نتایج جستجو برای: phonon vibrations

تعداد نتایج: 30225  

2013
Woochul Kim Robert Wang Arun Majumdar

Scientists and engineers can exploit nanostructures to manipulate thermal transport in solids. This is possible because the dominant heat carriers in nonmetals – crystal vibrations (or phonons) – have characteristic lengths in the nanometer range. We review research where this approach is used and propose future research directions. For instance, concepts such as phonon filtering, correlated sc...

Journal: :Physical review letters 2007
T Slezak J Łazewski S Stankov K Parlinski R Reitinger M Rennhofer R Rüffer B Sepiol M Slezak N Spiridis M Zajac A I Chumakov J Korecki

The in-plane density of phonon states of clean Fe(110) surface was measured separately for the first, second, and further atomic monolayers using nuclear inelastic scattering of synchrotron radiation. The results show that atoms of the first layer vibrate with frequencies significantly lower and amplitudes much larger than those in the bulk, and that vibrational spectra along two perpendicular ...

2000
M. C. Cross Ron Lifshitz

The transmission coefficient for vibrational waves crossing an abrupt junction between two thin elastic plates of different widths is calculated. These calculations are relevant to ballistic phonon thermal transport at low temperatures in mesoscopic systems and the Q for vibrations in mesoscopic oscillators. Complete results are derived in a simple scalar model of the elastic waves, and results...

2008
Jianjun Xie Matthias Scheffler

Lattice relaxations, surface phonon spectra, surface energies, and work functions are calculated for Rh(100) and Rh(110) surfaces using density-functional theory and the fullpotential linearized augmented plane wave method. Both, the local-density approximation and the generalized gradient approximation to the exchange-correlation functional are considered. The force constants are obtained from...

Journal: :Physical review letters 2001
J Sinova J Schliemann A S Núñez A H MacDonald

We present a simple tight-binding model for the two-dimensional energy bands of polyacene field-effect transistors and for the coupling of these bands to lattice vibrations of their host molecular crystal. We argue that the strongest electron-phonon interactions in these systems originate from the dependence of intermolecule hopping amplitudes on collective molecular motion, and introduce a gen...

Journal: :Nano letters 2009
Takashi Kodama Ankur Jain Kenneth E Goodson

This paper reports results from electrical and thermal conduction measurements carried out on the DNA-gold composite for which the overall conduction is shown to be dominated by the DNA rather than the discontinuous gold coatings. The electrical and thermal conductivities of the composite were about 14 S/cm and 150 W/(m K) at room temperature, respectively. The resulting value of 3.6 x 10(-4) W...

Journal: :Physical review letters 2010
Richard C Hatch David L Huber Hartmut Höchst

The electron-phonon (e-p) interaction in pentacene (Pn) films grown on Bi(001) was investigated using photoemission spectroscopy. The spectra reveal thermal broadening from which we determine an e-p mass enhancement factor of lambda=0.36+/-0.05 and an effective Einstein energy of omega{E}=11+/-4 meV. From omega{E} it is inferred that dominant contributions to the e-p effects observed in angle-r...

Journal: :Journal of physics. Condensed matter : an Institute of Physics journal 2010
H Yavaş M van Veenendaal J van den Brink L J P Ament A Alatas B M Leu M-O Apostu N Wizent G Behr W Sturhahn H Sinn E E Alp

Phonons, the quantum mechanical representation of lattice vibrations, and their coupling to the electronic degrees of freedom are important for understanding thermal and electric properties of materials. For the first time, phonons have been measured using resonant inelastic x-ray scattering (RIXS) across the Cu K-edge in cupric oxide (CuO). Analyzing these spectra using an ultra-short core-hol...

2009
G. Benedek

An analytical theory of the optical transitions of a molecule bound at the surface of a He droplet is developed for the case of a strong softening of the excited-state nearest neighbor dynamics. The optical bandwidth is found to be determined by the zero-point kinetic energy released at the transition. The theory is applied to the triplet-triplet optical transition in Na2 molecule, for which an...

2004
H. W. Leite Alves J. L. A. Alves A. M. Santos L. M. R. Scolfaro J. R. Leite

In this work, we have calculated ab initio the phonon dynamics of the Ga-rich GaAs (100) (1 × 1), GaAs (100) (2 × 1), GaN (100) (1 × 1), GaAs (110) and GaN (110) surfaces. Our results for the (100) surfaces show that, while the (2 × 1) reconstruction is characterized by dimer vibrations, the (1 × 1) reconstruction presents interesting features which is closely related to the reduced mass of the...

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