Experimental atomic physics

The experimental atomic, molecular and optical physics group is involved in a diverse program that investigates the interaction of highly-charged ions with various target media. The ions are created as beams by several ion sources and accelerators located in the J. R. Macdonald Laboratory for atomic physics. The ion beams used in the experiments have a well-defined charge and energy and are thus ideally suited to investigating the behavior of collisions under a variety of well-defined conditions. Single- and multi-electron atomic and molecular processes are investigated by observing the final ionic species and their decay products. The targets in these collisions consist of ground state and laserexcited atoms and molecules, as well as atomic and molecular ion beams. Many measurements are precise enough to provide information about the specific quantum mechanical states involved in the reaction. The results of these observations are compared to the theoretical predictions made by the Kansas-State theory group as well as by theorists elsewhere. The close interplay between theorists and experimentalists often leads to a better understanding of the physics and in some cases suggests new phenomena, experimental methods, or improved calculation methods. The combination of strong groups in both theory and experiment within the same department makes Kansas State one of the leading atomic physics groups in the world. Because of this, we have attracted researchers from around the world to come to Kansas State to carry out their experiments.

A new ultra-short pulse, ultra-high intensity laser system is being used to study the interaction of the laser light with atoms, ions and molecules. High harmonic generation, ionization, electron re-scattering and molecular breakup are a few of the problems being investigated. The theorists are working in close collaboration with the experimentalists in these endeavors.

Experimental condensed matter physics

The experimental condensed matter group at K-State is conducting research in a wide range of often inter-related areas.

Research on condensed phases include the physics of aggregates, their optics (scattering and absorption), morphology, how they form and how they move; particularly in the context of aerosols, synthesis and properties (magnetic and optical) of nanoparticles and their assemblies (such as superlattices and gels) and of water, especially supercooled, and aqueous solutions.

Phase transitions at liquid surfaces and within multilayer liquid films are being studied via optical techniques in order to better understand the physics at the boundaries of bulk materials. Surface structure is strongly influenced not only by the interactions at interfaces but also by any phenomena which is occurring in the adjacent bulk medium. We have therefore been studying (i) the coupling between bulk second order phase transitions and surface phenomena where we have observed  universal surface critical behavior in both semi-infinite systems and within thin films and (ii) surface interactions and how these influence and govern surface phase transitions and surface dynamics on a molecular level. A more complete understanding of surface phenomena will be of benefit for many important technological and biological processes, such as, surface chemical reactions, lubrication, and fluid flow through biological membranes or porous media.

Magnetic nanostructures such as nanoscale particles, single layers and multilayers containing rareearths are prepared by sputter deposition. Making materials small modifies their properties in a number of interesting ways and in this work we look at how the properties of permanent magnets based on Nd2Fe14B and SmCo5 are modified. Magnetic properties down to 5 K are studied in fields up to 55 kOe and the structure of the materials is characterized with x-ray diffraction and electron microscopy. Our effort can be divided into two areas: 1) improving the hard magnetic properties of permanent  magnets (coercivity, energy product) by preparing these materials in very small form, 2) understanding how the observed improvements can be explained in terms of size and interfacial effects.

Experimental high energy physics

The High Energy Physics group has strong research programs in collider physics. Kansas State physicists are playing a key role in building the silicon vertex detector for the next upgrade of the D0 experiment at Fermilab, and are now analyzing data from the frontier of high energy proton-antiproton collisions from the previous D0 experiment. To remain at the energy frontier, they are also heavily involved in preparations for the CMS experiment now under construction at CERN.

The High Energy Physics group is also strong in neutrino physics. K-State physicists have major roles in data analysis and Monte Carlo simulation for the KamLAND experiment and the proposed Double CHOOZ and Braidwood experiments. HEP group members are leaders in the background working group of Braidwood and the on-line group of Double CHOOZ, and have initiated several local research projects to advance the future development of Braidwood, Double CHOOZ, and KamLAND.

Theoretical and computational physics

The department offers a diversified program in theoretical and computational physics, including atomic, solid state, soft condensed matter, molecular and surface physics, statistical mechanics, materials physics, cosmology and particle astrophysics. There is significant interaction between experimentalists and theorists within the department and there is also collaboration with faculty in chemistry, biochemistry and engineering. Seminars are held weekly in several of these areas.

