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Relaxation Time Of The Order Parameter In A High-Temperature Superconductor, G.L. Eesley, J. Heremans, M.S. Meyer, G.L. Doll, Sy_Hwang Liou
Relaxation Time Of The Order Parameter In A High-Temperature Superconductor, G.L. Eesley, J. Heremans, M.S. Meyer, G.L. Doll, Sy_Hwang Liou
Sy-Hwang Liou Publications
We present femtosecond time-resolved measurements on the high-Tc superconductor Tl2Ba2Ca2Cu3O10. At temperatures below Tc, we observe a relaxation process which is distinct from the equilibration of hot carriers in the normal state. Our results demonstrate an increasing relaxation rate as the superconducting gap opens. This is consistent with the behavior of conventional metallic superconductors.
Laser Cvd And Plasma Cvd Of Cro2 Films And Cobalt Doped Cro2 Films Using Organometallic Precursors, Peter A. Dowben, Marshall Onellion
Laser Cvd And Plasma Cvd Of Cro2 Films And Cobalt Doped Cro2 Films Using Organometallic Precursors, Peter A. Dowben, Marshall Onellion
Peter Dowben Publications
Chromium dioxide is deposited as a ferromagnetic layer onto selected portions of a substrate or over the entire substrate. Chromium hexacarbonyl vapor is introduced into a vacuum deposition chamber at e.g. 10 milliTorr and oxygen is introduced at e.g. 15 to 100 milliTorr. A UV laser beam is focused onto the substrate to form the CrO2 layer photolytically. The CrO2 layer can also be deposited by RF plasma deposition. This technique can also be employed for depositing MoC2, WC2, Mo2φ3, MoO2 or WO2. Magnetic recording or memory devices are …
The Relationship Of The Virtual Orbitals Of Self-Consistent-Field Theory To Temporary Negative Ions In Electron Scattering From Molecules, Donghai Chen, Gordon A. Gallup
The Relationship Of The Virtual Orbitals Of Self-Consistent-Field Theory To Temporary Negative Ions In Electron Scattering From Molecules, Donghai Chen, Gordon A. Gallup
Gordon Gallup Publications
The theory given here shows how certain of the virtual orbitals of self-consistent field (SCF) theory provide a natural ingredient for constructing basis functions to study the shape resonances associated with temporary molecular ions. We give specific calculations of resonant behavior in H2, N2, ethylene, cyclopropene, and cyclobutene. In addition, we show how the theory can rationalize the relationship between Koopmans' theorem values of the energy of a resonance and the experimental values. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.
Magnetism Of Rare-Earth–Transition-Metal Nanoscale Multilayers. Ii. Theoretical Analysis Of Magnetization And Perpendicular Magnetic Anisotropy, Z.S. Shan, David J. Sellmyer, Sitaram Jaswal, Y.J. Wang, J.X. Shen
Magnetism Of Rare-Earth–Transition-Metal Nanoscale Multilayers. Ii. Theoretical Analysis Of Magnetization And Perpendicular Magnetic Anisotropy, Z.S. Shan, David J. Sellmyer, Sitaram Jaswal, Y.J. Wang, J.X. Shen
David Sellmyer Publications
Systematic studies of rare-earth–transition-metal amorphous compositionally modulated films (CMF) permit the development of a detailed model for understanding the magnetization and perpendicular magnetic anisotropy and their distributions along the film normal. It is shown that the single-ion anisotropy of rare-earth ions with orbital angular momentum is the major contributor to the perpendicular anisotropy for this class of CMF. The calculated results agree well with the experimental data for Dy/Co and Tb/Fe CMF when the individual layer thicknesses are small enough (<10 Å); these films have structures which can be characterized as compositionally modulated amorphous alloys.
