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Physics Department Personnel
 Dr.
Krzysztof Kempa
Professor of Physics
617-552-3592
Higgins Hall 230E
kempa@bc.edu
Education
- Ph.D., Theoretical Physics, University of Wroclaw, Poland, 1980
- MS., Electrical Engineering: Semiconductor Technology, Technical University
of Wroclaw, Poland, 1973
Areas of Research
My research is focused on nanostructures.
Nanostructures are artificially grown or self assembled structures, with
dimensions ranging from 1 to 100 nm. In these systems cross-dimensional
behavior, as well as, crossover from quantum to classic phenomena, can
be observed. Examples include semiconductor
quantum structures (wells, wires and dots), carbon nano-materials
(carbon nanotubes,
bucky balls), and bio-molecules (DNA). Understanding of their rich physical
and chemical properties may lead, through nanotechnology,
to fascinating applications, and may also contribute to fundamental understanding
of biological processes. I am trying to understand such systems by utilizing
various theoretical schemes, including computer simulations and
modeling. This funded work is done in collaboration with students, other
theorists and experimentalists. Details below.
Research
-
Discrete optics.
We have proposed a new field of optics, based on nanoantennas and nanocoaxial
lines. These are metallic nanostructures which behave exactly like their
radio technology counterparts: they can receive light, and transmit it
through subwavelength channels. New effective media can be made based
on these nanostructures, capable of various effects: negative refraction,
subwave image resolution, wave conjugation, etc. Novel, high efficiency
and low cost solar cells can be made using these media.
- Photonic, polaritonic and plasmonic crystals.
We study properties of photonic, polaritonic and plasmonic crystals.
These are periodic dielectric and/or metallic systems, in which photon,
polariton or plasmon propagation is similar to electronic propagation
in conventional crystals. In particular, formation of a band structure,
analogous to that in solid state systems occurs. We have recently discovered
the light flux switching in such crystals, which can be used in optoelectronic
switches and bio-sensors. This research is relevant for many opto-electronic
applications. Work is being done in collaboration with Z. Ren, and part
of it is supported by grant from US Army Natick Soldier Center and NanoLab.
- Carrier dynamics.
We study interaction of electrons (or holes) with other quasiparticles
(electrons, holes, phonons, etc.), and with an electromagnetic radiation.
We also study electromagnetic emission (including lasing) in current driven
systems with strong electron-electron and electron-phonon interactions,
in particular in the terahertz (THz) frequency range. In this context
we study the possibility of a stimulated emission of plasmons (plasmon
instability). This work has been done in collaboration with P. Bakshi,
group of E. Gornik, and has been supported by a series of grants from
US Army Research Office.
- Composite nanomaterials.
By suspending nanostructures (such as carbon nanotubes) in a polymer
or ceramic matrix, novel composite materials with unique mechanical and
dielectric properties can be engineered. We study the correlation of properties
of such materials with their nano-structure. Work is being done in collaboration
with Z. Ren and supported by NanoLab.
- Bio applications of nanostructures.
We have recently demonstrated that magnetically driven carbon nanotubes
can be used as nano-vehicles capable of delivering bio-molecules to cells,
at very high efficiency. We have also demonstrated that the conventional
electroporation can be made be use of microwaves. This work has been done
in collaboration with T. Chiles (BC Biology) and NanoLab.
Other Activity
Selected Publications
- J. Y. Huang, S. Chen, Z.Q. Wang, K. Kempa, Y. M. Wang, S. H. Jo,
G. Chen, M.S. Dresselhaus, and Z. F. Ren, “Superplastic single-walled
carbon nanotubes,” accepted in Nature Materials.
- K. Kempa, R. Ruppin, and J. B. Pendry, “Electromagnetic response
of a point-dipole crystal”, Phys. Rev. B 72,
205103 (2005); also featured in the November 14, 2005 issue of Virtual
Journal of Nanoscale Science & Technology.
- T. Kempa, D. Carnahan, M. Olek, M. Correa, M. Giersig, M. Cross,
G. Benham, M. Sennett, Z.F. Ren, and K. Kempa, “Dielectric Media
Based on Isolated Metallic Nanostructures,” Journal of Applied
Physics 98, 034310 (2005). The paper was selected
for the August 22, 2005 issue of Virtual Journal of Nanoscale Science
& Technology.
- D. Cai, J. Mataraza, Z. H. Qin, Z. Huang, J. Huang, T. C. Chiles,
D. Carnahan, K. Kempa, Z.F. Ren, “Highly efficient molecular delivery
into mammalian cells using carbon nanotube spearing,” Nature
Methods, vol. 2, no. 6, 449 (June 2005).
- X. Wang and K. Kempa, “Negative Refraction and Subwavelength
Lensing in a Polaritonic Crystal,” Phys. Rev. B
71, 233101 (2005).
- Y. Wang, K. Kempa, B. Kimball, J. B. Carlson, G. Benham, W. Z. Li,
T. Kempa, J. Rybczynski, A. Herczynski, and Z. F. Ren, “Receiving
and Transmitting Light like Radio Waves: Antenna Effect in Arrays of
Aligned Carbon Nanotubes,” Applied Physics Letters 85,
2607(2004). Reported in Nature and Science News, AIP, CNN and ABC
and more.
- K. Kempa, Y. Zhou, J. R. Engelbrecht, P. Bakshi, H. I. Ha, J. Moser,
M.J. Naughton, J. Ulrich, G. Strasser, E. Gornik, and K. Unterrainer
"Intersubband transport in quantum wells in strong magnetic fields
mediated by single- and two-electron scattering," Physical
Review Letters 88, 226803, (2002).
- K. Kempa, E. Gornik, K. Unterrainer, M. Kast, and G. Strasser, "Resonant
Tunneling Mediated by Resonant Emission of Intersubband Plasmons,"
Physical Review Letters 86, 2850, (2001).
- H.H. Weitering, X. Shi, P.D. Johnson, J. Chen, N.J. DiNardo, K. Kempa,
"Mott insulating ground state on a triangular surface lattice,"
Physical Review Letters 78, 1331 (1997).
- Y. Zhao, D.C. Tsui, M. Santos, M. Shayegan, R.A. Ghanbari, D.a. Antoniadis,
H. I . Smith, and K. Kempa, "Mode softening in the far-infrared
excitation of quantum-wire arrays," Physical Review B
48, 5249 (1993).
- K.D. Tsuei, E.W. Plummer, A. Liebsch, K. Kempa, P. Bakshi, "Multipole
plasmon modes at a metal surface," Physical Review Letters
64 , p. 44 (1990).
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