8,038 research outputs found
Absorption and emission spectroscopies of homogeneous and inhomogeneously broadened multilevel systems in strong light fields
A method is introduced to calc., for a model set of mol. levels, the spectral line shapes expected for a variety of conventional laser expts. including absorption, hole burning, fluorescence line narrowing, and Raman scattering. The method allows the incident laser field to have arbitrary intensity. Furthermore, the effects of model gaussian or lorenzian inhomogeneous distributions are readily incorporated. Earlier results for a 2-level system are easily obtained and new results are presented for inhomogeneously broadened 2- and 3-level systems, and for the effects of pure dephasing on the strong field spectra. The differences between fluorescence and Raman in strong fields, and the effect of strong fields on the spontaneous emission of inhomogeneously broadened transitions were described. Some predictions are made regarding line narrowing expts. in the strong-field limit
Observation on the influence of non-acoustical factors on perceived noise annoyance in a field experiment (invited paper)
Comparison of a combined quantum mechanics/interatomic potential function approach with its periodic quantum-mechanical limit: Proton siting and ammonia adsorption in zeolite chabazite
Published versio
Silica-rich vein formation in an evolving stress field, Atlantis Bank Oceanic Core Complex
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Ma, Q., Dick, H. J. B., Urann, B., & Zhou, H. Silica-rich vein formation in an evolving stress field, Atlantis Bank Oceanic Core Complex. Geochemistry Geophysics Geosystems, 21(7), (2020): e2019GC008795, doi:10.1029/2019GC008795.Drilling 809âm Hole U1473A in the gabbro batholith at the Atlantis Bank Oceanic Core Complex (OCC) found two felsic vein generations: late magmatic fractionates, rich in deuteric water, hosted by oxide gabbros, and anatectic veins associated with dike intrusion and introduction of seawaterâderived volatiles. Microtextures show a change from compressional to tensional stress during vein formation. Temperatures and oxidation state were obtained from amphiboleâplagioclase and oxide pairs in the adjacent gabbros. Type I veins generally have reverse shearâsense, with restricted ÎFMQ, high Mt/Ilm ratios, and lowâamphibole Cl/F indicating deuteric fluids. They formed during percolation and fractionation of FeâTiârich melts into the primary olivine gabbro. Type II veins are usually hosted by olivine gabbro, occur at dike contacts and the margins of normalâsense shear zones. They are undeformed or weakly deformed, with highly variable ÎFMQ, low Mt/Ilm ratios, and highâamphibole Cl/F, indicating seawaterâderived fluids. The detachment fault on which the gabbro massif was emplaced rooted near the base of the dikeâgabbro transition beneath the rift valley. The ingress of seawater volatiles began at >800°C and penetrated at least ~590 m into the lower crust during extensional faulting in the rift valley and adjacent rift mountains. The sequence of the felsic vein formation likely reflects asymmetric diapiric flow, with a reversal of the stress regime, and a transition from juvenile to seawaterâderived volatiles. This, in turn, is consistent with fault capture leading to the large asymmetries in spreading rates during OCC formations and heat flow beneath the rift mountains.This study was supported by the Chinese National Key Basic Research Program (Grant 2012CB417300). H. Dick and B. Urann were supported by U.S. National Science Foundation (Grant OCEâMG&G 8371300). Emmanuel Codillo provided numerous useful comments and moral support. We thank N. Chatterjee for assistance in analyzing major element mineral composition in the MIT Electron Microprobe Laboratory. The great contributions of 360 Scientific Party for their initial shipboard description and interpretations of the Hole U1473A cores made this work possible. Special thanks go to C. J. MacLeod, Expedition cochief scientist, and Peter Blum, staff scientist, Stephen Midgley, IODP operations superintendent, and Siem Offshore James Samuel McLelland, offshore installation manager, ship's master Terry Skinner, and the crew and drillers on the JOIDES Resolution
Optical excitations in hexagonal nanonetwork materials
Optical excitations in hexagonal nanonetwork materials, for example,
Boron-Nitride (BN) sheets and nanotubes, are investigated theoretically. The
bonding of BN systems is positively polarized at the B site, and is negatively
polarized at the N site. There is a permanent electric dipole moment along the
BN bond, whose direction is from the B site to the N site. When the exciton
hopping integral is restricted to the nearest neighbors, the flat band of the
exciton appears at the lowest energy. The higher optical excitations have
excitation bands similar to the electronic bands of graphene planes and carbon
nanotubes. The symmetry of the flat exciton band is optically forbidden,
indicating that the excitons related to this band will show quite long lifetime
which will cause strong luminescence properties.Comment: 4 pages; 3 figures; proceedings of "XVIth International Winterschool
on Electronic Properties of Novel Materials (IWEPNM2002)
DGP Cosmology with a Non-Minimally Coupled Scalar Field on the Brane
We construct a DGP inspired braneworld scenario where a scalar field
non-minimally coupled to the induced Ricci curvature is present on the brane.
First we investigate the status of gravitational potential with non-minimal
coupling and observational constraints on this non-minimal model. Then we
further deepen the idea of embedding of FRW cosmology in this non-minimal
setup. Cosmological implications of this scenario are examined with details and
the quintessence and late-time expansion of the universe within this framework
are examined. Some observational constraints imposed on this non-minimal
scenario are studied and relation of this model with dark radiation formalism
is determined with details.Comment: 26 pages, 3 eps figure
Resonances in rotationally inelastic scattering of OH() with helium and neon
We present detailed calculations on resonances in rotationally and spin-orbit
inelastic scattering of OH (X\,^2\Pi, j=3/2, F_1, f) radicals with He and Ne
atoms. We calculate new \emph{ab initio} potential energy surfaces for OH-He,
and the cross sections derived from these surfaces compare favorably with the
recent crossed beam scattering experiment of Kirste \emph{et al.} [Phys. Rev. A
\textbf{82}, 042717 (2010)]. We identify both shape and Feshbach resonances in
the integral and differential state-to-state scattering cross sections, and we
discuss the prospects for experimentally observing scattering resonances using
Stark decelerated beams of OH radicals.Comment: 14 pages, 15 Figure
Testing whether muon neutrino flavor mixing is maximal
The small difference between the survival probabilities of muon neutrino and
antineutrino beams, traveling through earth matter in a long baseline
experiment such as MINOS, is shown to be an important measure of any possible
deviation from maximality in the flavor mixing of those states.Comment: Some revision has been made in the experimental discussions with two
new figures replacing the old ones and a clarification of the accuracy of the
perturbative result has been included. This version will be published in
Physical Review Letters. Title changed as asked by the editors of Physical
Review Letter
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