University of Vermont

College of Arts and Sciences

Department of  Physics

Faculty Research

The Department of Physics offers research opportunities in astrophysics, acoustical physics, biophysics, condensed matter physics, the physics of materials, and the history of physics.

Astrophysical research centers on experimental radio astronomy, with particular emphasis on pulsars and the interstellar medium. Observations are carried out using major instruments of the U.S. National Observatories and generally involve computer analysis and interpretation.

Research in biological physics is being pursued in three areas: atomic-force microscopy, to study the structures of biological materials at the submicroscopic level, ultrasonic biophysics, studying the physics of the interaction of ultrasound with living systems, and structural dynamics, looking at the changes in protein structure associated with function. These areas involve collaboration with the College of Medicine. Acoustical and optical tweezers, being developed here, permit manipulating single cells without touching them. Theoretical and experimental studies of the biological effects of ultrasound emphasize the modeling of possible effects on humans. New forms of ultrasonic transducers and biosensors are being developed in collaboration with Electrical Engineering, as part of the Materials Science Program. The research area of biological atomic force microscopy (AFM) is focused on the use of state-of-the-art technology to study biological systems under their native conditions. The goals are to determine the structure of macromolecular and micromolecular assemblies at sub-micrometer resolution, and to study dynamic processes of proteins and membranes in real time. X-ray crystallographic studies of proteins structure tells us not just what the machinery of life looks like but how it much move in order to accomplish biological function.

Theoretical and computational research programs in condensed matter physics deal with electronic, optical, lattice-dynamical, thermodynamic, surface, and magnetic properties of metals, semiconductors, superconductors, laser crystals, and biological materials. Materials of current interest include transition and rare-earth metals, fullerides and fullerenes, ordered, disordered, amorphous and liquid metals and alloys, ionic solids, and doped elemental and compound semiconductors. Some of the general approaches include the analytical and numerical methods of self-consistent band theory, crystal-field theory, multiple-scattering theory, Green's function formalism, and density-functional theory. Experimental condensed-matter physics includes the nonlinear interaction of materials with ultrasound, as well as the submicroscopic structure of biological materials.

Theoretical studies of the optical properties of materials include the electronic structure of defect complexes in ionic crystals, the application of subtracted dispersion relations to optical data analysis, and the separation of inter- and intra-band effects in the infrared spectra of metals. Related studies are concerned with theories of X-ray scattering, of X-ray optical properties, and of X-ray optical elements.

Other faculty members are active in the history and philosophy of physical science, with particular regard to the way in which it evolves. Particular interests include the relationships among science, society, and technology issues in the physical sciences. Several faculty members also collaborate in local and national applied efforts and research in improving physics education.

Current opportunities for collaborative research with other University departments and groups include those with Chemistry, the Materials Science Program, Molecular Physiology and Biophysics, the Cell and Molecular Biology Program, Computer Science and Electrical Engineering.

The Department participates in two doctoral programs: Materials Science and Cell and Molecular Biology.

Laboratory facilities for work in biophysics and condensed matter physics are supplemented by computational facilities that include the campus-wide network.


Robert G. Arns
Professor Emeritus

The evolution of new knowledge never follows the neat deductive sequence presented in physics textbooks. The work of Thomas Kuhn and others has helped show the human drama and agony in the evolution of scientific understanding and the connections between the advance of science and other aspects of the human experience. Analogous patterns are found in the development of applications from scientific discoveries. Professor Arns is engaged in research on the history of modern physics and on the evolution of technologies derived from specific discoveries. The results of this work have significance for physics education, for public policy relative to the support of research and development, and for the management of scientific and technological change in industry.

Prof. Arns has a B.S. degree from Canisius College and M.S. and Ph.D. degrees from The University of Michigan. He has numerous publications in experimental nuclear physics. Work in progress includes continuing research on: 1) the persistence of ether concepts in the 20th century; 2) the influence of naive beliefs on the development of scientific understanding; and 3) the history of the field-effect transistor.

