293 research outputs found

    Intrinsically biased electrocapacitive catalysis

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    We propose the application of the contact potential from metal-metal junctions or the built-in potential of semiconductor p-np-n junctions to induce or catalyze chemical reactions. Free of external sources, this intrinsic potential across microscale and nanoscale vacuum gaps establishes electric fields in excess of 10^7V/m. The electrostatic potential energy of these fields can be converted into useful chemical energy. As an example, we focus on the production of superthermal gas ions to drive reactions. Analysis indicates that this intrinsically biased electrocapacitive catalysis can achieve locally directed ion energies up to a few electron volts and local gas temperatureboosts in excess of 10^4K. Practical considerations for implementation and experimental tests are considered

    Perfect coupling of light to surface plasmons with ultra-narrow linewidths

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    We examine the coupling of electromagnetic waves incident normal to a thin silver film that forms an oscillatory grating embedded between two otherwise uniform, semi-infinite half spaces. Two grating structures are considered, in one of which the mid point of the Ag film remains fixed whereas the thickness varies sinusoidally, while in the other the mid point oscillates sinusoidally whereas the film thicknesses remains fixed. On reducing the light wavelength from the long wavelength limit, we encounter signatures in the transmission, T, and reflection, R, coefficients associated with: i) the short-range surface plasmon mode, ii) the long-range surface plasmon mode, and iii) electromagnetic diffraction tangent to the grating. The first two features can be regarded as generalized (plasmon) Wood's anomalies whereas the third is the first-order conventional (electromagnetic) Wood's anomaly. The energy density at the film surface is enhanced for wavelengths corresponding to these three anomalies, particularly for the long range plasmon mode in thin films. When exciting the silver film with a pair of waves incident from opposite directions, we find that by adjusting the grating oscillation amplitude and fixing the relative phase of the incoming waves to be even or odd, T+R can be made to vanish for one or the other of the plasmon modes; this corresponds to perfect coupling (impedance matching in the language of electrical engineering) between the incoming light and these modes.Comment: 13 pages, 5 figures. accepted J. Chem. Phy

    Coherently Controlled Nanoscale Molecular Deposition

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    Quantum interference effects are shown to provide a means of controlling and enhancing the focusing a collimated neutral molecular beam onto a surface. The nature of the aperiodic pattern formed can be altered by varying laser field characteristics and the system geometry.Comment: 13 pages (inculding 4 figures), LaTeX (Phys. Rev. Lett., 2000, in Press

    Utilization Of Spent Fowl In the Manufacture Of Chicken Restructured Steaks

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    Each year the poultry industry is faced with a large number of spent laying hens (spent fowl), which are often difficult to market at a reasonable price. If less desirable poultry carcasses such as spent hens could be utilized economically to create desirable new products, there would be considerable incentive to do so. Because of the maturity level of spent hens, their muscles are quite tough and, therefore, products made from them would have to be comminuted. A new method of comminution, called flaking, cleanly cuts frozen muscle into wafer—thin slices which aids in the binding properties upon further processing. The manufacture of restructured steaks involves, first, the flaking of meat and, secondly, the pressing of meat into a particular shape. The resulting product should be tender yet simulate the actual eating quality of a real steak. The objective of this study was to determine the optimum levels of white and dark meat required in the formulation of restructured steaks and to examine the feasibility of adding skin and fat to these products

    Utilization Of Goose Muscle In The Preparation Of Meat Rolls

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    South Dakota produces more domestic geese than any other state in the United States. Marketing of geese is decreasing due to importation of Canadian geese and a decreasing consumer demand. Research is needed to increase goose meat consumption. A large percentage of turkey meat is sold as retail convenience products such as rolls, yet there are virtually no comparable products on the market from goose meat. This study was undertaken to develop and evaluate an acceptable goose roll

    Squeezing of Atoms in a Pulsed Optical Lattice

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    We study the process of squeezing of an ensemble of cold atoms in a pulsed optical lattice. The problem is treated both classically and quantum-mechanically under various thermal conditions. We show that a dramatic compression of the atomic density near the minima of the optical potential can be achieved with a proper pulsing of the lattice. Several strategies leading to the enhanced atomic squeezing are suggested, compared and optimized.Comment: Latex, 9 pages, 10 figures, submitted to PR

    Fabrication Of Steaks From Spent Hens

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    Research at SDSU has demonstrated that meat from spent laying hens (spent fowl) can be utilized in the production of fabricated steaks and/or roasts. Previous studies utilized raw meat from carcasses that were manually deboned. Under commercial deboning, meat that has been precooked is more easily separated from the bone. Precooking reduces the ability for meat to hold together or bind in a processed product. Precooked and raw spent fowl muscles were compared as raw material for the production of fabricated steaks. The objective of this research was to produce from precooked spent fowl muscle a palatable restructured product that will withstand handling, cooking and serving

    Tunneling Ionization Rates from Arbitrary Potential Wells

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    We present a practical numerical technique for calculating tunneling ionization rates from arbitrary 1-D potential wells in the presence of a linear external potential by determining the widths of the resonances in the spectral density, rho(E), adiabatically connected to the field-free bound states. While this technique applies to more general external potentials, we focus on the ionization of electrons from atoms and molecules by DC electric fields, as this has an important and immediate impact on the understanding of the multiphoton ionization of molecules in strong laser fields.Comment: 13 pages, 7 figures, LaTe

    Analysis of surface waves generated on subwavelength-structured silver films

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    Using transmission electron microscopy (TEM) to analyse the physical-chemical surface properties of subwavlength structured silver films and finite-difference time-domain (FDTD) numerical simulations of the optical response of these structures to plane-wave excitation, we report on the origin and nature of the persistent surface waves generated by a single slit-groove motif and recently measured by far-field optical interferometry. The surface analysis shows that the silver films are free of detectable oxide or sulfide contaminants, and the numerical simulations show very good agreement with the results previously reported.Comment: 9 Figure

    Optical properties of metal nanoparticles with no center of inversion symmetry: observation of volume plasmons

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    We present theoretical and experimental studies of the optical response of L-shaped silver nanoparticles. The scattering spectrum exhibits several plasmon resonances that depend sensitively on the polarization of the incident electromagnetic field. The physical origin of the resonances is traced to different plasmon phenomena. In particular, a high energy band with unusual properties is interpreted in terms of volume plasmon oscillations arising from the asymmetry of a nanoparticle.Comment: 14 pages, 5 figures. Physical Review B, 2007, accepte
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