Using enriched isotopes, we developed a method to elucidate the long-standing issue of Ge transport governing the strain-driven self-assembly. Here 76Ge was employed to form the 2D metastable layer on a Si(001) surface, while the 3D transition and growth were completed by additional evaporation of 70Ge. This isotope tracing combined with the analysis of the Ge-Ge LO phonon enables the tracking ...

The electron-phonon and Coulomb interactions inC60, and larger fullerene spheres are analyzed. The coupling between electrons and intramolecular vibrations give corrections ∼ 1 − 10 meV to the electronic energies for C60, and scales as R −4 in larger molecules. The energies associated with electrostatic interactions are of order ∼ 1 − 4 eV, in C60 and scale as R −1. Charged fullerenes show enha...

In this study, Bio-based carbon nanotubes (CNTs) have received considerable research attention due to their comparative advantages of high level stability, simplistic use, low toxicity and overall environmental friendliness. New potentials for improvement in heat transfer applications are presented due to their high aspect ratio, high thermal conductivity and special surface area. Phonons have ...

The interaction of electrons with anharmonic lattice vibrations is a long-standing problem that is not yet fully understood. What is surprising about this problem is that nearly all real materials are anharmonic ~as can be seen by the fact that they expand or contract upon heating!, but quasiharmonic models ~which replace the anharmonic phonons by harmonic phonons with temperature-dependent pho...

The skipping motion of Ne+ ions in grazing scattering from the LiF(001) surface is studied for velocity below 0.1 a.u. with a time-of-flight technique. It is demonstrated that suppression of electronic excitation and dominance of optical phonon excitation in the projectile stopping results in an odd 1,3,5,... progression of the energy loss peaks, a feature usually ascribed to subsurface channel...

Coherent phonons are excited in single-crystal tellurium by above-band-gap excitation with femtosecond laser pulses. Coherent infrared-active lattice vibrations give rise to the emission of electromagnetic waves at the phonon frequency. The excitation mechanism is based on the ultrafast buildup of a photo-Dember field and the coupling of a polar lattice mode to this field. The dynamics of the D...

Low-frequency Raman spectra of the porous structure formed on C-implanted silicon were examined using the 514.5 and 488 nm lines of Ar laser. The sharp low-frequency Raman peaks were observed with narrow linewidth and large intensity. According to usual vibration theory of the elastic body and related symmetry analysis, they are identified as the localized acoustic phonon torsional modes result...

The authors present here a simple analysis that explains the apparent strengthening of electron phonon interaction upon aggregation in conjugated polymer materials. The overall scheme is that of an intermolecular Herzberg-Teller effect whereby sidebands of a forbidden transition are activated by oppositely phased vibrations. The authors show that upon aggregation, the 0-0 emission becomes symme...

The application of terahertz pulsed spectroscopy to polymorphic, liquid crystalline and amorphous forms of pharmaceutical compounds has been investigated. The different polymorphic forms of carbamazepine and enalapril maleate exhibit distinct terahertz absorbance spectra. In contrast to crystalline indomethacin and fenoprofen calcium, amorphous indomethacin and liquid crystalline fenoprofen cal...

We have generated and detected coherent lattice vibrations in single-walled carbon nanotubes corresponding to the radial breathing mode (RBM) using ultrashort laser pulses. Because the band gap is a function of diameter, these RBM-induced diameter oscillations cause ultrafast band gap oscillations, thereby modulating the interband excitonic resonances at the phonon frequencies (3-9 THz). Excita...