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in subjects: "Electron Detachment"

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State-to-state photodetachment in the negative hydrogen ion

In this final report of a 3-year LDRD project on the fundamental physics of the negative hydrogen ion, new physical phenomena were observed, including the first direct excitation (i.e. without intermediate resonances) of a multiphoton electron detachment resonance in an atomic ion, and the first excess photon detachment of an electron from an atomic species in competition with a single photon process. These new phenomena are relevant to modeling and theory discrimination in 3-body quantum mecha… more

Date: August 1, 1997

Creator: Strauss, C. E.; Funk, D. J.; Zhao, X. M.; Stintz, A.; Rislove, D.; Gulley, M. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Relativistic atomic beam spectroscopy. Progress report, February 1--September 30, 1990

This year major advances have been made in 3 areas: high-lying, doubly-excited resonance states in the H{sup -}, interaction of relativistic H{sup -} ions with thin carbon foils, and multiphoton photodetachment. We plan to pursue these studies further.

Date: December 31, 1990

Creator: Bryant, H.C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Negative ion detachment cross sections. Interim progress report

During past year, we have measured cross sections for associative and collisional detachment for several negative ions in collisions with atomic hydrogen. Additional experiments have been performed in which the formation of secondary negative ions and electrons by means of low energy ion impact on surfaces has been studied. Brief descriptions of these activities along with future plans for the project follow.

Date: December 1, 1991

Creator: Champion, R. L. & Doverspike, L. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Electron energy spectra of H{sup {minus}} autodetaching states resulting from collisions of H{sup {minus}} with He at 1 keV

Electron energy spectra for H{sup {minus}} autodetaching states resulting from collisions H{sup {minus}} with He at 1 keV are rigorously calculated by including couplings between doubly excited states and continuum states and their interference with direct detachment processes. An energy sampling procedure, based on the Gauss quadratures, is used to discretize continuum states. The present theoretical result, for the first time, clarifies mechanisms of excitation to doubly excited states, quant… more

Date: June 1, 1995

Creator: Kimura, M.; Sato, H.; Hino, K. & Matsuzawa, M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Atomic physics in strong fields. Final report, September 15, 1990--August 15, 1997

In this final report the author presents a summary of recent research accomplishments. In this grant period (FY90--97), some 36 papers have been published. [See Part 4 for a list of publications]. Significant progress has been made in several areas, both in the development of new theoretical and computational methods, their applications to experimental observations, and in the prediction of some novel new high-intensity phenomena. More detailed discussions on individual research project can be … more

Date: December 1, 1997

Creator: Chu, S. I.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Collisional Cooling of Negative Ion Beams

Investigations have been conducted to determine the feasibility of using collisional cooling for reducing the energy spreads and, consequently, the emittances of negative-ion beams. We have designed a gas-filled RF-quadrupole ion cooler equipped with provisions for retarding energetic negative ion beams to energies below thresholds for electron detachment at injection and for re-acceleration to high energies after the cooling process. The device has been used to cool O{sup -} and F{sup -} ion b… more

Date: June 29, 2001

Creator: Liu, Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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A shape resonance observed in fast collisions of Li{sup {minus}} ions with gas targets

A shape resonance state in the Li{sup {minus}} ion. identified as the 2s2p {sup 3}P{sup o} state. has been populated in 100 keV collisions with a He gas target. The resonance was observed via zero-degree electron detachment spectroscopy in which kinematic shifting and doubling were exploited in the detection of the very low energy electrons. The electrons ejected via the resonance gave rise to structures in the electron energy spectra that were disposed about a continuum cusp. These structures … more

Date: December 31, 1994

Creator: Lee, D. H.; Brandon, W. D. & Pegg, D. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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An Apparatus for the Measurement of Various Scattering Processes in Intermediate Energy, Ion - Atom Collisions

This paper summarizes the main features of an apparatus constructed at the University of Toledo for the study of various scattering processes in intermediate energy, ion - atom collisions. The main purpose of this facility is to provide experimental data which serve as benchmarks to test current scattering theories for those processes. Recent measurements of single electron detachment (SED) and double electron detachment (DED) total cross sections for 5-50 keV H{sup -} ions incident on noble ga… more