  • R.G. Arns and B. Crawford, Resonant Cavities in the History of Architectural Acoustics, Technology and Culture, 36, No. 1, 104-35 (Jan. 1995).
  • R.G. Arns, Preconceptions in Introductory Physics Courses, Conference on the Introductory Physics course, J. Wilson, ed. (John Wiley and Sons, Inc., New York, 1997), pp. 159-164.
  • R.G. Arns, The High-vacuum X-ray Tube: Technological Change in Social Context (Technology and Culture, 1995), 38, No. 4, 552-590 (October 1997).

Kelvin Chu
Associate Professor

Proteins are biological molecules that catalyze many of the reactions necessry for life. They are made from a highly condensed polymer chain of amino acids and are, consequently, not rigid. In fact, many proteins need to be able to switch between a number of physical conformations in order to work. Protein dynamics strive to connect the intricacies of structure, and the motion between related structures, with biological function. Our efforts center on trying to understand the physics of how proteins work by determining the functional consequences of protein structure and protein dynamics. We use both time-resolved and equilibrium spectroscopies (visible, FT-IR), coupled with crystallographic methods to study the dynamics and, ultimately, the structure of proteins as they do their job. Systems of interest include heme proteins, such as myoglobin and hemoglobin, as well as several of the non-heme diiron proteins.

Kelvin Chu received his Sc.B. degree from Brown University and his M.S. and Ph.D. from the University of Illinois at Urbana-Champaign. He was a postdoctoral fellow at Los Alamos National Lab.

  • Frauenfelder H, McMahon BH, Austin RH, Chu K, Groves JT. (2001) "The role of structure, energy landscape, dynamics, and allostery in the enzymatic function of myoglobin." Proc Natl Acad Sci USA.. 98:2370 -2374.[Entrez]
  • Schlichting I, Chu Kelvin (2000) "Trapping intermediates in the cr ystal: ligand binding to myoglobin." Curr Opin Struct Biol. 10:744 -752.[Entrez]
  • Schlichting I., Berendzen J., Chu, Kelvin, Stock A.M., Maves S.A., Benson D.E., Sweet R.M., Ringe D., Petsko G.A., Sligar S.G . (2000) ''The catalytic pathway of cytochrome P450cam at atomic resolution.'' Science 287:1615-1622. [Entrez]
  • Brunori, M., Vallone, B., Cutruzzola, F., Travaglini-Allocatelli, C., Berendzen, J., Chu, Kelvin, Sweet, R. M. and Schlichting, I. (2000) ``The role of cavities in protein dynamics: crystal structure of a novel photolytic intermediate of myoglobin.'' Proc. Natl. Acad. Sci., USA 97:2058-2063. [Entrez]
  • Chu, Kelvin, Vojtechovsky, J., McMahon, B., Sweet, R. M., Berendzen, J., and Schlichting, I. (2000) ``Crystal structure of a new ligand-binding intermediate in wildtype carbonmonoxymyoglobin.'' Natu re 403:921-923. [Entrez]
  • Vojtechovsky, J., Chu, Kelvin, Berendzen, J., Sweet, R. M., and Schlichting, I. (1999) ``Crystal structures of myoglobin-ligand complexes at near-atomic resolution.'' Biophys. J. 77:2153-217 4. [Entrez]
  • Terwilliger, T.C., Waldo, G., Peat, T.S., Neuman, J.M., Chu, Kelvin, and Berendzen, J (1998) ``Class-directed structure determination: foundation for a protein structure initiative.'' Protein Sci 7:1851-1856. [Entrez]
  • Nienhaus, G.U., Chu, Kelvin, and Klemens, J. (1998) ``Structural heterogeneity and ligand binding in carbonmonoxy myoglobin crys tals at cryogenic temperatures.'' Biochem. 37:6819-6823. [Entrez]

Dennis P. Clougherty
Professor and Chair

Dr. Clougherty's research is concerned with several topics in theoretical condensed matter physics, including high Tc superconductivity, magnetism, quantum sticking, density functional theory, and the properties of fullerenes and nanotubes.

Dr. Clougherty received his B.S. degrees in Physics and Electrical Engineering, his M.S. degree in Electrical Engineering, and his Ph.D. degree in Physics from M.I.T. He was a postdoctoral fellow at the University of California-Santa Barbara. He has had visiting appointments at M.I.T., University of California-San Diego, Harvard University, University of Texas at Austin, and the Institute for Theoretical Physics, Santa Barbara, California. He serves as a consultant for several corporations and laboratories.

