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Title: Changes in photoemission spectra across the order/disorder transition in copper-gold alloys.
Creator: Liu, Wei, Florida Atlantic University, Jordan, Robin G.
Abstract/Description: Ultra-violet photoemission spectroscopy has been used in this project to investigate the changes in photoemission spectra across the order/disorder transition in Cu-Au alloys. Many obvious changes are observed in the valence band spectra of the different phases, particularly in the area of Au-related states. In Cu3Au, the binding energy of Au-4f core levels in the ordered phase are shifted from the pure metal value by an average of 0.46 +- 0.05eV to increased binding energy. In CuAu, the...
Show moreUltra-violet photoemission spectroscopy has been used in this project to investigate the changes in photoemission spectra across the order/disorder transition in Cu-Au alloys. Many obvious changes are observed in the valence band spectra of the different phases, particularly in the area of Au-related states. In Cu3Au, the binding energy of Au-4f core levels in the ordered phase are shifted from the pure metal value by an average of 0.46 +- 0.05eV to increased binding energy. In CuAu, the corresponding shift value in the ordered phase is 0.33 +- 0.05eV, also to increased binding energy. In both disordered Cu3Au and CuAu the value of the Au4f core level shift is reduced by 0.12eV from that of their ordered states. Some of the results are new, and others are in good agreement with previous studies.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15477
Subject Headings: Gold-copper alloys, Photoemission, Photoelectron spectroscopy, Order-disorder in alloys
Format: Document (PDF)

Title: Photoemission investigation of the electronic structure in iron rich iron-nickel alloys.
Creator: Cang, Song-Sheng., Florida Atlantic University, Jordan, Robin G.
Abstract/Description: The techniques of x-ray and ultra-violet photoemission spectroscopies have been used to investigate the electronic structures in Fe-30%Ni and Fe-27.5%Ni alloys in both the bcc and fcc phases. The similarities between the Fe 3s core level spectra, and between the XPS and UPS EDC's of the valence band, from the bcc and fcc phases of the Fe-Ni alloys, provide evidence that the Fe local magnetic moment persists in the fcc phase, and is about the same magnitude as in the bcc phase. The binding...
Show moreThe techniques of x-ray and ultra-violet photoemission spectroscopies have been used to investigate the electronic structures in Fe-30%Ni and Fe-27.5%Ni alloys in both the bcc and fcc phases. The similarities between the Fe 3s core level spectra, and between the XPS and UPS EDC's of the valence band, from the bcc and fcc phases of the Fe-Ni alloys, provide evidence that the Fe local magnetic moment persists in the fcc phase, and is about the same magnitude as in the bcc phase. The binding-energies of the Fe-2p1/2 and Fe-2p3/2 core levels of Fe-30%Ni and Fe-27.5%Ni are shifted from the values in pure Fe by + 0.40eV +- 0.05eV. The binding-energy of the Fe-3p core level of Fe-30%Ni is shifted from the value in pure Fe by + 0.40eV +- 0.05eV. The intensity of the Ni-3p core level in XPS spectra is considerably decreased when Fe-30%Ni has undergone the martensitic phase transition. The EDC's of the valence bands of Fe-30%Ni, Fe-27.5%Ni (in both the bcc and fcc phases) and pure Fe agree with published data.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15017
Subject Headings: Ferromagnetic materials, Alloys--Thermal properties, Photoelectron spectroscopy, Iron alloys
Format: Document (PDF)

