  Collisional M_j mixing probed by multiphoton ionization (1986-1990)
  Compton, together with graduate students S. Bajic and L. D. Snow (University of Tennessee) have measured collisional relaxation rates and optical dephasing rates using novel multiphoton ionization techniques for atoms (Xe,Kr) and a molecule NO. In the former studies, theoretical analysis was provided by the USC group (Lambropoulos, et al.). (Refs. 121, 135)
•  Observation of doubly charged carbon clusters (1989-present)
  Compton collaborated with the group of Peter Williams (S. Schauer, P. Williams, and R. N. Compton) to provide the first clear evidence for doubly charged negative ions in the gas phase. Stable C ions were observed for n = 7. Along with R. Hettich and R. H. Ritchie, Compton has observed the C₆₀^-2 ion from laser ablation of graphite and laser desorption from metal surfaces. C₆₀^-2 has also been described theoretically. A major invited review in Science (ref. 190) is a definitive survey of the field. (Refs. 139, 144, 148, 163, 190)
•  Theoretical studies of the photophysics of He^-(2s22p)⁴P⁰ (1989-1991)
  Compton and colleagues had earlier provided the first measurements of the photodetachment cross sections for He^-4P⁰. In a collaboration with H. P. Saha, a complete theoretical analysis of the photodetachment and radiative attachment cross sections was determined. Photoelectron angular distributions were also calculated and compared with earlier measurements. (Refs. 133, 136, 142)
•  Studies of Rydberg atom charge exchange cross sections with electronegative molecules (1988-present)
  Carman, Klots, and Compton have made unique observations of the electron exchange reactions of highly excited (n = 10 - 50) Rydberg atoms with SF₆, CS₂, HI, and other gases. These authors found an unexpected but dramatic n dependence in the reactions. In addition, a pronounced isotope effect favoring the sulphur-34 isotope of CS₂ was observed which may lead to a new isotope separation scheme. Observations of HI^- in the reaction C^* + HI -> C⁺ + HI ^- provided the first evidence for diabatic electron attachment reactions and may change the way one thinks about "thermal" electron attachment reactions. (Refs. 128, 137, 149, 154, 164, 165, 166, 167, 168)
•  Fundamental mechanisms of laser ablation (1989-present)
  Graduate student M. J. Shea (Vanderbilt University) and Compton have performed fundamental studies of laser ablation of surfaces. The first study involved laser ablation of hydrogen (deuterium) loaded palladium. In a second paper the authors provide clear evidence for the effect of surface plasmon ejection of Ag⁺ ions from roughened surfaces of silver. (Refs. 140, 146, 147, 158, 168, 170, 172)
•  Studies of buckyball and other fullerenes (1990-present)
  Very recently, Compton has led an interdisciplinary effort at ORNL and UT to study the generation, separation, characterization, chemistry, and spectroscopy of fullerenes. (Refs. 139, 144, 146, 148, 150, 151, 152, 154, 156, 157, 159, 160, 161, 162, 166, 167, 169, 170, 172, 173, 174-185, 190, 191, 193)
•  Entrepreneurial accomplishments in the field of atomic, molecular, and optical physics (1979-present)
  Compton co-founded Comstock, Inc., in 1979. This company presently employs five professional scientists and seven technical personnel who provide instruments of general interest to the atomic and molecular physics community. For example, Comstock has sold over 400 electrostatic energy analyzers used in photon and charged particle ionization studies. Comstock has sold over twenty optical Aheat pipes@ used in many basic and applied research areas such as third-harmonic generation, stimulated electronic Raman scattering, etc. Time-of-flight mass spectrometers are employed in many areas of basic and applied research. Other optical research instruments are provided such as multiphoton ionization and laser ablation of surfaces. Basic research is also carried out at Comstock for the development of new research applications and products.
•  Establishment of a physical chemistry laser spectroscopy laboratory at The University of Tennessee (1988-present)
  Over the past ten years Compton has constructed a laser spectroscopy laboratory centered around the use of a nitrogen pumped dye laser. Experiments involve the use of optical heat pipes, multiphoton ionization cells, and other linear and nonlinear optical experiments. A number of these experiments have been published, one in a new textbook to be used in physics and physical chemistry laboratories. (Ref. 148)

Presentations

R.N. Compton has made over 100 presentations, seminars, etc. since 1990. Some of the Invited Presentations since 1992 are:

2. Multiphoton Ionization Photoelectron Spectroscopy of Atoms and Molecules, 43rd Okasaki Conference on Laser Photoelectron Spectroscopy, Okazaki, Japan, March 9-13, 1992 (plenary lecture).

3. On the Generation, Separation, Physics and Chemistry of Large Carbon Clusters, 181st Electrochemical Society Meeting, St. Louis, Missouri, May 17-22, 1992.

4. The Physics and Chemistry of Large Carbon Clusters, 45th Annual Gaseous Electronics Conference, Boston, Massachusetts, October 27-30, 1992 (plenary lecture). Talk given along with R.L. Hettich.

5. Fifty Years of Atomic and Molecular Physics at Oak Ridge, Southeastern Section of the American Physical Society, Oak Ridge, Tennessee, November 12-14, 1992.

6. Carbon Clusters and Fullerenes, Division of Atomic, Molecular and Optical Physics of the American Physical Society, Reno, Nevada, May 17-19, 1993.

7. The Physics and Chemistry of Fullerenes, International Conference on Local Order in Condensed Matter Physics, Jekyll Island, Georgia, June 14-17, 1993.

8. Materials Research on Nanoclusters at Oak Ridge National Laboratory, Exxon Research and Engineering Company, Annandale, New Jersey, January 19, 1994.

9. Spherical Molecular Architectures: Fullerene Derivatives, American Physical Society Annual Meeting, Pittsburg, Pennsylvania, March 23-25, 1994.

10. Fullerene Ions, Optical Society of America Annual Meeting/ILS-X, Dallas, Texas, October 2-7, 1994.

11. Boron and Nitrogen Doped Fullerenes, 70th Colloid and Surface Science Symposium (ACS), Clarkson University, Potsdam, New York, June 11-19, 1996.

12. Thermionic Emission, 8th International Resonance Ionization Spectroscopy Conference, Pennsylvania State University, June 29-July 5, 1996.

13. Synthesis of Doped Fullerenes, Annual American Chemical Society Meeting, Orlando, Florida, August 25-30, 1996.

14. Negative Ions of Atoms, Molecules and Clusters, 32nd Symposium für Theoretische Chemie für Kleine Molecule in der Gasphase, Graz, Austria, September 20-25, 1996 (plenary lecture).

15. Multiply Charged Anions, Sanibel Conference on Theoretical Chemistry 1998 (Plenary Lecture)

16. Chirality in Nature Prestige Lecture, University of Canterbury, Christchurch, New Zealand (1998)

17. Multiply-Charged Negative Ions, American Physical Society, Atlanta, Ga. March (1999)