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Full-Text Articles in Physics
Intra-Atomic Aspects Of Magnon-Plasmon Interactions, Ralph Skomski, Peter A. Dowben
Intra-Atomic Aspects Of Magnon-Plasmon Interactions, Ralph Skomski, Peter A. Dowben
Peter Dowben Publications
Magnon-plasmon interactions are modeled by considering the spin-dependent dielectric response of atoms placed in crystalline environment. Hund's exchange rules favor parallel spin alignment, but the strength of the exchange depends on the displacement of the centers of gravity of the atomic spin-up and spin-down electron charge clouds. The intra-atomic exchange is modeled by considering a Hubbard-type interaction, and interatomic interaction then yields a k-space dispersion. The eigenmodes of the plasma are a mixture of spin-up and spin-down degrees of freedom, described by a 2×2 interaction matrix. Minority and majority bands yield different plasmon frequencies. However, these modes are not orthogonal …
Metal Hybridization And Electronic Structure Of Tris(8-Hydroxyquinolato)Aluminum (Alq3), Anthony N. Caruso, D. L. Schulz, Peter A. Dowben
Metal Hybridization And Electronic Structure Of Tris(8-Hydroxyquinolato)Aluminum (Alq3), Anthony N. Caruso, D. L. Schulz, Peter A. Dowben
Peter Dowben Publications
The metal-organic complex Tris(8-hydroxyquinolato)aluminum (Alq3) has been studied by energy and light polarization dependent photoemission. Resonant photoemission was used to identify the molecular orbitals involved in metal chelation. When adsorbed on cobalt and gold surfaces, marked differences in the Alq3 metal-to-ligand bonds were observed. The results indicate intramolecular aluminum-to-ligand bonding through the oxygen heteroatom when Alq3 is adsorbed on gold, but through the nitrogen heteroatom when on cobalt. These results indicate that substrate interfacial complex formation plays an important role in the Alq3 molecular configuration and intramolecular bonding.
The Coadsorption And Interaction Of Molecular Icosahedra With Mercury, C.C. Ilie, Snjezana Balaz, Luis G. Rosa, Jun Zhang, P. Lunca-Popa, C. Bianchetti, R. Tittsworth, Jennifer I. Brand, B. Doudon, Peter A. Dowben
The Coadsorption And Interaction Of Molecular Icosahedra With Mercury, C.C. Ilie, Snjezana Balaz, Luis G. Rosa, Jun Zhang, P. Lunca-Popa, C. Bianchetti, R. Tittsworth, Jennifer I. Brand, B. Doudon, Peter A. Dowben
Peter Dowben Publications
We have investigated the changes in the electronic structure of molecularly adsorbed orthocarborane films, as a function of Hg co-adsorption, using photo emission. The interaction between Hg and molecular orthocarborane is weak and results in the formation of some small aggregates of Hg. This behavior is very different from alkali metals interaction with molecular carborane films and the interaction of Hg with semiconducting boron carbide films. Hg doping of semiconducting boron carbide may decrease the activation barrier for intrinsic carrier mobility, but does not significantly increase the number of carriers.
The Anomalous "Stiffness" Of Biphenydimethyldithiol, D.Q. Feng, Peter A. Dowben, R. Rajesh, Jody G. Redepenning
The Anomalous "Stiffness" Of Biphenydimethyldithiol, D.Q. Feng, Peter A. Dowben, R. Rajesh, Jody G. Redepenning
Peter Dowben Publications
Although organic adsorbates and thin films are generally regarded as "soft" materials, the effective Debye temperature, indicative of the dynamic motion of lattice normal to the surface, can be very high. For biphenyldimethyldithiol, the effective Debye temperature, determined from core level photoemission from the all carbon arene rings, is comparable to that of graphite. We associate this rigidity to the stiffness of the benzene rings, and the ordering in the molecular thin film. Measurements on the sulfur of poly(hexylthiophene) show that sulfur in an arene ring is less dominated by soft modes than the pendant sulfur of biphenyldimethyldithiol on the …
Mercury And C2B10 Icosahedra Interaction, Carolina C. Ilie, Petru Lunca-Popa, Jiandi Zhang, Bernard Doudin, Peter A. Dowben
Mercury And C2B10 Icosahedra Interaction, Carolina C. Ilie, Petru Lunca-Popa, Jiandi Zhang, Bernard Doudin, Peter A. Dowben
Peter Dowben Publications
We contrast the interaction of mercury with adsorbed orthocarborane films and semiconducting (dehydrogenated) boron carbide. Photoemission spectra reveal small shifts in orthocarborane (C2B10H12) molecular orbital binding energies as well as the shift in mercury 5d5/2 shallow core level binding energies, suggesting only small interaction between mercury and the molecular film. Mercury does, however, interact with decomposed orthocarboranes i.e. semiconducting boron carbide.