Title: Photoemission study of Shockley-type surface states on the (111) surfaces of copper-gold alloys.
Creator: Masliah, Lilian Regina, Florida Atlantic University, Jordan, Robin G.
Abstract/Description: Angle-resolved UV photoelectron spectroscopy has been used to investigate some of the properties of the occupied Shockley-type surface states that exist on the (111) surfaces of Cu, Au, ordered Cu3Au and ordered CuAuI. These states appear in normal and off-normal spectra near the Fermi level and their binding energies are independent of photon energy; however, the intensity of their emission relative to that of the d-bands is photon energy dependent, decreasing monotonically from ArI to NeI...
Show moreAngle-resolved UV photoelectron spectroscopy has been used to investigate some of the properties of the occupied Shockley-type surface states that exist on the (111) surfaces of Cu, Au, ordered Cu3Au and ordered CuAuI. These states appear in normal and off-normal spectra near the Fermi level and their binding energies are independent of photon energy; however, the intensity of their emission relative to that of the d-bands is photon energy dependent, decreasing monotonically from ArI to NeI to HeI. As the emission angle is increased from the normal, the states move towards and eventually cross the Fermi level, and we have measured this dispersion in k space. We show that the occupied extents of the dispersion relations, delta k, are related to features of the bulk band structures. For example, in Cu and Au the surface state follows the dispersion of the uppermost occupied band edge in the vicinity of the L-point and so the delta k extent is related to the (111) neck radius on the Fermi surface. Because the changes in the delta k extents are of the same order as the experimental uncertainty, we are unable to determine precisely how they vary with composition. We have fitted the dispersion data to 'free-electron' parabolas and calculated an effective electron mass in each case; we find that the effective masses in the alloys are somewhat larger than in the pure metals. The photoemission measurements described here on CuAuI(111) are the first ever to be taken on an alloy of that composition.
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Date Issued: 1995
PURL: http://purl.flvc.org/fcla/dt/15221
Subject Headings: Photoemission, Photoelectron spectroscopy, Alloys, Surfaces (Physics)
Format: Document (PDF)

Title: An experimental study of LEED and UPS on bombarded and vacuum cleaved zinc(0001) surfaces.
Creator: Liu, Yu, Florida Atlantic University, Jordan, Robin G., Qiu, Shen-Li
Abstract/Description: Several Zn single crystals were grown by the Bridgman method and their orientations were determined by the Laue X-ray back-reflection method. Zn(0001) surfaces were prepared by vacuum cleaving and by Ar+ bombardment with annealing. LEED patterns and UPS spectra were taken on both the cleaved and bombarded Zn(0001) surfaces. The LEED patterns from cleaved surfaces showed 6-fold symmetry whereas those from bombarded surfaces showed a hexagonal array but with some differences: the spots with the...
Show moreSeveral Zn single crystals were grown by the Bridgman method and their orientations were determined by the Laue X-ray back-reflection method. Zn(0001) surfaces were prepared by vacuum cleaving and by Ar+ bombardment with annealing. LEED patterns and UPS spectra were taken on both the cleaved and bombarded Zn(0001) surfaces. The LEED patterns from cleaved surfaces showed 6-fold symmetry whereas those from bombarded surfaces showed a hexagonal array but with some differences: the spots with the same distances from the center of LEED pattern had different intensities and they were dimmer and more blurry compared to those from the cleaved surface. A value of 2.64+-0.07 A for the nearest neighbor spacing was determined from the LEED patterns. The UPS spectra showed that for both types of surfaces the 3d peak is at 9.8 eV with a spin splitting of 0.7 eV, which are in agreement with previous experimental and theoretical results. Differences in spectra between the two types of surfaces were found in the ratios of signal/background and in the ratios of the 3d doublet.
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Date Issued: 1996
PURL: http://purl.flvc.org/fcla/dt/15304
Subject Headings: Metal crystals, Engineering, Materials Science, Low energy electron diffraction, Photoelectron spectroscopy
Format: Document (PDF)

Title: Measurements of the core-level shifts and investigations of the Fe 3s lineshapes in Fe-V alloys using XPS.
Creator: Wang, Xiaotong, Florida Atlantic University, Jordan, Robin G.
Abstract/Description: A series of measurements of the various core level binding energies were carried out from pure Fe and V metals and three Fe-V alloys using x-ray photoemission spectroscopy. We observed a shift of the Fe and V core levels on alloying; we find that the binding energy shifts of the Fe core levels are small and those for V appear to increase with the number of Fe neighbors. We have also examined the relationship between the lineshape of the Fe 3s spectra and the Fe local moment in the Fe-V alloys...
Show moreA series of measurements of the various core level binding energies were carried out from pure Fe and V metals and three Fe-V alloys using x-ray photoemission spectroscopy. We observed a shift of the Fe and V core levels on alloying; we find that the binding energy shifts of the Fe core levels are small and those for V appear to increase with the number of Fe neighbors. We have also examined the relationship between the lineshape of the Fe 3s spectra and the Fe local moment in the Fe-V alloys. We find that a shoulder on the higher binding energy side of each spectrum becomes less apparent with increasing V concentration, i.e., as the local moment decreases. This implies that the spin-splitting of the Fe 3s core level may be used as a probe of the local moment in Fe-V alloys.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14782
Subject Headings: Photoemission, Photoelectron spectroscopy, Auger effect
Format: Document (PDF)

