A combined He-atom scattering and theoretical study of the low energy vibrations of physisorbed monolayers of Xe on Cu(111) and Cu(001) Abstract The surface phonon dispersion curves of commensurate Xe monolayers on Cu(111) and incommensurate Xe monolayers on Cu(001) surfaces have been measured using He atom scattering (HAS) time of flight (TOF) spectroscopy. The TOF spectra are interpreted by c...

The intrinsic non-radiative decay (internal conversion) from the triplet excited state in phosphorescent dyes can be described by a multi-phonon emission process. Since non-radiative decay of triplet excitons can be a significant process in organic light-emitting diodes, a detailed understanding of this decay mechanism is important if the overall device efficiency is to be controlled. We compar...

It has been recently shown, using ab-initio methods, that bulk diamond is characterized by a giant band–gap renormalization (∼ 0.6 eV) induced by the electron–phonon interaction. This result casts doubt on the accuracy of purely electronic calculations. In this work we show that in polymers, compared to bulk materials, due to the larger amplitude of the atomic vibrations the real excitations of...

Neutron powder diffraction and inelastic neutron scattering measurements were performed on crystalline tetracene, a molecular semiconductor of triclinic crystal structure that adopts a herringbone layered motif, as a function of pressure up to 358 MPa. In combination with theoretical and simulated computations, these measurements permit detailed characterization of the structural and vibrationa...

O ptical lattices are key elements in the effort to use ultracold atoms for quantum simulation, quantum computing, and atomic clocks. These lattices rely on light forces to precisely hold atoms in space and to individually control their internal states [1]. Researchers strive for nearly perfect periodic lattice structures using state-of-the-art laser systems, but the atoms can interfere with th...

Abstract The covariant particle-vibration coupling model within the time blocking approximation is employed to supplement the Relativistic Random Phase Approximation (RRPA) with coupling to collective vibrations. The Bethe-Salpeter equation in the particle-hole channel with an energy dependent residual particle-hole (p-h) interaction is formulated and solved in the shell-model Dirac basis as we...

Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature T(el) while leaving the lattice temperature T(l) low; subsequently the hot ...

Confocal Raman spectroscopy is applied to identify ferroelectric domain structure sensitive phonon modes in potassium titanyl phosphate. Therefore, polarization-dependent measurements in various scattering configurations have been performed to characterize the fundamental Raman spectra of the material. The obtained spectra are discussed qualitatively based on an internal mode assignment. In the...

Inelastic X-ray scattering with meV energy resolution (IXS) is an ideal tool to measure collective excitations in solids and liquids. In non-resonant scattering condition, the cross-section is strongly dominated by lattice vibrations (phonons). However, it is possible to probe additional degrees of freedom such as magnetic fluctuations that are strongly coupled to the phonons. The IXS spectrum ...

Making use of the classical second-moment sum rule, it is possible to convert a series of constant-Q x-ray Brillouin scattering scans (Q momentum transfer) into a series of constant frequency scans over the measured Q range. The method is applied to literature results for the longitudinal phonon dispersion in several glass formers. The constant frequency scans are well fitted in terms of a Q-in...