  • Di Xiao, Junren Shi, D.P. Clougherty, and Qian Niu, Polarization and Adiabatic Pumping in Inhomogeneous Crystals, Phys. Rev. Lett. 102, 087602 (2009).
  • T.E. Jones, M.E. Eberhart and D.P. Clougherty, Topology of the Spin-polarized Charge Density in bcc and fcc Iron, Phys. Rev. Lett. 100, 017208 (2008).
  • D.P. Clougherty, Jahn-Teller Solitons, Structural Phase Transitions and Phase Separation, Phys. Rev. Lett. 96, 045703 (2006).
  • M.E. Eberhart and D.P. Clougherty, Looking for Design in Materials Design, Nature Materials 3, 659 (2004).
  • D.P. Clougherty, Anomalous Threshold Laws in Quantum Sticking, Phys. Rev. Lett. 91, 226105 (2003).
  • D.P. Clougherty, Endohedral Impurities in Carbon Nanotubes, Phys. Rev. Lett. 90, 035507 (2003).
  • D.P. Clougherty, Ferroelectricity in (K@C60)n, in Fundamental Physics of Ferroelectrics, R. Cohen (Academic Press, NY, 2000).
  • D.P. Clougherty and F.G. Anderson, Theory of Spontaneous Polarization of Endohedral Fullerenes, Phys. Rev. Lett. 80, 3735 (1998).
  • D.P. Clougherty and X. Zhu, Stability and Teller's Theorem: Fullerenes in the March Model, Phys. Rev. A 56, 632 (1997).
  • D.P. Clougherty, On the Stability of Rare Gas Endohedral Fullerenes, Can. J. Chem. 74, 965 (1996).
  • D.P. Clougherty and J.P. Gorman, On the Low Frequency Vibrations of C60, Chem. Phys. Lett., 251, 353 (1996).
  • D.P. Clougherty and W. Kohn, Quantum Theory of Sticking, Phys. Rev. B 46, 4921 (1992).

Randall Headrick
Assistant Professor

Dr. Headrick's research is in the area of condensed matter and materials physics. Topics include the kinetics of thin film growth, and etching. He has also been active in the areas of X-ray scattering studies of materials growth and surface evolution.

Dr. Headrick received his B.S. degree in Physics from Carnegie Mellon University, and his PhD in Materials Science and Engineering from the University of Pennsylvania. He was a postdoctoral member of technical staff at AT&T Bell Laboratories, Murray Hill NJ, and a Senior Staff Scientist at the Cornell High Energy Synchrotron Source. He currently has a visiting appointment at Cornell University.

  • R.L. Headrick, I.K. Robinson, E. Vlieg, and L.C. Feldman, Structure Determination of the Si(111):B (sqrt 3 x sqrt 3) Surface: Subsurface Substitutional Doping, Phys. Rev. Lett., 63, 1253 (1989).
  • R.L. Headrick, B.E. Weir, A.F.J. Levi, D.J. Eaglesham, and L.C. Feldman, The Si(100)-(2x1) Boron Reconstruction: Self-Limiting Monolayer Doping, Appl. Phys. Lett. 57, 2779 (1990).
  • M.L. Green, B.E. Weir, D. Brasen, Y.F. Hseih, G. Higashi, A. Feygenson, L.C. Feldman, and R.L. Headrick, Mechanically and Thermally Stable Si-Ge Films and Heterojunction Bipolar Transistors Grown by RapidThermal Chemical Vapor Deposition (RTCVD) at 900°C, J. Appl. Phys. 69 (2), 745 (1991).
  • R.L. Headrick, S. Kycia, A.R. Woll, J.D. Brock, M.V. Ramana Murty, Ion-assisted nucleation and growth of GaN on Sapphire(0001), Phys. Rev. B 58, 4818 (1998).
  • A.R. Woll, R.L. Headrick, S. Kycia, and J.D. Brock, Nucleation and growth of GaN on sapphire (0001): incorporation and interlayer transport, Physical Review Letters 83, 4349 (1999).
  • M.V. Ramana Murty, T. Curcic, A. Judy, B.H. Cooper, A.R. Woll, J.D. Brock, S. Kycia, and R.L. Headrick, X-ray scattering study of the surface morphology of Au(111) during Ar+ ion irradiation, Phys. Rev. Lett 80, 4713 (1998).
  • M.L. Swiggers, G. Xia, J.D. Slinker, A.A. Gorodetsky, G.G. Malliaras, R.L. Headrick, C. Dulcey and R.N. Shashidhar, Orientation of pentacene films using surface alignment layers and its influence on thin film transistor characteristics, Applied Physics Letters, 79, 1300 (2001).
  • C.C. Umbach, R.L. Headrick, and K.-C. Chang, Spontaneous Nanoscale Corrugation of Ion-Eroded SiO2: The Role of Ion-Irradiation-Enhanced Viscous Flow, Phys. Rev. Lett., 87, 246104 (2001).

