SRC Users' Meeting - Synchrotron Radiation Center - University of ...

More documents

Recommendations

Info

CHARACTERIZATION OF SULPHATE INTERACTIONS WITH HEMATITE MINERALS USING XANES T.Kotzer 1 , J.Cutler 1 , A.Pratt 2 , J.Dutrizac 2 1 Canadian Light Source, University of Saskatchewan, Saskatoon, Canada 2 Natural Resources Canada - CANMET, Ottawa, Canada Sulphur bearing hematite is a product of some novel hydrometallurgical sphalerite treatments. Leaching tests aimed at investigating the stability of the hematitic leach residue have shown that only a fraction of the sulphur present is removed. In this study sulphur bearing hematites were leached in a variety of media and examined using XANES Sulphur K-edge and L-edge spectroscopy at the Canadian Synchrotron Radiation Facility, SRC-Madison, WI, to address questions regarding the chemical environment, oxidation state and physical distribution (surficial versus intercrystalline) of the sulphur within the hematite minerals. XANES S K-edge FY and TEY and L-edge TEY spectra indicate that the sulphur predominantly occurs as sulphate having a formal oxidation state of S 6+ and is largely distributed within the hematite matrix at concentrations between approximately 0.04 and 4.7 %. The XANES S K- and L-edge absorption spectra have also been used to assess the effectiveness of leach treatments employing HNO 3 and NH 4 OH solutions for the removal of sulphate from the hematite minerals. Here, the spectra indicate that a 0.05M HNO 3 solution was largely ineffective at removal of surficial and intercrystalline sulphate whereas 1 to 4M NH 4 OH leach solutions appear to have variably removed sulphate from the uppermost regions (5 to 30 nm depth) of the hematite minerals. Overall integration of the XANES S K-edge and L-edge TEY and FY spectra provides both unique information regarding the distribution of sulphate within the hematite matrix and a means to evaluate the effectiveness of leach processes used to remove sulphate from hematite minerals.
Exploratory Experiments: Photodetachment of Negative Ions by Energetic Photons Thomas Kvale 1 , Song Cheng 1 , David Seely 2 , and Jeffrey Thompson 3 1 The University of Toledo, Toledo, OH 43606 2 Albion College, Albion, MI 49224 3 The University of Nevada, Reno, NV 89557 Abstract One of the current investigations in Atomic Physics is the electron-electron interaction in atoms by placing atoms in "exotic" states. A unique opportunity exists to perform a series of experiments which will probe this interaction by examining continuum states in various atomic species by photodetaching negative ions. Synchrotron radiation is useful in providing a continuously tunable source of photons over the energy range of interest. Various theories [1, 2] predict the photodetachment cross sections are rich in features (both minima and resonances) in this photon energy range. This situation makes these studies ideally suited for providing stringent tests of our current understanding of atomic structure. The specific experiments listed in this abstract are representative of the types of experiments possible and are only the first in an extended series of experiments that are currently of great interest in atomic physics. The first series of experiments that are proposed will probe the photon energy region from 4eV to 20 eV in a variety of relatively light elements. Gribakin, et al. [1] predicted the photodetachment cross sections for the outer np and nearby ns subshells of C - 2p 34 S, Si - 3p 34 S, and Ge - 4p 34 S. The np photodetachment cross sections have minima around 5eV above the negative ion ground states and then rise to maxima at around 8 eV before gradually falling again. The minima have widths of order of 0.5 eV, whereas the maxima have widths of several eV. By contrast, most of the predicted [2] resonances in Be - ( 4 P o , 4 D o , and 4 S o ) have widths of order of 10-50 meV. These proposed experiments complement previous photodetachment experiments of the authors at lower photon energies. With an estimated photon flux of 10 12 photon/s, an ion current of 100 nA, and the predicted photodetachment cross sections, we expect a photoelectron current of approximately 10-1000 e - /s. An apparatus (PHOTO-2) has been constructed for conducting this series of photodetachment experiments (see Figure). Briefly, it consists of: a 0 - 50kV negative ion accelerator; a dodecapole chamber for merging the ion and photon beams; an interaction chamber of approximately 30 cm long; and data acquisition chamber. Photodetached electrons are energy analyzed by a hemispherical energy analyzer located
Page 2 and 3:
Welcome to the 36 th SRC Users’ M
Page 4 and 5: 12:20 - 1:10 Lunch 1:10 -1:45 Poste
Page 6 and 7: Administration Executive Director D
Page 8 and 9: STATUS OF THE SRC BEAMLINES AND INS
Page 10 and 11: ACCELERATOR DEVELOPMENTS Ken Jacobs
Page 12 and 13: HIGH ENERGY RESEARCH POSSIBILITIES
Page 14 and 15: ATOMICALLY UNIFORM THIN FILMS ON SI
Page 16 and 17: calculated binding energies of the
Page 18 and 19: MANY-ELECTRON EFFECTS ON THE XE 5S
Page 20 and 21: PHOTOELECTRON SPECTROMETRY OF ATOMI
Page 22 and 23: PHOTOEMISSION STUDY OF USb AND UTe
Page 24 and 25: CANADIAN SYNCHROTRON RADIATION FACI
Page 26 and 27: SELF-ASSEMBLY OF BLOCK COPOLYMERS O
Page 28 and 29: A B S T R A C T S
Page 30 and 31: Photoemission spectra, a.u. -0.3 -0
Page 32 and 33: THE INITIAL AND FINAL STATE BANDS I
Page 34 and 35: TRANSITION LAYERS AT BURIED FERROMA
Page 36 and 37: LOW-DIMENSIONAL ELECTRONS AT SILICO
Page 38 and 39: SUBCELLULAR DISTRIBUTION OF MOTEXAF
Page 40 and 41: LINEAR POLARIZATION MEASUREMENTS OF
Page 42 and 43: Fig.1: Photoemission spectra of opt
Page 44 and 45: The sample manipulator has a cool d
Page 46 and 47: Cr and Fe but for these U systems t
Page 48 and 49: [4] G. -H. Gweon, J. W. Allen, and
Page 50 and 51: References [1] S. Cho, Y. Kim, A. D
Page 52 and 53: [3] D. L. Mills, Physical Review B
Page 56 and 57: in the data acquisition chamber. Th
Page 58 and 59: spatially resolved chemistry of the
Page 60 and 61: THE RELATIONSHIP BETWEEN PHOSPHATE
Page 62 and 63: PHOTOEMISSION STUDIES OF QUANTUM WE
Page 64 and 65: Ag surface state such that it moves
Page 66 and 67: HIGH-RESOLUTION STUDY OF THE LITHIU
Page 68 and 69: RELATIVE PARTIAL CROSS SECTIONS AND
Page 70 and 71: Christian Ast Max-Planck Institute
Page 72 and 73: David L. Huber Physical Sciences La
Page 74 and 75: Tom Miller University of Illinois a
Page 76 and 77: Eric Wiedemann University of Wiscon
Page 78 and 79: Pete Hagen Phone: (608) 877-2154 Em
Page 80: NOTES
show all

SRC Users' Meeting - Synchrotron Radiation Center - University of ...

Create successful ePaper yourself

Delete template?

Save as template?