Experimental Research Groups

The experimental physics program at URI covers areas of biological physics, optics and spectroscopy, nanotechnology, cold neutron physics, low temperature atomic clusters, structure of surfaces and interfaces, growth of epitaxial films, magnetic nanoparticles and surfaces, x-ray diffraction, neutron diffraction, and photoemission spectroscopy.

We believe that a core component in the graduate education in experimental physics is to provide students with a supportive environment in which they, after initial training, are able to find their own initiatives in pursuit of research interests, and eventually become the primary experts in their respective fields. Most of the experiments in our research are performed in laboratories on campus, where each research student takes the responsibility for a project and apparatus under the guidance of a member of the physics faculty. Some of the experiments are performed at other national and international user facilities through multi-institutional collaboration. These collaborations are of small scale involving two or three groups, and students participating in these experiments also acquire first hand expertise, much the same way as in campus laboratories.

Many of the physics faculty are also members of the Sensors & Surface Technology Partnership, which is an interdisciplinary materials research consortium at the university, in partnership with departments of electrical engineering, chemical engineering, mechanical engineering, food science and nutrition, and chemistry, as well as with local and national industrial sponsors.

Prof. David Heskett works in experimental condensed matter physics, specializing in the physics of surfaces and thin films. He conducts experimental investigations of the electronic, structural, and dynamic properties of clean and adsorbate-covered metal and semiconductor surfaces and thin films using a variety of surface probes. Experimental techniques include X-ray Standing Waves (XSW), Angle-Resolved Ultraviolet Photoemission Spectroscopy (ARUPS), Inverse Photoemission Spectroscopy (IPES), High Resolution Core Level Spectroscopy (HRCLS), Auger Electron Spectroscopy (AES), Low Energy Electron Diffraction (LEED), Atomic Force Microscopy (AFM), and Rutherford BackScattering Spectrometry (RBS). Prof. Heskett is also interested in electromigration in aluminum alloy interconnects.

Prof. Jan Northby works in experimental low-temperature physics, studying beams of superfluid helium nanodroplets. The primary motivation is to learn about the effect of finite size on superfluidity. In order to study such a weakly interacting system it is necessary to create or attach a probe particle of some sort. His research program has centered on those particles created in clusters by electron bombardment. Most recently, the group has been studying the spectroscopy of metastable helium molecules attached to the surface of helium nanodroplets. The study exploits a new kind of laser spectroscopy in which absorption of a photon leads to the detachment of a metastable particle from the surface. In addition to studying the spectral modifications induced by the particle-surface interaction, the high detectability of such particles permits measurements of their recoil momentum. This in turn provides additional insight into their dynamical interaction with the nanodroplet.

Other experimental projects underway in Prof. Northby's laboratory include the development of beam sources of metastable helium molecules, and the development of a laser based sediment velocimeter that can be used to study sediment concentration and motion in natural waters. ( Sketch of Helium Cluster Beam Apparatus ).

Prof. Tony Nunes works in experimental condensed matter physics and neutron physics, specializing in the fields of neutron scattering and x-ray scattering. Prof. Nunes is a former student of Prof. Clifford G. Shull of MIT who was awarded the 1994 Nobel Prize in physics for his pioneering development of neutron diffraction physics. Neutron diffraction provides an indispensible probe of condensed matter. Prof. Nunes studies magnetism in nanoparticles and surfaces. Particles (a few nanometers in diameter) of some ferrites seem to have a magnetically anomalous surface layer about a nanometer thick. This layer also appears to be characterized by significant relaxation (expansion) arising from the different termination properties of the long range coulombic attractions and the short range repulsion between ions. This and the magnetoelasticity of the lattice may, at least in part, account for the magnetic anomaly.

Prof. Suren Malik and Prof. Albert Steyerl work in experimental neutron physics with main interests in ultra-cold neutrons (UCN) and neutron optics. They are collaborating with physicists at Kyushu University (Japan), the Institut Laue-Langevin, Grenoble (France), and Harvard University in studies of the properties of ultracold neutrons. These neutrons have energies of 10^-7 eV or less and are totally reflected for any angle of incidence on a wall made of a suitable material. Due to this property, the UCN can be stored in special UCN traps for hundreds of seconds.

Prof. Steyerl's research is focused on the details of the UCN-wall interaction and specifically on the question why the measured storage losses always seem to exceed the theoretical values. Very long storage lifetimes are required for applications of UCN in precise measurements of the neutron lifetime for beta-decay and in sensitive searches for an electric dipole moment of the neutron. Both of these quantities are of fundamental importance in theories of elementary particles and of cosmology. Experiments are performed at the UCN Source of the High-Flux Research Reactor of the Institut Laue-Langevin, Grenoble, France.

Professors Yana Reshetnyak and Oleg Andreev carry out research projects in various fields of experimental physics:

• Biological Physics
  • thermodynamics and kinetics of folding of membrane proteins
  • molecular mechanism of muscle contraction
  • protein fluorescence: novel mathematical algorithms of spectra analysis and application of the computational/statistical approaches for the correlation of protein spectral and structural properties
• Medical physics/Nanotechnology:
  • development of novel nanotechnology delivery platform for the selective targeting of diseased tissue for diagnostic and treatment
  • whole-body imaging, gene therapy, hyperthermia of cancer induced by illumination of carbon nanotubes etc
• Nanotechnology and optics:
  • fabrication of semiconductor nanowires using biological molecules as a template, studies of their optical and electrical properties

Links to these project can be found on the web pages of professors Reshetnyak and Andreev; or here.