Joanna M. Rankin
Professor

Dr. Joanna Rankin carries out research in observational radio astronomy with primary interests in the areas of the pulsar radio-frequency emission problem, pulsars as probes of the interstellar medium, and feminist studies of science. During the last few years, she has published a series of papers describing a phenomenological model of pulsar emission. She regularly makes observations using the Arecibo Observatory in Puerto Rico and other instruments, and her recent observations have focused on the polarization properties of pulsar emission, both of average profiles and of trains of individual pulses. She actively collaborates with astronomers throughout the world including India and Russia and is actively interested in science as it is connected to militarism, third-world development, and women's emancipation.

Dr. Rankin has a B.S. degree in Physics and Mathematics from Southern Methodist University, an M.S. degree in Physics from Tulane University, and a Ph.D. in Astrophysics from the University of Iowa. At Iowa, she studied under Professor James A. Van Allen.

  • Toward an Empirical Theory of Pulsar Emission: VI. Geometry of the Conal Emission Region, Astrophys. J. 405, No. 1, Part 1, (1993), and The Astrophys. J. Suppl. Ser 85, (1993 March)
  • Microstructure-determined Pulsar Dispersion Measures and the Problem of Profile Alignment, with T.H. Hankins, V.A. Izvekova,
  • A.D. Kuz'min, V.M. Malofeev, and D.R. Stinebring, Astrophys. J. (Letters) 373, L17 (1991).
  • An Empirical Theory of Pulsar Emission, Texas/European Southern Observatory-CERN Conference on Relativistic Astrophysics, Brighton, U.K., December 1990.

Malcolm Sanders
Senior Lecturer

Dr. Sanders' research involves "Quantum Chaos" which can be loosely described as the quantum mechanical behavior of nonlinear systems, for example, atoms and molecules subjected to strong external electric and magnetic fields. These systems transition from regular behavior to stochastic behavior when the external perturbing fields are increased. He is also interested in national and global energy policy issues.

Dr. Sanders received a B.S. in Engineering Physics from the University of Maine, and M.S., M. Phil., and Ph.D. degrees, all from Yale University. He has held appointments at the Center for Nonlinear Studies at the Los Alamos National Laboratory, the University of Maine and Bates College.

  • M.M. Sanders and R.V. Jensen, Classical Theory of Chaotic Ionization of Rydberg Helium Atoms, American Journal of Physics, 64, No. 8, August 1996.
  • M.M. Sanders and R.V. Jensen, Classical Theory of Chaotic Ionization of Highly-excited Hydrogen Atoms, American Journal of Physics, 64, No. 1, January 1996.
  • R.V. Jensen, S.M. Susskind, and M.M. Sanders, Chaotic Ionization of Highly Excited Hydrogen Atoms: Comparison of Classical and Quantum Theory with Experiment, Physics Reports, 201 No. 1, March 1991.
  • M.M. Sanders, Energy from the Oceans, in The Energy Sourcebook: A guide to Technology, Resources, and Policy, Ruth Howes and Anthony Fainberg, Editors, AIP 1991.