Magnetism Of Rare-Earth–Transition-Metal Nanoscale Multilayers. I. Experiments On Dy/Co, Dy/Fe, And Tb/Fe, Z.S. Shan, David J. Sellmyer
Magnetism Of Rare-Earth–Transition-Metal Nanoscale Multilayers. I. Experiments On Dy/Co, Dy/Fe, And Tb/Fe, Z.S. Shan, David J. Sellmyer
David Sellmyer Publications
Experimental investigations of magnetic and structural properties for rare-earth–transition-metal (RE-TM) compositionally modulated films (CMF) are presented in this paper. In particular, ARE/BTM including ARE=Dy and Tb and BTM=Fe, Co, and Ni, are studied. The layer thickness and temperature dependence of magnetic properties, which can be interpreted in terms of the antiferromagnetic coupling of RE and TM moments and their atomic distributions, are reported. These ARE/BTM CMF with nanoscale layer thicknesses exhibit perpendicular magnetic anisotropy (PMA) and the range of the layer thickness required for PMA is determined. The …
United States Patent: Metaginsulator Composites Having Improved Properties And Method For Their Preparation, Chia-Ling Chien, Gang Xiao, Sy-Hwang Liou
United States Patent: Metaginsulator Composites Having Improved Properties And Method For Their Preparation, Chia-Ling Chien, Gang Xiao, Sy-Hwang Liou
Sy-Hwang Liou Publications
Improved cermets having superior properties comprising a ferromagnetic metal and an insulator. By controlling process conditions, cermets having high magnetization and high coercivity as well as chemical stability, wear resistance and corrosion resistance are prepared. The cermets of this invention find particular utility as high density recording media.
Effects Of Magnetic Field And Temperature On The Critical Current Hysteresis In Tl-Ca-Ba-Cu-O Thin Films, Hung-Lun Chang, Jenh-Yih Juang, Sy_Hwang Liou, Tzeng-Ming Uen, Yih-Shun Gou
Effects Of Magnetic Field And Temperature On The Critical Current Hysteresis In Tl-Ca-Ba-Cu-O Thin Films, Hung-Lun Chang, Jenh-Yih Juang, Sy_Hwang Liou, Tzeng-Ming Uen, Yih-Shun Gou
Sy-Hwang Liou Publications
The behavior of the critical current density of Tl-Ca-Ba-Cu-O superconducting thin films in a cycling magnetic field was investigated. The hysteresis of the transport Jc manifested similar features to those found in polycrystalline Y-Ba-Cu-O and granular Nb, Al thin films in zero-field cooling. However, a novel result of the transport Jc in field-cooled samples has been observed. The results were attributed to the presence of a saturated trapped magnetic flux in the weaklink network. The effects of temperature on both the trapped flux and the transport Jc suggest the existence of various states of the trapped flux …
Predictions Of Cell Damage Rates For Lifesat Missions, Francis A. Cucinotta, William Atwell, Alva C. Hardy, Michael J. Golightly, John W. Wilson, Lawrence W. Townsend, Judy Shinn, John E. Nealy, Robert Katz
Predictions Of Cell Damage Rates For Lifesat Missions, Francis A. Cucinotta, William Atwell, Alva C. Hardy, Michael J. Golightly, John W. Wilson, Lawrence W. Townsend, Judy Shinn, John E. Nealy, Robert Katz
Robert Katz Publications
Radiological experiments with cell cultures are expected to be performed on Lifesat to study possible gravitational dependence on cellular response. Predictions of cell damage rates for well-studied systems are expected to help guide in the selection of orbits and the design of experiments. In this report we estimate the fractions of cell death and neoplastic transformation of C3H10T1/2 cells (cultured mouse cells) for the proposed Lifesat orbits. The parametric cellular track model of Katz et al. (refs. 1 and 2) is employed using cellular response parameters derived from the experiments of Yang et al. (refs. 3 and 4). The contributions …
Some "Do's" And "Don't'S" For Using Computers In Science Instruction, Glenn A. Sowell, Robert Fuller
Some "Do's" And "Don't'S" For Using Computers In Science Instruction, Glenn A. Sowell, Robert Fuller
Robert G. Fuller Publications
As science researchers and professors, we have had a fairly broad collection of experiences in using computers, from batch-processing and number crunching in large computer systems using FORTRAN and symbolic languages to teaching problem-solving courses for nonscience students using personal computers. While we claim no special computer expertise, we both own computers and are frequently called upon to offer advice to our colleagues who are greater novices than we are. Hence, on the basis of reflections on our experiences and observations of what we have seen other people and institutions do, we have compiled a list of “Do’s” and “Don’ts” …
Ab Initio Studies Of The Phase Transitions In K2Seo4, H. M. Lu, John R. Hardy
Ab Initio Studies Of The Phase Transitions In K2Seo4, H. M. Lu, John R. Hardy
John R. Hardy Papers
An ab initio model is developed for the potentials in ionic molecular solids in which the electron covalency within the molecular ions substantially affects the interionic interactions. By treating the intermolecular and intramolecular interactions on the basis of the true electron charge densities of the molecular ions, this new model leads to an accurate parameter-free description of the potentialenergy surfaces for such crystals. We performed first-principles static structural relaxation, supercell molecular-dynamics simulation, and lattice-dynamics studies for the room-temperature paraelectric phase and the lower-temperature ferroelectric superstructure of K2SeO4 and predicted with good accuracy the transition from the former …