Evidence For Multiple Polytypes Of Semiconducting Boron Carbide (C2B10) From Electronic Structure, Petru Lunca-Popa, Jennifer I. Brand, Snjezana Balaz, Luis G. Rosa, Neil M. Boag, Mengjun Bai, Brian W. Robertson, Peter A. Dowben
Evidence For Multiple Polytypes Of Semiconducting Boron Carbide (C2B10) From Electronic Structure, Petru Lunca-Popa, Jennifer I. Brand, Snjezana Balaz, Luis G. Rosa, Neil M. Boag, Mengjun Bai, Brian W. Robertson, Peter A. Dowben
Peter Dowben Publications
Boron carbides fabricated via plasma enhanced chemical vapor deposition from different isomeric source compounds with the same C2B10H12 closo-icosa- hedral structure result in materials with very different direct (optical) band gaps. This provides compelling evidence for the existence of multiple polytypes of C2B10 boron carbide and is consistent with electron diffraction results.
Strain And Strain Relief In Gd[0001] Thin Films On Mo[112], T. Komesu, C. Waldfried, Peter A. Dowben
Strain And Strain Relief In Gd[0001] Thin Films On Mo[112], T. Komesu, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
Strain is known to affect magnetism, with possible dramatic effects as suggested by the theoretical calculations of Moruzzi and Marcus [1] and experimental results of Shinde and coworkers [2]. Barthotin and coworkers [3], and others. There is a general acceptance of the strong influence of magneto-elastic interactions on the Curie temperature and other magnetic properties. For the rare earth metals, the magnetic-elastic interactions are large [3-6]. For gadolinium compression is seen to lead to a suppression of T c [3,6] while expansion leads to an increase of T c[7,8]. Not only does strain affect the magnetic properties but it …
The Electronic Structure Of Oriented Poly [2-Methoxy-5-(2’-Ethyl-Hexyloxy)-1,4-Phenylene-Vinylene], D.K. Chambers, S. Karanam, D. Qi, Sandra Zivanovic Selmic, Yaroslav B. Losovyj, Luis G. Rosa, Peter A. Dowben
The Electronic Structure Of Oriented Poly [2-Methoxy-5-(2’-Ethyl-Hexyloxy)-1,4-Phenylene-Vinylene], D.K. Chambers, S. Karanam, D. Qi, Sandra Zivanovic Selmic, Yaroslav B. Losovyj, Luis G. Rosa, Peter A. Dowben
Peter Dowben Publications
Poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) adopts a preferential orientation on indium tin oxide. Although the basic building block of this polymer provides a negligible overall point-group symmetry, the polymer MEH-PPV packs with sufficient order to exhibit band structure. The polymer is fragile with bond cleavage evident following both argon-ion impact and ultraviolet radiation, but annealing leads to the restoration of much of the bond order.
Evidence For Multiple Polytypes Of Semiconducting Boron Carbide (C2B10) From Electronic Structure, Petru Lunca-Popa, Jennifer I. Brand, Snjezana Balaz, Luis G. Rosa, Neil M. Boag, Mengjun Bai, Brian W. Robertson, Peter A. Dowben
Evidence For Multiple Polytypes Of Semiconducting Boron Carbide (C2B10) From Electronic Structure, Petru Lunca-Popa, Jennifer I. Brand, Snjezana Balaz, Luis G. Rosa, Neil M. Boag, Mengjun Bai, Brian W. Robertson, Peter A. Dowben
Peter Dowben Publications
Boron carbides fabricated via plasma enhanced chemical vapor deposition from different isomeric source compounds with the same C2B10H12 closo-icosahedral structure result in materials with very different direct (optical) band gaps. This provides compelling evidence for the existence of multiple polytypes of C2B10 boron carbide and is consistent with electron diffraction results.