Polarized, site-selected fluorescence was measured for light-harvesting complex II (LHCII), the major Chl a/b/xanthophyll binding light-harvesting complex of green plants. Upon selective excitation in the range of 679-682 nm at 4 K, separate zero-phonon lines and phonon wings could be observed, as well as sharp lines in the vibronic region of the emission: vibronic zero-phonon lines. The maximu...

Multiferroic (MF) materials exhibit a highly coupled, spontaneous ferroelectric polarization and magnetization. Coupling between electrical and magnetic properties in multiferroic materials makes them a promising material for the design of multifunctional device applications, but also because of the interesting physics found in this class of materials. The role or absence of phonon softening in...

The momentum conserving indirect excitonic transitions, from the ⌫ 15 valence band maximum to the conduction band minima close to the X 1 point in the Brillouin zone have been measured for GaP in piezo-modulated transmission. At 6 K, excitonic signatures due to phonon emission are observed at E gx ϩប␻ ph for TA͑X͒, LA͑X͒, and TO͑X͒ phonons ͑E gx ϭfree exciton band gap͒, whereas at 120 K signatures for ...

In the coherent anti-Stokes Raman scattering process, the spectrum of the generated optical phonon depends on the degree of temporal correlation between the pump laser field and the Stokes field. When the two fields are strongly correlated, such as when the Stokes field is generated with stimulated Raman scattering (SRS), the spectral shape of the optical phonon is found experimentally and theo...

The ab-plane reflectance of a Nd 1.85Ce 0.15CuO 4 single crystal (Tc523 K! has been measured from '35 to 9500 cm 21 at temperatures above and below Tc , and the optical properties calculated from a Kramers-Kronig analysis. A rich phonon spectrum is observed, and there are a number of c-axis infrared and Raman modes that are observed at low temperature which are believed to be activated by disor...

We report Raman studies of the Si–Si phonon band in Si12xGex alloys, where the excitation is by visible and ultraviolet ~351 nm! light. At a wavelength 351 nm, the optical penetration depth is extremely shallow ~'5 nm!. By varying the excitation from 351 to 514 nm, the optical penetration depth spans from 5 to 300 nm. Two sets of samples were examined. Thin layers grown using molecular beam epi...

We study the thermal properties of ultra-narrow silicon nanowires (NW) with diameters from 3 nm to 12 nm. We use the modified valence-force-field method for computation of phononic dispersion and the Boltzmann transport equation for calculation of phonon transport. Phonon dispersion in ultra-narrow 1D structures differs from dispersion in the bulk and dispersion in thicker NWs, which leads to d...

We investigate the effect of confinement and orientation on the phonon transport properties of ultrathin silicon layers of thicknesses between 1 nm and 16 nm. We employ the modified valence force field method to model the lattice dynamics and the ballistic Landauer transport formalism to calculate the thermal conductance. We consider the major thin layer surface orientations {100}, {110}, {111}...

Ti12xScxN alloys were used to investigate the effects of carrier density and the density of states ~DOS! at the Fermi level E f on vibrational modes, phonon anomalies, and superconducting transition temperatures Tc . Single-crystal Ti12xScxN layers, 2000 Å thick, with compositions spanning the entire alloy range (0<x <1), were grown on MgO~001! by ultrahigh vacuum reactive magnetron sputter dep...