Synchrotron Radiation Induced Chemical Vapor Deposition Of Thin Films From Metal Hexacarbonyls*, Derrick C. Mancini, Shikha Varma, John K. Simons, Richard A. Rosenberg, Peter A. Dowben
Synchrotron Radiation Induced Chemical Vapor Deposition Of Thin Films From Metal Hexacarbonyls*, Derrick C. Mancini, Shikha Varma, John K. Simons, Richard A. Rosenberg, Peter A. Dowben
Peter Dowben Publications
We have studied the initial stages of synchrotron radiation [SR] induced chemical vapor deposition [CVD] of metal-containing thin films from metal hexacarbonyl gases. We have measured the dependence of the initial deposition rate upon gas pressure at room temperature. Substrates were exposed to SR for single fills of the electron storage ring at constant pressure of Mo(CO)6, Cr(CO)6, or W(CO) 6 gas. Deposition was monitored in situ by Auger electron spectroscopy using the SW as the excitation source. The presence of metal, carbon, and oxygen in the deposited films was observed, and the results are consistent …
Laser-Induced Detachment Processes In An Electric Field, Bo Gao, Anthony F. Starace
Laser-Induced Detachment Processes In An Electric Field, Bo Gao, Anthony F. Starace
Anthony F. Starace Publications
An analytic momentum-space wave function for an electron in both laser and static uniform electric fields is presented. It is used to obtain analytic multiphoton detachment cross sections in a static, uniform electric field which include effects of static-field-induced electron-photon interactions. These general results are not restricted to weak laser intensities or to weak static-field strengths and depend only on (a) the electric dipole approximation and (b) the approximation that final-state electron-atom interactions are ignored. Four specific predictions of our general formulas for the most interesting case of linearly polarized light polarized along the static-field direction are presented for weakly …
Deposition Of Boron-Containing Films From Decaborane, James T. Spencer, Peter A. Dowben, Yoon G. Kim
Deposition Of Boron-Containing Films From Decaborane, James T. Spencer, Peter A. Dowben, Yoon G. Kim
Peter Dowben Publications
Depopsition of a boron nitride film is carried out by introducing decaborane and dry nitrogen or ammonia into a plasma-assisted chemical vapor deposition chamber. The nitrogen or ammonia partial pressure should provide an excess over the decarborane pressures for example 200 milliTorr of N2 or NH3 and 50 MilliTorr of B10H14. Other film layers can also be produced starting from decaborane.
The Long-Period Field Rr Lyrae Stars, Edward G. Schmidt, Charles G. Loomis, Andrew T. Groebner, Chris T. Potter
The Long-Period Field Rr Lyrae Stars, Edward G. Schmidt, Charles G. Loomis, Andrew T. Groebner, Chris T. Potter
Edward Schmidt Publications
VR light curve3 have been obtained for 16 faint variable stars with periods shorter than 1 day. Although, as expected, most of the light curves are typical of Bailey-type ab RR Lyrae stars, some have slower rises to maximum and flatter tops. Fourier decomposition was performed to further explore these trends. Combining these data with previously published Fourier decompositions of RR Lyrae light curves, we find that the Fourier coefficients are essentially constant for periods shorter than three-quarters of a day for Bailey-type ab RR Lyrae stars but that the amplitude ratios, R (12), R (13), and R (14), decrease …
Radiosensitivity Parameters For Cell Survival In Tradescantia And For Chromosome Aberrations In Chinese Hamster Cells, Robert Katz, G. Huang
Radiosensitivity Parameters For Cell Survival In Tradescantia And For Chromosome Aberrations In Chinese Hamster Cells, Robert Katz, G. Huang
Robert Katz Publications
Data for the loss of reproductive integrity of Tradescantia stamen hairs irradiated with 250 keV X rays and 0.43 and 5.6 MeV neutrons are fitted with radiosensitivity parameters from track theory, with E0 and m from X-ray data while σ0 and κ are then found from neutron irradiations. The X-ray data display a clear shoulder with 100% survival below 0.18 Gy and a “linear tail.” Data for abnormal metaphases and chromatid exchanges in Chinese Hamster cells have also been fitted with parameters. Parameters for abnormal metaphases are nearly identical with those obtained years ago for cell killing from …
Doubly Differential Detachment Cross Sections For Fast H-–Rare-Gas Collisions, Chih-Ray Liu, Anthony F. Starace
Doubly Differential Detachment Cross Sections For Fast H-–Rare-Gas Collisions, Chih-Ray Liu, Anthony F. Starace
Anthony F. Starace Publications
Detailed theoretical analyses are presented of the projectile-energy dependence as well as the target dependence of the electron-detachment collision processes, H-+T→H(n=2)+T*+e-. These analyses are illustrated by calculations of both projectile-frame and laboratory-frame doubly differential cross sections (DDCS’s) for 0.5-, 1.0-, and 1.5-MeV H- collisions with He targets and for 0.5-MeV H- collisions with Ne, Ar, Kr, and Xe targets; in addition, we present laboratory frame DDCS’s for 0.1-MeV H- collisions with Xe targets. Comparisons with available experimental data are given.
