The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
D Sokolovski - One of the best experts on this subject based on the ideXlab platform.
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statistics of resonance and Nonresonance tunneling of fermionized cold atoms
Physical Review A, 2014Co-Authors: D Sokolovski, L M BaskinAbstract:We show that a short-range strong repulsive (contact) interaction between the particles in the barrier may change the statistics of two-particle tunnelling. In the case of a resonance of a width $\Gamma$, the effect would be observed if the time between the two impacts is of order of $\hbar/\Gamma$. The statistics of non-resonance tunnelling across a broad potential barrier remain unaffected, which suggests that there is no appreciable delay in the classically forbidden region.
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traversal time wave function analysis of resonance and Nonresonance tunneling
Physical Review A, 1994Co-Authors: D Sokolovski, S Brouard, J N L ConnorAbstract:A generalized wave function is defined for an arbitrary real functional. Properties of the traversal-time wave function are investigated for one-dimensional scattering at a fixed energy. A Heisenberg-type uncertainty relation is derived from the traversal-time wave function. Traversal-time probability distributions for a Larmor clock measurement are studied in detail. The high-resolution limit of a traversal-time measurement is examined. The use of ``fast'' and ``slow'' arguments in a traversal-time analysis is discussed. The systems studied include free motion, resonance, and Nonresonance tunneling through a double-\ensuremath{\delta}-function potential, rectangular barrier, absorbing optical potential, and interaction with a slow oscillator.
Richard P Van Duyne - One of the best experts on this subject based on the ideXlab platform.
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plasmon sampled surface enhanced raman excitation spectroscopy
Journal of Physical Chemistry B, 2003Co-Authors: Christy L Haynes, Richard P Van DuyneAbstract:This work presents the first systematic study of the surface-enhanced Raman-scattering (SERS) properties of nanosphere lithography (NSL) derived Ag nanoparticles. Furthermore, it demonstrates the necessity of correlating nanoparticle structure and localized surface plasmon resonance (LSPR) spectroscopic data in order to effectively implement SERS on nanofabricated surfaces that have narrow (∼100 nm) LSPR line widths. Using nanoparticle substrates that are structurally well characterized by atomic force microscopy, the relationship between the LSPR extinction maximum (λmax) and the SERS enhancement factor (EF) is explored in detail using the innovative approach of plasmon-sampled surface-enhanced Raman excitation spectroscopy (PS-SERES). PS-SERES studies were performed as a function of excitation wavelength, molecular adsorbate, vibrational band, and molecule-localized resonance or Nonresonance excitation. In each case, high S/N ratio spectra are achieved for samples with an LSPR λmax within a ∼120-nm wind...
A M Shalagin - One of the best experts on this subject based on the ideXlab platform.
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anomalous absorption of light under Nonresonance conditions
Quantum Electronics, 2007Co-Authors: A I Parkhomenko, A M ShalaginAbstract:The absorption spectrum of a weak probe field in atomic vapours of rubidium, cesium and samarium in the presence of a strong field is studied theoretically. It is shown that away from resonance with an atomic transition, the probe radiation may have an anomalously high absorption coefficient (several times higher than the resonance value) in an anomalously narrow spectral range. The ultranarrow resonance in the probe-field absorption line wing is not related to any real transitions in the atom. Its position is determined by detuning from resonance frequency and by the strong-field intensity. It is shown that for identical frequencies of the strong and probe waves, the resonance can be recorded by using weak magnetic fields. The effect can be applied in the ultrahigh resolution spectroscopy and for precision measurements of the magnetic field strength.
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population inversion induced by collisions in a two level system under Nonresonance optical excitation
Physical Review Letters, 2002Co-Authors: R V Markov, A I Plekhanov, A M ShalaginAbstract:When the gas particles, which can be considered as a two level quantum system, are affected by frequent collisions with buffer gas particles (thermal reservoir), the spectral densities of the Einstein coefficients for absorption and induced emission are unequal to each other far from the absorption (emission) line. The relationship between the spectral densities at the specified condition reveals new physical phenomena. The mostly convincing example is the fact that population inversion is established in a two level system under Nonresonance optical excitation. This effect is experimentally observed as a lasing on sodium resonance transitions.
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population inversion on transitions to the ground state of atoms upon Nonresonance absorption of laser radiation
Journal of Experimental and Theoretical Physics, 2001Co-Authors: Roman V Markov, A I Plekhanov, A M ShalaginAbstract:Lasing at the resonance transitions (D1− and D2−lines) of sodium was observed in the superradiance mode upon Nonresonance optical excitation in the presence of a buffer gas. The dependences of the lasing intensity on the exciting radiation intensity and on the detuning of its frequency from the frequencies of resonance transitions were studied. It is found that, under specific conditions of the experiment (high pressure of a buffer gas and a rather high radiation intensity), in the case of a large positive detuning of the exciting radiation frequency from the resonance (“working”) transition frequency, the population inversion is produced at the “ working” transition, which results in lasing.
J N L Connor - One of the best experts on this subject based on the ideXlab platform.
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traversal time wave function analysis of resonance and Nonresonance tunneling
Physical Review A, 1994Co-Authors: D Sokolovski, S Brouard, J N L ConnorAbstract:A generalized wave function is defined for an arbitrary real functional. Properties of the traversal-time wave function are investigated for one-dimensional scattering at a fixed energy. A Heisenberg-type uncertainty relation is derived from the traversal-time wave function. Traversal-time probability distributions for a Larmor clock measurement are studied in detail. The high-resolution limit of a traversal-time measurement is examined. The use of ``fast'' and ``slow'' arguments in a traversal-time analysis is discussed. The systems studied include free motion, resonance, and Nonresonance tunneling through a double-\ensuremath{\delta}-function potential, rectangular barrier, absorbing optical potential, and interaction with a slow oscillator.
Christy L Haynes - One of the best experts on this subject based on the ideXlab platform.
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plasmon sampled surface enhanced raman excitation spectroscopy
Journal of Physical Chemistry B, 2003Co-Authors: Christy L Haynes, Richard P Van DuyneAbstract:This work presents the first systematic study of the surface-enhanced Raman-scattering (SERS) properties of nanosphere lithography (NSL) derived Ag nanoparticles. Furthermore, it demonstrates the necessity of correlating nanoparticle structure and localized surface plasmon resonance (LSPR) spectroscopic data in order to effectively implement SERS on nanofabricated surfaces that have narrow (∼100 nm) LSPR line widths. Using nanoparticle substrates that are structurally well characterized by atomic force microscopy, the relationship between the LSPR extinction maximum (λmax) and the SERS enhancement factor (EF) is explored in detail using the innovative approach of plasmon-sampled surface-enhanced Raman excitation spectroscopy (PS-SERES). PS-SERES studies were performed as a function of excitation wavelength, molecular adsorbate, vibrational band, and molecule-localized resonance or Nonresonance excitation. In each case, high S/N ratio spectra are achieved for samples with an LSPR λmax within a ∼120-nm wind...