David Y. Smith
Professor Emeritus

Dr. Smith's research interests lie in the area of condensed-matter, atomic and optical physics. Current research includes (a) Optical properties of matter at X-ray wavelengths, (b) Sum-rule constraints on optical properties, (c) Electron structure of solids, and (d) Defects in insulating solids.

Dr. Smith received his B.S. from Rensselaer Polytechnic Institute and his Ph. D. from the University of Rochester. He has held NSF fellowships at Princeton University and the Universität Stuttgart.

  • M.S. Malghani and D.Y. Smith, Physical Basis of the Mollwo-Ivey Relation between Lattice Constant and Optical Absorption of Defects in Ionic Crystals, Phys. Rev. Lett. 69, 184-187 (1992).
  • M.S. Malghani and D.Y. Smith, Host-Lattice Scaling of Defect Quantum States, Materials Science Forum, 239-241, 365-368 (1997).
  • D.Y. Smith and M.S. Malghani, Effective-Mass Effects on Localized Defects in Ionic Solids: Kinetic Confinement, Materials Science Forum, 239-241, 369-372 (1997).
  • D.Y. Smith and M.S. Malghani, Configuration of the Self-Trapped Exciton in the Alkali Halides, Journal of Luminescence, 72 and 74, 887-889 (1997).

Kevork Spartalian
Associate Professor

Dr. Spartalian's research is primarily in the area of magnetic measurements on biomolecules and related model complexes containing transition metal ions. Experimental data collected by Mössbauer spectroscopy, electron paramagnetic resonance, and magnetic susceptibility measurements are fitted to theoretical models with specific emphasis on the electronic structure at the metal site.

Dr. Spartalian has a B.A. degree from Princeton University and M.S. and Ph.D. degrees from Carnegie-Mellon University.

  • B.R. Serr, C.E.L. Headford, O.P. Anderson, C.M. Elliott, C.K. Schauer, K. Spartalian, V.E. Fainzilberg, W.E. Hatfield, B.R. Rohrs, S.S. Eaton and G.R. Eaton, Cytochrome c Oxidase Models: A Dinuclear Iron (III) Porphyrin-Copper(II) Complex with a Sulfur Bridge, Inorg. Chem. 31, 5450 (1992).
  • K. Kustin, W.E. Robinson, R.B. Frankel and K. Spartalian, Magnetic Properties of Tunicate Blood Cells II: Ascidia Ceratodes, J. Inorg. Biochem, 63, 223 (1996).
  • N.S. Dean, L.M. Mokry, M.R. Bond, M. Mohan, T. Otieno, C.J. O'Connor, K. Spartalian and C.J. Carrano, Vanadium Hydrobis(pyrazolyl)borate Complexes of Diphenyl Phosphate. Heterometallic Complexes of the [LV{PhO)2PO2}3]-, Fragment, Inorg. Chem. 36, 1424 (1997).

Junru Wu
Professor

Dr. Wu's research interests are concerned with nonlinear phenomena, phase transitions in condensed matter, ultrasonic and optical applications in industry and in biomedical systems. They include

(a) experimental search for localized states (solitons) in nonlinear media, (b) ultrasound sensors, (c) ultrasound heating in tissues, and (d) biomedical applications of acoustical and optical tweezers.

Dr. Wu has a B.S. in Physics from Nanjing University, China, and an M.S. and Ph.D. in Physics from the University of California at Los Angeles.

Dr. Wu has been a fellow of Acoustical Society of America since 1991 and American Institute of Ultrasound in Medicine since 1996.

  • D. Warshaw, E. Hayes, D. Gaffney, A-M. Lauzon, J. Wu, K. Trybus, S. Lowey, C. Berger, Myosin Conformational States Determined by Single Fluorophore Polarization, Proc. Natl. Acad. Sci. USA. 95, 8034-8039 (1998).
  • M. Ward, J. Wu, and J-F Chiu, Ultrasound-Induced Cell Lysis and Sonoporation Enhanced by Contrast Agents, J. Acoust. Soc. Am. 105, 2951-2957 (1999).
  • T. L. Szabo and J. Wu, A Model for Longitudinal and Shear Wave Propagation in Viscoelastic Media, J. Acoust. Soc. Am. 107, 2437-2446 (2000).
  • D. Fischer, W. Varhue, J. Wu, and C. Whiting, Lamb-Wave Microdevices Fabricated on Monolithic Single Crystal Silicon Wafers, IEEE Journal of Microelectromechanical Systems, 9, 88-93 (2000).