Date: July 1, 1998

Creator: Kvale, T. J. & Seely, D. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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The production and destruction of negative ions. Progress report, September 1, 1996--August 31, 1997

During the grant period, 1994--97, the author continued to investigate the structure of few-electron atomic negative ions and the manner in which they interact with electromagnetic radiation. The experimental procedures and the results of this work have been described in detail in the published papers cited in Section G. Two complementary laser-ion beam apparatus were used in the measurements. A crossed beam apparatus, situated at Oak Ridge National Laboratory (ORNL), was used to perform a spec… more

Date: December 31, 1997

Creator: Pegg, D. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Effect of temperature on the electron attachment and detachment properties of c-C{sub 4}F{sub 6}

The temperature dependence of the low-energy electron attachment and autodetachment processes for c-C{sub 4}F{sub 6} in a N{sub 2} buffer gas has been studied in the temperature, T, range of 300 to 600 K and the mean electron energy, <{epsilon}>, range from 0.19 to 1.0 eV. The low-energy electron attachment rate constant for c-C{sub 4}F{sub 6} shows only a slight dependence on gas temperature. In contrast, the autodetachment frequency increases by more than four orders of magnitude when T is in… more

Date: June 1, 1994

Creator: Datskos, P. G.; Christophorou, L. G. & Carter, J. G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Studies of clusters. Fourth quarterly technical progress report, April 1, 1993--June 30, 1993

Positive cluster ions were produced, and the mass spectrum was measured using a radiofrequency quadrupole mass spectrometer. Mass spectra are attached, showing the cluster ions produced using pure ammonia. They have the general formula (NH {sub 3}){sub n}H {sub m}{sup +}, where n and m are integers. Peaks with different numbers of hydrogens can barely be resolved. This shows that the ion source can produce cluster ions. The development of sensitive laser techniques is necessary for probing the … more

Date: August 1, 1993

Creator: Farley, J. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Relativistic atomic beam spectroscopy II

The negative ion of H is one of the simplest 3-body atomic systems. The techniques we have developed for experimental study of atoms moving near speed of light have been productive. This proposal request continuing support for experimental studies of the H{sup -} system, principally at the 800 MeV linear accelerator (LAMPF) at Los Alamos. Four experiments are currently planned: photodetachment of H{sup -} near threshold in electric field, interaction of relativistic H{sup -} ions with matter, h… more

Date: December 31, 1989

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Relativistic atomic beam spectroscopy. Progress report, July 20, 1987--June 30, 1989

With the HIRAB (High Resolution Atomic Beam) building, the photodetachment experiments at LAMPF was able to continue. The 1988 runs provided data to complement that of 1986 on effects of electric fields on photodetachment cross section of H{sup -} and interaction of thin foils with relativistic H{sup -} ions. The first multiphoton detachment of H{sup -} was observed. In each of these experiments, a high-powered laser beam was allowed to intersect the relativistic ion beam; the photon energy in … more

Date: June 1, 1989

Creator: Bryant, H. C.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurements of scattering processes in negative ion - atom collisions. Technical progress report - year 1, April 1, 1995--March 31, 1996

This Technical Progress Report describes the progress made on the research objectives during the past twelve months. The objective of this research project is to provide absolute cross section measurements of various scattering processes which occur in negative ion collisions with atomic (specifically, noble gas and atomic hydrogen) targets at intermediate energies. These processes include: elastic scattering, single- and double-electron detachment, and target-inelastic processes of excitation … more

Date: December 1, 1995

Creator: Kvale, T.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Negative ion collisions. Progress report, April 1, 1994--March 31, 1997

During the last three years, the experimental activities have concentrated on several somewhat distinct projects. First, the author has measured total cross sections for electron detachment and charge transfer for collisions of various negative ions with atomic hydrogen and the molecular target, O{sub 3} (ozone). The second type of gas phase experiments investigated the collisional decomposition of the molecular ion H{sub 3}{sup +}. Specifically he has measured total cross sections for dissocia… more

Date: August 1, 1996

Creator: Champion, R. L.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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The production and destruction of negative ions. Progress report, September 1, 1992--August 31, 1993

