Fundamental Interactions of X-rays with Atoms and Molecules; Photoionization; X-ray Emission; Molecular Photofragmentation
When a gas-phase atom or small molecule absorbs an x-ray photon with sufficient energy to excite or ionize a core electron, a multi-step decay process is initiated. The subsequent decay can include such effects as photoelectron emission, x-ray photon emission (fluorescence), and secondary-electron emission. In addition, for molecules, the resulting multiply ionized species generally fragment with a great deal of kinetic energy. The purpose of this research program is to study the many ways in which atoms and molecules dissipate the large amount of energy received via x-ray absorption, and to use this knowledge to understand electronic structure, molecular geometry, and the dynamics of the decay process. To pursue these efforts, it is necessary to use synchrotron radiation, the most intense source of x-rays known, which is produced by electrons confined to circular orbits in large electron-storage rings. Synchrotron radiation is a nearly laser-like source (collimated, pulsed, and polarized) which covers the energy range from the visible to hard x-rays. By coupling to this source electron, ion, and x-ray detectors, it is possible to distinguish decay paths following x-ray absorption. Most of the necessary equipment for this work is constructed, with the aim of using a brand new state-of-the-art synchrotron-radiation source now in operation at Lawrence Berkeley National Laboratory in Berkeley, CA.
J.C. Levin, C. Biedermann, N. Keller, L. Liljeby, R.T. Short, I.A. Sellin, and D.W. Lindle: "Photoion Auger-Electron Coincidence Measurements Near Threshold" Nucl. Instrum. Meth. B56/57, (1991).
J.C. Levin, D.W. Lindle, N. Keller, R.D. Miller, Y. Azuma, N. Berrah Mansour, H.G. Berry, and I.A. Sellin: "Double-to-Single Photoionization Ratio of Helium at 2.8 keV Using Synchrotron Radiation" Phys. Rev. Lett. 67, 968 (1991).
D.W. Lindle, P.L. Cowan, T. Jach, R.E. LaVilla, R.D. Deslattes, and R.C.C. Perera: "Polarized X-Ray Emission Studies of Methyl Chloride and the Chlorofluoromethanes" Phys. Rev. A 43, 2353 (1991).
D.W. Lindle and B. Crasemann: "Atomic, Molecular, and Optical Physics with X-Rays" Nucl. Instrum. Meth. B56/57, 441 (1991).
R. Mayer, D.W. Lindle, S.H. Southworth, and P.L. Cowan: "Direct Determination of Molecular Orbital Symmetry of H2S Using Polarized X-Ray Emission" Phys. Rev. A 43, 235 (1991).
R.C.C. Perera, P.L. Cowan, D.W. Lindle, R.E. LaVilla, T. Jach, and R.D. Deslattes: "Molecular Orbital Studies Via Satellite-Free X-Ray Fluorescence: Cl K-V Emission and K Absorption Spectra of Chlorofluoromethanes" Phys. Rev. A 43, 3609 (1991).
S.H. Southworth, D.W. Lindle, R. Mayer, and P.L. Cowan: "Anisotropy of Polarized X-Ray Emission from Atoms and Molecules" Nucl. Instrum. Meth. B56/57, 304 (1991).
S.H. Southworth, D.W. Lindle, R. Mayer, and P.L. Cowan "Anisotropy of Polarized X-Ray Emission from Molecules" Phys. Rev. Lett. 67, 1098 (1991).
L.-Q. Wang, Z. Hussain, Z.Q. Huang, A.E. Schach von Wittenau, D.W. Lindle, and D.A. Shirley: Phys. Rev. B 44, 13711 (1991).
J.C. Levin, I.A. Sellin, B.M. Johnson, D.W. Lindle, R.D. Miller, N. Berrah, Y. Azuma, B.M. Johnson, H.G. Berry, and D.-H. Lee: "High-Energy Behavior of the Double Photoionization of Helium from 2 to 12 keV" Phys. Rev. A 47, R16 (1993).
D.W. Lindle, W.L. Manner, L. Steinbeck, E. Villalobos, J.C. Levin, and I.A. Sellin "Auger Electron-Photoion Coincidence Measurements of Atoms and Molecules Using X-Ray Synchrotron Radiation" J. Electron Spectrosc. 67, 373 (1994). (Invited paper to a special issue honoring T. A. Carlson for his pioneering work in Auger spectroscopy.)
R.C.C. Perera, G. Jones, and D.W. Lindle: "High-Brightness Beamline for X-Ray Spectroscopy at the Advanced Light Source" Rev. Sci. Instrum. 66, 1745 (1995).
G. Jones, S. Ryce, D.W. Lindle, B.A. Karlin, J.C. Woicik, W. Ng, and R.C.C. Perera: "Design and Performance of the ALS Double-Crystal Monochromator" Rev. Sci. Instrum. 66, 1748 (1995).
N. Berrah, B. Langer, J. Bozek, T.W. Gorczyca, O. Hemmers, D.W. Lindle, and O. Toader: "Angular-Distribution Parameters and R-Matrix Calculations of Ar 3s-1 --->np Resonances" J. Phys. B29, 5351 (1996).