Two New Short-Period Cepheids, Edward G. Schmidt, Bradley A. Gross
Two New Short-Period Cepheids, Edward G. Schmidt, Bradley A. Gross
Edward Schmidt Publications
The General Catalogue of Variable Stars gives periods of slightly less than three-quarters of a day for the stars NO Cas and CN Tau. However, new photometry demonstrates that their periods are actually 2.6 and 1.8 days, respectively, and they are thus classical Cepheids. Fourier decompositions of their light curves are performed, and they are found to be members of a class of Cepheids with periods less than three days which may be related to the s-Cepheids. These two stars represent the shortest and longest known members of this class and thus are very useful in defining its properties in …
Possible Conserved Quantity For The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell
Possible Conserved Quantity For The Henon-Heiles Problem, Paul Finkler, C. Edward Jones, Glenn A. Sowell
Paul Finkler Papers
We study a power-series expansion for a conserved quantity K in the case of the two-dimensional Henon-Heiles potential. An alternative technique to that of Gustavson [Astron. J. 71, 670 (1966)] is applied to find the coefficients in the expansion for K. The technique is used to determine twelve orders for the conserved quantity K, more than twice as many as that calculated by Gustavson. We investigate the degree of constancy of our truncated K in regions where the motion is known to be chaotic and also where it is nonchaotic.
Intracavity Frequency Doubling Of A Nd:Yag Laser With An Organic Nonlinear Optical Crystal, Stephen Ducharme, W.P. Risk, W.E. Moerner, Victor Y. Lee, R.J. Twieg, G.C. Bjorklund
Intracavity Frequency Doubling Of A Nd:Yag Laser With An Organic Nonlinear Optical Crystal, Stephen Ducharme, W.P. Risk, W.E. Moerner, Victor Y. Lee, R.J. Twieg, G.C. Bjorklund
Stephen Ducharme Publications
Your access to Appl. Phys. Lett. is provided through the subscription of Univ Nebraska-Lincoln Lib. What is this? Scitation Citing Articles | CrossRef Citing Articles | All Citing Articles [ Previous / Next Abstract | Issue Table of Contents | Bottom of Page ] Applied Physics Letters -- August 6, 1990 -- Volume 57, Issue 6, pp. 537-539 Full Text: [ PDF (639 kB) ] Order Rightslink Permissions for Reuse About Rightslink view MyArticles What is this? Select up to 20 articles at a time. Intracavity frequency doubling of a Nd:YAG laser with an organic nonlinear optical crystal Stephen Ducharme, …
Measurement Of Parity Violation In The Elastic Scattering Of Polarized Electrons From 12C, P. A. Souder, R. Holmes, D. - H. Kim, K. S. Kumar, M. E. Schulze, K. Isakovich, G. W. Dodson, K. W. Dow, M. Farkhondeh, S. Kowalski, M. S. Lubell, J. Bellanca, M. Goodman, S. Patch, Richard Wilson, G. D. Cates, S. Dhawan, Timothy J. Gay, V. W. Hughes, A. Magnon, R. Michaels, H. R. Schaefer
Measurement Of Parity Violation In The Elastic Scattering Of Polarized Electrons From 12C, P. A. Souder, R. Holmes, D. - H. Kim, K. S. Kumar, M. E. Schulze, K. Isakovich, G. W. Dodson, K. W. Dow, M. Farkhondeh, S. Kowalski, M. S. Lubell, J. Bellanca, M. Goodman, S. Patch, Richard Wilson, G. D. Cates, S. Dhawan, Timothy J. Gay, V. W. Hughes, A. Magnon, R. Michaels, H. R. Schaefer
Timothy J. Gay Publications
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 12C nuclei. Our result is Aexpt=0.60±0.14±0.02 ppm, where the first error is statistical and the second is systematic. With a beam polarization of 0.37, we compute the isoscalar vector hadronic coupling constant γ̃ to be 0.136±0.032±0.009. The standard model predicts γ̃ =0.155 at the tree level, in agreement with our data.
