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Full-Text Articles in Physics
Wettability And “Petal Effect” Of Gaas Native Oxides, A. Gocalinska, Kamil Gradkowski, V. Dimastrodonato, L. O. Mereni, G. Juska, Guillaume Huyet, E. Pelucchi
Wettability And “Petal Effect” Of Gaas Native Oxides, A. Gocalinska, Kamil Gradkowski, V. Dimastrodonato, L. O. Mereni, G. Juska, Guillaume Huyet, E. Pelucchi
Cappa Publications
We discuss unreported transitions of oxidised GaAs surfaces between (super)hydrophilic and hydrophobic states when stored in ambient conditions. Contact angles higher than 90° and high adhesive force were observed for several air-aged epitaxial samples grown under different conditions, as well as on epi-ready wafers. Regardless of the morphologies of the surface, superhydrophilicity of oxygen-plasma treated samples was observed, an effect disappearing with storage time. Reproducible hydrophobicity was likewise observed, as expected, after standard HCl surface etching. The relation between surface oxides and hydrophobic/hydrophilic behaviour is discussed.
Causality And Relativistic Localization In One-Dimensional Hamiltonians, R E. Wagner, B T. Shields, M R. Ware, Qichang Su, Rainer Grobe
Causality And Relativistic Localization In One-Dimensional Hamiltonians, R E. Wagner, B T. Shields, M R. Ware, Qichang Su, Rainer Grobe
Faculty publications – Physics
We compare the relativistic time evolution of an initially localized quantum particle obtained from the relativistic Schrodinger, the Klein-Gordon and the Dirac equations. By computing the amount of the spatial probability density that evolves outside the light cone we quantify the amount of causality violation for the relativistic Schrodinger Hamiltonian. We comment on the relationship between quantum field theoretical transition amplitudes, commutators of the fields and their bilinear combinations outside the light cone as indicators of a possible causality violation. We point out the relevance of the relativistic localization problem to this discussion and comment on ideas about the supposed …
Electron-Positron Pair Creation Induced By Quantum-Mechanical Tunneling, M Jiang, W Su, X Lu, Z M. Sheng, Y T. Li, J Zhang, Rainer Grobe, Qichang Su
Electron-Positron Pair Creation Induced By Quantum-Mechanical Tunneling, M Jiang, W Su, X Lu, Z M. Sheng, Y T. Li, J Zhang, Rainer Grobe, Qichang Su
Faculty publications – Physics
We study the creation of electron-positron pairs from the vacuum induced by two spatially displaced static electric fields. The strength and spatial width of each localized field is less than required for pair creation. If, however, the separation between the fields is less than the quantum-mechanical tunneling length associated with the corresponding quantum scattering system, the system produces a steady flux of electron-positron pairs. We compute the time dependence of the pair-creation probability by solving the Dirac equation numerically for various external field sequences. For the special case of two very narrow fields we provide an analytical expression for the …
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Blackbody-Radiation Correction To The Polarizability Of Helium, Mariusz Puchalski, Ulrich D. Jentschura, Peter J. Mohr
Physics Faculty Research & Creative Works
The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric …
Excitability In Optically Injected Semiconductor Lasers: Contrasting Quantum- Well- And Quantum-Dot-Based Devices, Bryan Kelleher, C. Bonatto, Guillaume Huyet, Stephen P. Hegarty
Excitability In Optically Injected Semiconductor Lasers: Contrasting Quantum- Well- And Quantum-Dot-Based Devices, Bryan Kelleher, C. Bonatto, Guillaume Huyet, Stephen P. Hegarty
Cappa Publications
Excitability is a generic prediction for an optically injected semiconductor laser. However, the details of the phenomenon differ depending on the type of device in question. For quantum-well lasers very complicated multipulse trajectories can be found, while for quantum-dot lasers the situation is much simpler. Experimental observations show the marked differences in the pulse shapes while theoretical considerations reveal the underlying mechanism responsible for the contrast, identifying the increased stability of quantum-dot lasers to perturbations as the root.