Computational physics students are trained to solve accurately and efficiently problems in physics using a wide range of computational techniques. An important aspect of the training is the presentation of problem solutions in a way that can be easily visualized and understood. Various algorithms for molecular dynamics simulation, Monte Carlo methods, ab-initio electronic structure calculations and solutions of generalized Langevin equations are being developed. A strong focus in this area is in the development of efficient algorithms to best exploit the benefits of parallel architecture in modern computers.

A broad range of computational facilities is available in our department with the main computations being carried out using the departmental cluster of Compaq Alpha workstations, high-end and low-end Unix and Linux workstations, and the high performance computational environment provided by clusters of Linux computers. A number of faculty members and their students use supercomputers at national centers in their work, in addition to facilities housed on our own campus.

Some studies of mathematical methods in physics have also been carried out by our faculty and graduate students. These include: studies in group theory with application to atoms, molecules, and nuclei; development of the method of hyperspherical coordinates; and development of complex integration with application to Coulomb wavefunctions. Mathematical aspects of formulations of the fewbody and many-body problem have also been developed in our department.

There is strong national and international collaboration with other colleagues. We have a steady exchange with scientists in Argentina, Brazil, China, Denmark, England, France, Finland, Germany, India, Italy, Japan, Korea, Pakistan, Portugal, Spain, Sweden, and Taiwan. We participate actively in conferences ranging from regional to international. Professors, graduate students and post-doctoral fellows all take part in these meetings.

Theoretical atomic and molecular physics

A broad range of topics in both scattering theory and atomic and molecular structure are studied. These studies are often initially motivated by the need to understand experimental results; they provide broader perspectives on electronic interactions in atoms that are then further tested in experiments. To complement this focus on experimentally driven results, investigations of a fundamentally theoretical nature are also carried out including the development of novel theoretical and computational methods. Theoretical models for collisions of ions, electrons, and photons with atoms and molecules over a broad range of energies are being developed to understand the transfer of energy and momentum among the collision partners. These studies are developed to understand the results of experiments performed at Kansas State and at other laboratories. The study of atomic structure covers a detailed mapping of the de-excitation of atoms and ions produced in such collisions. Our studies of multiply excited states of atoms using hyperspherical coordinates are revealing the similarity between the collective electronic excitations of atoms and the rotational-vibrational modes of polyatomic molecules. Our investigations of interactions of ions (atoms) with surfaces and clusters (such as C60) contribute to a better understanding of corrosion, catalysis, and the still new field of fullerene chemistry.

Theoretical condensed matter physics

The Theoretical Condensed Matter Physics group works in a number of related areas, trying to understand structural, physical, chemical, electronic, vibrational, magnetic, optical, and other properties of solids and condensed phases. The types of systems studied include polymer mixtures and block copolymers, polymer films on rough substrates, metals and semiconductors and their alloys, surfaces, nanocrystallites and nanostructures, chemisorbed gases, magnetic layers, and fine magnetic particles. Theorists working in condensed matter theory apply quantum mechanics, statistical mechanics and advanced computational techniques such as ab-initio electronic structure calculations and classical and quantum Monte Carlo and molecular dynamics simulations, to model the fundamental interactions between atoms and molecules in a material. All of our theorists use computation as an important tool. In addition to achieving a basic theoretical understanding of how atomic interactions lead to interesting macroscopic behavior, an important goal of our condensed matter theorists is to describe many phenomena of technological importance, such as corrosion, catalysis, wetting, phase changes, magnetic and electronic data storage, and friction and nanotribology. Ultimately, theory developed in collaboration with experimentalists will contribute towards the development of novel materials and new and interesting devices based on those materials.

Cosmology and particle astrophysics

The cosmology research program spans both theoretical work and analyses of cosmological data. On the theoretical side we work on developing models for the large-scale matter and radiation distributions in the Universe. We study observational consequences of Dark Energy and gravity models and test them by comparing their predictions with observational data, including the anisotropy in the cosmic microwave background radiation, and the mass correlation function.

Physics education

The Physics Education Research Group at K-State investigates the learning and teaching of physics using methods drawn from physics education research, the learning sciences, and science education. The group applies evidence from research to develop ways to improve physics learning. In recent years the work of this group has concentrated research on how students learn physics and mathematics, how they come to think as physicists, and ways to make this and other research available to physics instructors at all levels. Further efforts have involved the development of learning materials for the high school and college level and the training and support of science teachers and physics faculty members through both in-person and online resources.