Single photon absorption-single electron detachment from few-electron atomic negative ions was studied. A crossed beam apparatus is being used to perform energy- and angle-resolved photoelectron spectroscopic measurements following photodetachment. Forward-directed electrons were collected and energy analyzed. The kinetic energies and yields of the photoelectrons were obtained by fitting the spectral peaks to Gaussian functions. Electron affinities, asymmetry parameters and cross sections are d… more

Date: April 1, 1993

Creator: Pegg, D. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurements of scattering processes in negative ion-atom collisions. Technical progress report, 1 September 1991--31 August 1992

This Technical Progress Report describes the progress made on the research objectives during the past twelve months. This research project is designed to provide measurements of various scattering processes which occur in H{sup {minus}} collisions with atomic (specifically, noble gas and atomic hydrogen) targets at intermediate energies. These processes include: elastic scattering,single- and double-electron detachment, and target excitation/ionization. For the elastic and target inelastic proc… more

Date: April 1, 1992

Creator: Kvale, T. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Measurements of scattering processes in negative ion: Atom collisions. Technical progress report, 1 September 1991--31 December 1994

This report describes the progress made on the research objectives during the past three years of the grant. This research project is designed to study various scattering processes which occur in H{sup {minus}} collisions with atomic (specifically, noble gas and atomic hydrogen) targets in the intermediate energy region. These processes include: elastic scattering, single- and double-electron detachment, and target excitation/ionization. For the elastic and target inelastic processes where H{su… more

Date: September 27, 1994

Creator: Kvale, T. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Atomic negative ions

We review some of the recent progress in the studies of alkaline-earth, negative ions. Computations of autodetachment rates, electron affinities and transition wavelengths are discussed and some new and improved results are given.

Date: December 31, 1991

Creator: Brage, T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Dynamics of collision processes. Progress report, September 1, 1991--July 31, 1994

Investigations have been carried out of one-, two-, and three-photon detachment of the negative hydrogen ion (H{sup -}) including effects of electron correlations, of two-color detachment of H{sup -} with excitation of H(n=2), and of the {sup 3pe} state of H{sup -}. Striking effects of long-range dipole field interactions have been demonstrated. Electron correlation effects on detachment cross sections have been quantified. Electric field effects on photodetachment of H{sup -} above the H(n=2) … more

Date: February 1, 1994

Creator: Starace, A. F.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O{sub 3}{sup {minus}}. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO{sub 2}, has been investigated, providing vibrational frequencies and e… more

Date: August 1, 1994

Creator: Arnold, D. W.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

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2001 Gordon Research Conference on Photoions, Photoionization and Photodetachment. Final progress report [agenda and attendees list]

The Gordon Research Conference on Photoions, Photoionization and Photodetachment was held at Williams College, Williamstown, Massachusetts, July 8-13, 2001. The 72 conference attendees represented the spectrum of endeavor in this field, coming from academia, industry, and government laboratories, and including US and foreign scientists, senior researchers, young investigators, and students. Emphasis was placed on current unpublished research and discussion of the future target areas in this fie… more

Date: July 13, 2001

Creator: Johnson, Mark

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Photodetachment studies on few-electron atomic negative ions

A crossed laser-negative ion beams apparatus, situated at Oak Ridge National Laboratory has been used for energy and angle-resolved photoelectron spectroscopic measurements following photodetachment. In the current grant period measurements of the cross sections for photodetaching an electron from the Li{sup {minus}} ion were finished. Measurements of the {sigma}(B{sup {minus}})/{sigma}(Li{sup {minus}}) ratio, with a goal of determining photodetachment cross section for B{sup {minus}}, were sta… more

Date: December 31, 1992

Creator: Pegg, D. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Photodetachment cross sections for He/sup -/(/sup 4/P/sup 0/)

The first measurements are reported of photodetachment cross sections for He/sup -/ (formed through charge exchange of He/sup +/ with Ca vapor) over the photon energy range from 1.77 to 2.75 eV. The energies of autodetached electrons from the metastable He/sup -/ beam have also been determined for the first time. The autodetached electron energy agrees within experimental error (+-0.25 eV) with the known 1s2s2p)/sup 4/P/sup 0/ He/sup -/ energy level. This taken with measurements for the lifetim… more

Date: January 1, 1980

Creator: Compton, R. N.; Alton, G. D. & Pegg, D. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department