Title: Some calculated properties of beta prime-nickel aluminum.
Creator: Hines, Eric Lawrence, Florida Atlantic University, Jordan, Robin G.
Abstract/Description: The band structure, density of states, Fermi surface, bulk modulus and heat of formation were calculated for beta prime-NiAl using the SCF-LMTO-ASA method. The equilibrium lattice constant was also determined by minimizing the total energy. The angle-resolved and x-ray photocurrents from the valence bands were determined using the NEWPOOL and XPSI codes and the calculated spectra were compared with recent experimental measurements. In the former case, the calculations were carried out for the...
Show moreThe band structure, density of states, Fermi surface, bulk modulus and heat of formation were calculated for beta prime-NiAl using the SCF-LMTO-ASA method. The equilibrium lattice constant was also determined by minimizing the total energy. The angle-resolved and x-ray photocurrents from the valence bands were determined using the NEWPOOL and XPSI codes and the calculated spectra were compared with recent experimental measurements. In the former case, the calculations were carried out for the (001) surface using s-polarized light and included the experimentally observed relaxations of the top two layers with an Al termination. The overall agreement between the theoretical and experimental spectra is good, indicating that self-energy effects are not large.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14804
Subject Headings: Electronic structure, Solids--Data processing, Nickel-aluminum alloys
Format: Document (PDF)

Title: Photoemission investigation of the electronic structure in ordered and disordered copper gold.
Creator: Jiang, Yongjin, Florida Atlantic University, Jordan, Robin G., Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: The techniques of x-ray and ultra-violet photoelectron spectroscopies have been used to investigate the electronic structures in ordered (L10-structure) and disordered (fcc) CuAu. Large changes are observed in the valence band regions of the different phases, particularly in the vicinity of the Au-related states. The binding energies of the Cu-2p and Au-4f core levels in the ordered phase are shifted from the pure metal value by 0.27 +- 0.05 eV and 0.30 +- 0.05 eV, respectively. A small...
Show moreThe techniques of x-ray and ultra-violet photoelectron spectroscopies have been used to investigate the electronic structures in ordered (L10-structure) and disordered (fcc) CuAu. Large changes are observed in the valence band regions of the different phases, particularly in the vicinity of the Au-related states. The binding energies of the Cu-2p and Au-4f core levels in the ordered phase are shifted from the pure metal value by 0.27 +- 0.05 eV and 0.30 +- 0.05 eV, respectively. A small reduction of the Au-4f core level shift is found in the disordered phase. Details of the valence band structure and the shifts for the ordered phase are in accord with recently published calculations of the density of states. Investigations of the composition of the surface region using Auger electron spectroscopy indicate that there is excess Au in the surface region, in agreement with previous studies.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14702
Subject Headings: Photoemission, Order-disorder in alloys
Format: Document (PDF)