Photodarkening Profiles And Kinetics In Chalcogenide Glasses, Stephen Ducharme, J. Hautala, P.C. Taylor
Photodarkening Profiles And Kinetics In Chalcogenide Glasses, Stephen Ducharme, J. Hautala, P.C. Taylor
Stephen Ducharme Publications
The spatial and temporal evolution of photodarkening in chalcogenide glasses is simulated by a simple kinetic model and tested against experiments. In the model, photodarkening, a gradual decrease of the energy of the absorption edge caused by above-band-gap illumination, is the additional absorption at defects created by the absorbed light. The defect-creation rate is proportional to the rate at which photons are absorbed either directly at the defect site or, alternatively, at a neighboring site. The depletion of the incident light within the sample is included and the resulting equations cast into a universal form that is applicable to realistic …
Kerr Effect Of Two-Medium Layered Systems, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam
Kerr Effect Of Two-Medium Layered Systems, Liang-Yao Chen, William A. Mcgahan, Z.S. Shan, David J. Sellmyer, John A. Woollam
David Sellmyer Publications
Detailed and practical expressions are given for the magneto-optical Kerr effect (MOKE) for various configurations of two media. One is a magneto-optic (MO) one, and the other is a nonmagnetic (NM) medium. For a system of two thick media with a single interface, with a first-order approximation in MOKE term Q, the Kerr function is determined by the product of a MOKE term Q and an optical term η. A second type of system includes a thin MO (or NM) layer deposited on a thick NM (or MO) substrate. For a MO/(NM-substrate) configuration, the Kerr function is related to …
Two-Photon Ionization Of The Ar Atom And Detachment Of The F- Ionv, Cheng Pan, Bo Gao, Anthony F. Starace
Two-Photon Ionization Of The Ar Atom And Detachment Of The F- Ionv, Cheng Pan, Bo Gao, Anthony F. Starace
Anthony F. Starace Publications
Theoretical calculations of the two-photon ionization cross section of argon and of the two-photon detachment cross section of the negative fluorine ion are presented for the energy region from threshold to the single-photon ionization or detachment threshold. Detailed analyses are presented of the effects of various kinds of electron correlations, whose contributions to the two-photon transition amplitudes are evaluated using variationally stable procedures to sum implicitly over intermediate states. These variationally stable procedures enable us to give much more reliable predictions in the region of the first few intermediate-state resonances in argon than were provided by previous calculations of one …
Magnetism And Anisotropy Of Tb/Fe Multilayers, Z.S. Shan, David J. Sellmyer
Magnetism And Anisotropy Of Tb/Fe Multilayers, Z.S. Shan, David J. Sellmyer
David Sellmyer Publications
Studies of the layer-thickness dependence of hysteresis loops for Tb/Fe compositionally modulated films (CMF) are reported. The characteristics of magnetic properties, such as magnetization and uniaxial anisotropy, which depend on the FE layer thickness, can be interpreted in terms of the compositional dependence of magnetic properties of the constituent subnetworks and the spatial distribution of the constituent atoms. The magnetic properties of Tb/Fe CMF are analyzed with a micromagnetic model, and the behavior of the anisotropy and constituent magnetization near the compensation point is discussed. Journal of Applied Physics is copyrighted by The American Institute of Physics.