O. Hemmers, P. Glans, D.L. Hansen, H. Wang, S.B. Whitfield, D.W. Lindle, R. Wehlitz, J.C. Levin, I.A. Sellin, and R.C.C. Perera "Photoelectron Spectroscopy and the Dipole Approximation"Synch. Rad. News, Vol. 9, No. 6, 40-45 (1996). Errata Vol. 10, No. 3, 21 (1997).
W. Ng, G. Jones, R.C.C. Perera, D. Hansen, J. Daniels, O. Hemmers, P. Glans, S. Whitfield, H. Wang, and D.W. Lindle: "First Results from the High-Brightness X-Ray Spectroscopy Beamline 9.3.1 at the Advanced Light Source" Rev. Sci. Instrum. 67 (1996).
R. Wehlitz, I. A. Sellin, O. Hemmers, S. B. Whitfield, P. Glans, H. Wang, D. W. Lindle, B. Langer, N. Berrah, J. Viefhaus, and U. Becker: "Photon energy dependence of ionization-excitations in helium at medium energies" J. Phys. B 30, L51-L58 (1996).
E. W. B. Dias, H. S. Chakraborty, P. C. Deshmukh, S. T. Manson, O. Hemmers, P. Glans, D. L. Hansen, H. Wang, S. B. Whitfield, D. W. Lindle, R. Wehlitz, J. C. Levin, I. A. Sellin, and R. C. C. Perera: "Breakdown of the Independent Particle Approximation in High-Energy Photoionization" Phys. Rev. Lett. 78, 4553-4556 (1997).
D. W. Lindle, O. Hemmers, P. Glans, D. L. Hansen, H. Wang, S. B. Whitfield, R. Wehlitz, J. C. Levin, I. A. Sellin, R. C. C. Perera: "The X-Ray Atomic and Molecular Spectroscopy Program at the Advanced Light Source" Indian J. Phys. (1997) (in press).
W. C. Stolte, Y. Lu, J. A. R. Samson, O. Hemmers, D. L. Hansen, S. B. Whitfield, H. Wang, P. Glans, and D. W. Lindle: "The K-shell Auger decay of atomic oxygen" J. Phys. B 30, 4489-4497 (1997).
O. Hemmers, G. Fisher, P. Glans, D. L. Hansen, H. Wang, S. B. Whitfield, D. W. Lindle, R. Wehlitz, J. C. Levin, I. A. Sellin, R. C. C. Perera, E. W. B. Dias, H. S. Chakraborty, P. C. Deshmukh, and S. T. Manson: "Beyond the dipole approximation: angular-distribution effects in valence photoemission" J. Phys. B 30, L727-L733 (1997).
- 1997 CoSci Distinguished Research Award (UNLV)
|Title||Funding Source||S/E Dates||Amount|
|Ionization and Fragmentation Dynamics of Gases Using Hard-X- Ray Synchrotron Radiation||The Research Corporation||6/92 to 5/93||$30,000|
|Ionization and Fragmentation Dynamics of Gases Using Hard-X- Ray Synchrotron Radiation||American Chemical Society Petroleum Research Fund||9/92 to 8/94||$20,000|
|X-Ray Spectroscopy at the Advanced Light Source||Department of Energy||to construct an x-ray beamline||$1,200,000|
|Angle-Resolved Photoion-Auger-Electron Coincidence Measurements Following K-Shell Excitation by Synchrotron Radiation||Dept. of Energy Travel Grant (Brookhaven National Lab.)||1992-93||$3000|
|Ionization and Fragmentation of Small Molecules Using X Rays||UNLV University Grants and Fellowships Committee||$3000|
|Synchrotron-Radiation Endstation for Atomic and Molecular Research with X Rays at the Advanced Light Source||National Science Foundation||4/94 to 3/96||$550,000|
|Nevada DoE-EPSCoR Program: Chemical-Physics Project #2||12/94 to 12/96||$165,305|
|Ionization and Fragmentation Dynamics of Gases Using Hard-X-Ray Synchrotron Radiation||Research Corporation||6/94 to 5/96||$6,000|
|1995 Traineeship for Grad. Student D. Hansen||DOE EPSCoR||1/95-12/95||$17,000|
|Travel to the International Workshop on Soft X-Ray Fluorescence Spectroscopy||Barrick Faculty Travel Committee||3/95||$550|
|1996 Traineeship for Grad. Student D. Hansen||DOE EPSCoR||1/96-12/96||$17,000|
|'Absolute' Spectroscopies of Environment-Friendly 'Temporary' Substitutes of Chlorofluorocarbons||NATO||$7,380|
|Synchrotron Radiation Project of the Nevada Chemical Physics Cluster||DOE EPSCoR||10/96-9/97||$110,600|
|Travel to the Eleventh National Conference of the Indian Society of Atomic and Molecular Physics||Barrick Faculty Travel Committee||$700|
|State Match for DOE EPSCoR Project (FY98)||University and Community College System of Nevada||9/97-98||$10,589|
|Atomic and Molecular Research with X-Rays||National Science Foundation||9/97-8/98||$100,000|