  • M. Ward, J. Wu and J-F Chiu, Experimental Study on Effects of Optison Concentration on sonoporation in vitro, Ultrasound in Med. & Biol 26, 1169-1175 (2000).

  • W. Chen and J. Wu, Reflectometry Using Longitudinal, shear and Rayleigh Waves, Ultrasonics 38, 909-913 (2000).

  • S. Ye, J. Wu, and J. Peach, Ultrasound Shear Wave Imaging for Bone, Ultrasound in Med. & Biol, 26, 833-837  (2000).

  • J. Wu, TOFU As A Tissue-Mimicking Material, Ultrasound in Med. & Biol 27, 1297-1300 (2001).


Jie Yang
Associate Professor

Dr. Yang's main interests concentrate on biophysics in lower dimensions. One area involves in situ high-resolution structural studies of membrane proteins using state-of-the-art atomic force microscopy, in which the goal is to fully use the power of AFM to obtain nm-resolution structure of membrane proteins. One area aims at an understanding of the 2-D condensation of DNA oncationic membranes, which may have potential impact on our understanding of the packing of genetic materials in higher organisms and in helping to find efficient means in gene delivery trials. A related area is to study the self-assembly of biomaterials under various conditions, by detecting the assembled structure at high resolution in combination with exploring the dynamic aspects and thermal equilibrium phases of these systems.

Dr. Yang has a B.S. degree in Physics from Nanjing University and M.S. and Ph.D. degrees in Physics from Princeton University. He joined the University of Vermont in 1994 from a position as Research Assistant Professor at the University of Virginia. Recent publications:

  • Zhifeng Shao, Jianxun Mou, Daniel M. Czajkowsky, Jie Yang and Jian-Yang Yuan, Biological atomic force microscopy: what is achieved and what is needed, Advances in Physics 45, 1-86 (1996).
  • Ye Fang and Jie Yang, Two-dimensional condensation of DNA molecules on cationic lipid membranes, J. Phys. Chem. 101, 441-449 (1997).
  • Ye Fang and Jie Yang, The growth of bilayer defects and the induction of interdigitated domains in the lipid-loss process of supported phospholipid bilayers, Biochim. Biophys. Acta 1324, 309-319 (1997).
  • Ye Fang and Jie Yang, Effect of Cationic Strength and Species on 2-D Condensation of DNA, J. Phys. Chem. 101, 3453-3456 (1997).
  • Ye Fang, Stephen Cheley, Hagan Bayley, and Jie Yang, The heptameric prepore of a staphyloccocal A-hemolysin mutant in lipid bilayers imaged by atomic force microscopy, Biochemistry 36, 9518-9522 (1997).
  • Sean Hand and Jie Yang, Self-assembly of lamellar structures of fatty acids complexed with surfactant in aqueous solutions Langmuir, 14, 3597-3601 (1998).
  • M. S. Malghani and Jie Yang, Stable binding of DNA to zwitterionic lipid bilayers in aqueous solutions. J. Phys. Chem. 44, 8930-8933 (1998).
  • M.S. Malghani, Ye Fang, Stephen Cheley, Hagan Bayley, and Jie Yang, Heptameric structures of two a-hemolysin mutants imaged with in situ atomic force miscopscopy. Miscoscopy Res. & Tech. 44, 353-356 (1999).
  • Jie Yang and Jennifer Appleyard The main phase transition of mica-supported phosphatidylcholine membranes. J. Phys. Chem. 104, 8097-8100 (2000).
  • Matthew Mazloff and Jie Yang Morphology and Kinematics of Langmuir-Blodgett Monolayers. Langmuir, 17, 2727-2732 (2001).
  • X.E. Cai and Jie Yang, Molecular forces for the binding and condensation of DNA molecules. Biophys. J. 82, 357-365 (2002).