Magnetic And Structural Properties Of Cocrta Films And Multilayers With Cr, David J. Sellmyer, D. Wang, J.A. Christner
Magnetic And Structural Properties Of Cocrta Films And Multilayers With Cr, David J. Sellmyer, D. Wang, J.A. Christner
David Sellmyer Publications
We report our studies of epitaxial growth of CoCrTa films on Cr underlayers and the properties of CoCrTa/Cr multilayers. The coercivity, Hc, strongly depends on Ta composition, sputtering conditions, and the thicknesses of the magnetic layer and Cr underlayer. An Hcvalue of 1300 Oe was obtained for a Ta composition of 2 at. %, a Cr underlayer thickness of 4000 Å, and a magnetic layer thickness of 400 Å. The x-ray data show that the high Hc occurs when crystallites of the Cr underlayer and CoCrTa layer are aligned with the Cr (200) and CoCrTa …
The Structure And Magneto-Optic Properties Of Mnal-Based Thin Films, J.X. Shen, Roger D. Kirby, David J. Sellmyer
The Structure And Magneto-Optic Properties Of Mnal-Based Thin Films, J.X. Shen, Roger D. Kirby, David J. Sellmyer
Roger Kirby Publications
We have measured the magnetization and magneto-optic Kerr rotation of sputtered thin films of Mn-Al-Cu ternary alloys over a wide composition range and for substrate temperatures between 25 and 450 °C. Magnetization and x-ray diffraction measurements suggest that our films are a mixture of the ferromagnetic kappa (κ) phase of MnAl and a highly paramagnetic amorphous phase. Room-temperature magneto-optic measurements on these films show a saturation polar Kerr rotation of up to 0.12° with little wavelength dependence.
Fabrication Of Ferromagnetic And Antiferromagnetic Chromium Oxides By Organometallic Chemical Vapor Deposition, Peter A. Dowben, Yoon Gi Kim, S. Baral-Tosh, G.O. Ramseyer, Chanyong Hwang, M. Onellion
Fabrication Of Ferromagnetic And Antiferromagnetic Chromium Oxides By Organometallic Chemical Vapor Deposition, Peter A. Dowben, Yoon Gi Kim, S. Baral-Tosh, G.O. Ramseyer, Chanyong Hwang, M. Onellion
Peter Dowben Publications
We have been able to fabricate CrO2 and Cr2O3 from ultraviolet photolytic and plasma-assisted decomposition of Cr(CO) 6 in an oxygen carrier gas. The composition of these films is uniform in composition and contains little contamination. Using magneto-optic Kerr effect measurements, we have been able to demonstrate that the CrO2 films are ferromagnetic.
The Chemistry Of The Gadolinium-Nickel Interface, D. Lagraffe, Peter A. Dowben, M. Onellion
The Chemistry Of The Gadolinium-Nickel Interface, D. Lagraffe, Peter A. Dowben, M. Onellion
Peter Dowben Publications
Gadolinium overlayers on Ni(111) have been studied by angle resolved photoemission, angle resolved AES, LEED, and RHEEB. We have observed pronounced interdiffusion of nickel with the gadolinium overlayer at temperatures as low as 150 K. This is in marked contrast with gadolinium overlayers on Cu(108) where substantial interdiffusion is not observed until 360 K, but is consistent with studies of ytterbium on nickel. [A. Nilsson, B Eriksson, N. Martenssom, J. N. Andersen, and J. Onsgaard, Phys. Rev. B 38,10357, ( 1988) and I. Chorkendorff, K. Onsgaard, J. Schmidt-May and R. Nyholm, Surf. Sci. 160, 587, (1985) .] There is a …
Ordering Of Metal Overlayers On Metal Substrates Studied Using Atom Beam Scattering, G. Vidali, C.W. Hutchings, Peter A. Dowben, M. Karimi, C. Moses, M. Foresti
Ordering Of Metal Overlayers On Metal Substrates Studied Using Atom Beam Scattering, G. Vidali, C.W. Hutchings, Peter A. Dowben, M. Karimi, C. Moses, M. Foresti
Peter Dowben Publications
We will illustrate how atom beam scattering (ABS) can be used to study the growth and ordering of adsorption of Hg on Cu(001). At low coverage (less than 2% of a monolayer), we obtain that the scattering cross section of He with (adsorbed) Hg is about 50 Å2. We find that mercury forms two stable phases on Cu(001) in the temperature range between 200 and 330 K, a c (2 x 2) and a high density c (4 x 4) phase. From ABS diffraction data, we can deduce the corrugation of the surface electron charge density of the …
The Effect Of Lateral Interactions On The Thermal Desorption Of N2 From Ni(100), Shikha Varma, Peter A. Dowben
The Effect Of Lateral Interactions On The Thermal Desorption Of N2 From Ni(100), Shikha Varma, Peter A. Dowben
Peter Dowben Publications
We have investigated the desorption of N2 from Ni(100) using thermal desorption spectroscopy (TDS). A modified Polanyi-Wigner equation has been used to obtain the desorption energy and the preexponential factor, both of which depend on the coverage of the adsorbate. We show that there is a large lateral interaction among the adlayer molecules when N2 goes down as ordered c (2 X 2) on Ni. In addition, the overlayer ordering, in the thermal desorption process, is observed to affect the thermal desorption spectra.