Current Search: Photoemission (x)
View All Items
(1 - 6 of 6)
- Title
- Photoemission studies of FeRh.
- Creator
- Zhao, Biao, Florida Atlantic University, Qiu, Shen-Li
- Abstract/Description
-
Characterization and photoemission investigations were carried on an equiatomic FeRh alloy. The starting and ending temperatures of the phase transition were obtained by resistivity measurements; the results agree with previous work. We also measured the lattice constant of FeRh using a diffractometer and a Debye-Scherrer camera. The results of both methods are the same. Auger electron spectroscopy was carried out to study the surface of the sample and a composition analysis was conducted....
Show moreCharacterization and photoemission investigations were carried on an equiatomic FeRh alloy. The starting and ending temperatures of the phase transition were obtained by resistivity measurements; the results agree with previous work. We also measured the lattice constant of FeRh using a diffractometer and a Debye-Scherrer camera. The results of both methods are the same. Auger electron spectroscopy was carried out to study the surface of the sample and a composition analysis was conducted. Synchrotron-based photoemission and XPS have been used to investigate the electronic structure in FeRh. The Fe 3s and Rh 4s core level spectra show that the local moments on both Fe and Rh sites in FeRh alloy remain unchanged upon the phase transition from the antiferromagnetic (AF) to ferromagnetic (FM) states. The shifts of Fe 3s and Fe 3p core levels are large, while shifts of Rh 4s and Rh 4p core levels are very small. We discuss four possibilities why we do not observe the expected line-shape change of the Rh 4s core level.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/15428
- Subject Headings
- Iron-rhodium alloys, Photoemission
- 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.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14782
- Subject Headings
- Photoemission, Photoelectron spectroscopy, Auger effect
- 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.
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15221
- Subject Headings
- Photoemission, Photoelectron spectroscopy, Alloys, Surfaces (Physics)
- 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.
Show less - 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.
Show less - Date Issued
- 1993
- PURL
- http://purl.flvc.org/fcla/dt/14960
- Subject Headings
- Photoemission, Order-disorder in alloys
- Format
- Document (PDF)
- 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.
Show less - 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)
