3,942 research outputs found
Franz Werfel\u27s Great Dilemma
Frederick C. Ellert investigates Franz Werfel\u27s crisis of faith based on Werfel\u27s Between Heaven and Earth, Paul Among Jews, Barbara, The Song of Bernadette and Star of the Unborn
Oscillatory Size-Dependence of the Surface Plasmon Linewidth in Metallic Nanoparticles
We study the linewidth of the surface plasmon resonance in the optical
absorption spectrum of metallic nanoparticles, when the decay into
electron-hole pairs is the dominant channel. Within a semiclassical approach,
we find that the electron-hole density-density correlation oscillates as a
function of the size of the particles, leading to oscillations of the
linewidth. This result is confirmed numerically for alkali and noble metal
particles. While the linewidth can increase strongly, the oscillations persist
when the particles are embedded in a matrix.Comment: RevTeX4, 5 pages, 2 figures, final versio
The propensity of molecules to spatially align in intense light fields
The propensity of molecules to spatially align along the polarization vector
of intense, pulsed light fields is related to readily-accessible parameters
(molecular polarizabilities, moment of inertia, peak intensity of the light and
its pulse duration). Predictions can now be made of which molecules can be
spatially aligned, and under what circumstances, upon irradiation by intense
light. Accounting for both enhanced ionization and hyperpolarizability, it is
shown that {\it all} molecules can be aligned, even those with the smallest
static polarizability, when subjected to the shortest available laser pulses
(of sufficient intensity).Comment: 8 pages, 4 figures, to be submitted to PR
Classification of phase transitions in small systems
We present a classification scheme for phase transitions in finite systems
like atomic and molecular clusters based on the Lee-Yang zeros in the complex
temperature plane. In the limit of infinite particle numbers the scheme reduces
to the Ehrenfest definition of phase transitions and gives the right critical
indices. We apply this classification scheme to Bose-Einstein condensates in a
harmonic trap as an example of a higher order phase transitions in a finite
system and to small Ar clusters.Comment: 12 pages, 4 figures, accepted for publication in Phys. Rev. Let
Thermal expansion in small metal clusters and its impact on the electric polarizability
The thermal expansion coefficients of clusters with and , and
are obtained from {\it ab initio} Born-Oppenheimer LDA molecular dynamics.
Thermal expansion of small metal clusters is considerably larger than that in
the bulk and size-dependent. We demonstrate that the average static electric
dipole polarizability of Na clusters depends linearly on the mean interatomic
distance and only to a minor extent on the detailed ionic configuration when
the overall shape of the electron density is enforced by electronic shell
effects. The polarizability is thus a sensitive indicator for thermal
expansion. We show that taking this effect into account brings theoretical and
experimental polarizabilities into quantitative agreement.Comment: 4 pages, 2 figures, one table. Accepted for publication in Physical
Review Letters. References 10 and 23 update
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