Negative ion physics
My research interests lie in the area of accelerator-based atomic physics with particular emphasis on the structure of negative ions and the manner in which they interact with electromagnetic radiation and other particles. The primary objective of the research is to develop a better understanding of the fundamental problem of correlated electron motion in few-electron systems. The backbone of our knowledge of multi-electron atomic systems is the independent electron model. Correlation effects, which are particularly enhanced in loosely bound systems such as negative ions, lead to a breakdown of the independent electron approximation, and the onset of collective motion.
Currently the research is performed at three sites: the Oak Ridge National Laboratory, the Department of Physics at Chalmers University of Technology in Gothenburg, Sweden, and the Manne Siegbahn Institute in Stockholm, Sweden.
In Sweden I continue to enjoy a fruitful collaboration with the research group of Professor Dag Hanstorp. We study photon-induced detachment of negative ions in the ultraviolet using a merged laser-ion beam apparatus at Chalmers University of Technology. At the Manne Seigbahn Institute in Stockholm we use the heavy ion storage ring, CRYRING, to investigate electron impact-induced detachment and dissociation of atomic, molecular and cluster negative ions. In the US I am a member of a group of researchers who use the third-generation synchrotron radiation source called the Advanced Light Source (ALS) situated at the Lawrence Berkeley National Laboratory. At this facility we use a high brightness undulator beam line to obtain a beam of soft x-ray photons. Photon-induced detachment processes involving inner-shell electrons are investigated by merging the photon beam with a negative ion beam from a small accelerator.
David J. Pegg, Professor of Physics, completed his B. Sc. degree in Physics at Manchester University in England in 1963. In 1968 and 1970 he received a M.S. and Ph.D., respectively, from the University of New Hampshire. He joined the UT Physics Department faculty in 1971 and attained the rank of full professor in 1980. In 1978 he had a 6 month research position at the University of Lund in Sweden. In 1979 he held a similar position at the University of Lyons in France. In 1997 he held a research position at Chalmers University of Technology in Gothenburg, Sweden. The leave was partially funded by an award from the Nobel Institute of the Royal Swedish Academy of Sciences. He is currently the principal investigator for a group that uses the Advanced Light Source at the Lawrence Berkeley National Laboratory. He is a Fellow of the American Physical Society and a consulting editor for the McGraw-Hill Encyclopedia of Science and Technology.
- "Cross section for the photodetachment of Be-," D.J. Pegg, C.Y. Tang, J. R. Wood, J. Dellwo and G. D. Alton, Phys. Rev. A50, 3861 (1994).
- "Photodetachment cross sections for B-," D. H. Lee, C. Y. Tang, D. J. Pegg, Y. Liu, J. Dellwo and G. D. Alton, Phys. Rev. A51, 4284 (1995).
- "Resonance structure in the Li- photodetachment cross section," U. Berzinhs, G. Haeffler, D. Hanstorp, A. Klinkmueller, E. Lindroth, U. Ljungblad and D. J. Pegg, Phys. Rev. Lett. 74, 4795 (1995).
- "New resonance states in Li- and B-," D. H. Lee, W. D. Brandon, D. Hanstorp and D. J. Pegg, Phys. Rev A53, R633 (1996).
- "Photodetachment of C-, "W. D. Brandon, D. H. Lee, D. Hanstorp and D. J. Pegg, J. Phys. B. 31, 251 (1998).
- "Cross section for photodetachment of the excited C- ion," D. H. Lee, W. D. Brandon, D. J. Pegg and D. Hanstorp, Phys. Rev. A56, 1346 (1997).
- "Observation of doubly excited states of Li-," U. Ljungblad, D. Hanstorp, U. Berzinhs and D. J. Pegg, Phys. Rev. Lett. 77, 3751 (1996).
- "Electron affinity of Li," G. Haeffler, D. Hanstorp, I. Kiyan, A. Klinkmueller, U. Ljungblad and D. J. Pegg, Phys. Rev. A53, 4127 (1996).
- "Photodetachment study of the 1s3s4s 4S resonance in He-," A. Klinkmueller, G. Haeffler, D. Hanstorp, I. Kiyan, U. Berzinhs, C. Ingram, D. J. Pegg and J. Peterson, Phys. Rev. A56, 2788 (1997).
- "Resonance structure in the Li(4s) + e-(ep) partial photodetachment cross section," G. Haeffler, I. Kiyan, D. Hanstorp, D. J. Pegg, Phys. Rev. A57, 2215 (1998).
- "Observation of Resonance Structure in the Na- Photodetachment Cross Section" G. Haeffler, I. Kiyan, D. Hanstorp, B. Davies, D. J. Pegg, Phys. Rev. A59, 3655 (1999).
- "Photodetachment of Ca- at the 3Pkp Threshold" D. H. Lee, M.B. Poston, D. J. Pegg, D. Hanstorp, U. Berzinsh, Phys. Rev. A60, 715 (1999).
- "A Measurement of the Electron Affinity of K" K. Andersson, J. Sandstrom, I. Kiyan, D. Hanstorp, D. J. Pegg, Phys. Rev. A62, 022503-1 (2000).
- "Spectrum of Doubly-Excited States of K-" I. Kiyan, U. Berzinsh, J. Sandstrom, D. Hanstorp, D. J. Pegg Phys. Rev. Lett. 84, 5979 (2000).
- "Photodetachment Spectrum of Strongly Correlated States in the Li- ion," G. Haeffler, I. Kiyan, U. Berzinsh, D. Hanstorp, E. Lindroth and D. J. Pegg, Phys. Rev. A, 63, 053409-1 (2001).
- "The Physics of Negative Ions," D. J. Pegg, D. H. Lee and D. Hanstorp, in Atoms and Molecules in a New Light, Proceedings of the Pan-American School on Atomic, Molecular and Optical Physics, 2001.
- "Electron Detachment and Dissociation of CN-," A. Le Padellac, K. Andersson, D. Hanstorp, F. Hellberg, M. Larsson, A. Neau, S. Rosen, H. Schmidt, R. Thomas, J. Semaniak, D. J. Pegg, F. Osterdahl, H. Danered and A. Kaellberg, Physica Scripta, 64, 467 (2001).
- "Electron Impact Detachment and Dissocation of C4- Clusters," A. Le Padellac, D. J. Pegg, F. Rabilloud, A. Neau, F. Hellberg, R. Thomas, H. T. Schmidt, M. Larsson, K. Andersson, F. Sterdahl, H. Danered, A. Kaellberg and D. Hanstorp, J. Chem. Phys, 115, 10671 (2001).
- "Correlated Processes in Inner-Shell Photodetachment of the Na- Ion," A. M. Covington, A. Aguillar, V. Davis, I. Alvarez, H.C. Bryant, C. Cisneros, M. Halka, D. Hanstorp, G. Hinjosa, A. S. Schlachter, J. S. Thompson and D. J. Pegg, J. Phys. B34, L735 (2001).