Title: The copper local density of states in equi-atomic copper-gold.
Creator: Dorsey, Anthony Travis., Florida Atlantic University, Jordan, Robin G., Qiu, Shen-Li
Abstract/Description: We attempted to isolate the individual Cu and Au contributions to the local density of states in equi-atomic CuAu using photoemission measurements with synchrotron radiation over the range 21 to 160eV. We compared our experimentally measured Au-5d/Cu-3d photoemission cross sections ratio with those of Yeh and Lindau (Atomic Data Nucl. Data Tables 32, 1, (1985)) and of Shirley et al (Physica Scripta 16, 398, (1977)) and found agreement with the former, suggesting difficulty in extracting the...
Show moreWe attempted to isolate the individual Cu and Au contributions to the local density of states in equi-atomic CuAu using photoemission measurements with synchrotron radiation over the range 21 to 160eV. We compared our experimentally measured Au-5d/Cu-3d photoemission cross sections ratio with those of Yeh and Lindau (Atomic Data Nucl. Data Tables 32, 1, (1985)) and of Shirley et al (Physica Scripta 16, 398, (1977)) and found agreement with the former, suggesting difficulty in extracting the Au local density of states. Hence, while others have suggested it is possible to isolate the Au local density of states at 50eV using similar methods, we found we could not. The density of states calculation and the photocurrent calculations at 50eV confirmed this by showing significant overlap of the Au and Cu states. Since the Au-5d states experience a Cooper minimum around 160eV, the experimental spectrum of CuAu at this photon energy contains very little Au contribution, thus allowing us to "experimentally determine" the Cu local density of states. The photocurrent calculations at 160eV confirmed the lack of Au contribution and comparison of experimental spectra with the photocurrent calculations at 160eV showed good agreement.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14960
Subject Headings: Photoemission, Order-disorder in alloys
Format: Document (PDF)

Title: The relationship between item difficulty and discrimination indices in multiple-choice tests in a physical science course.
Creator: Hotiu, Angelica, Jordan, Robin G., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description: We have developed a method of quantifying multiple-choice test items in an introductory physical science course in terms of the various tasks required to solve the problem. We assign a numerical level of difficulty to each task so that any question can be assigned a degree of difficulty, which is the sum of the individual levels of difficulty associated in each steps. Using the questions and results from the tests we have investigated the relationship between the degree of difficulty of each...
Show moreWe have developed a method of quantifying multiple-choice test items in an introductory physical science course in terms of the various tasks required to solve the problem. We assign a numerical level of difficulty to each task so that any question can be assigned a degree of difficulty, which is the sum of the individual levels of difficulty associated in each steps. Using the questions and results from the tests we have investigated the relationship between the degree of difficulty of each question and the corresponding discrimination index. Our results indicate that as the degree of difficulty increases so does the capability of the item to discriminate between students with different abilities. There is a maximum degree of difficulty beyond which the discrimination starts to decrease. At that point, test items become too difficult. Thus, it should be possible in future to design items that will provide optimum discrimination.
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Date Issued: 2006
PURL: http://purl.flvc.org/fau/fd/FA00000766
Subject Headings: Decision making, Curriculum planning, Examinations--Scoring, Educational tests and measurements, Universities and colleges--United States--Examinations--Design and construction
Format: Document (PDF)

Photoelectron spectroscopy (5)	+ -
Photoemission (5)	+ -
Order-disorder in alloys (3)	+ -
Alloys (1)	+ -
Alloys--Thermal properties (1)	+ -

Auger effect (1)	+ -
Curriculum planning (1)	+ -
Decision making (1)	+ -
Educational tests and measurements (1)	+ -
Electronic structure (1)	+ -
Engineering, Materials Science (1)	+ -
Examinations--Scoring (1)	+ -
Ferromagnetic materials (1)	+ -
Gold-copper alloys (1)	+ -
Iron alloys (1)	+ -
Low energy electron diffraction (1)	+ -
Metal crystals (1)	+ -
Nickel-aluminum alloys (1)	+ -
Solids--Data processing (1)	+ -
Surfaces (Physics) (1)	+ -
Universities and colleges--United States--Examinations--Design and construction (1)	+ -

Florida Atlantic University (9)	+ -
Jordan, Robin G. (9)	+ -
Charles E. Schmidt College of Science (2)	+ -
Department of Physics (2)	+ -
Qiu, Shen-Li (2)	+ -

Cang, Song-Sheng. (1)	+ -
Dorsey, Anthony Travis. (1)	+ -
Hines, Eric Lawrence (1)	+ -
Hotiu, Angelica (1)	+ -
Jiang, Yongjin (1)	+ -
Liu, Wei (1)	+ -
Liu, Yu (1)	+ -
Masliah, Lilian Regina (1)	+ -
Wang, Xiaotong (1)	+ -

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