Ultrafast fluorescence upconversion has been used to probe electronic excitation transfer within the B800B820 light-harvesting antenna of Rhodopseudomonas acidophila strain 7050. Emission from the carotenoid S2 band decays in 54 ( 8 fs, and the bacteriochlorophyll B820 Qy band rises in approximately 110 fs. The B820 Qy rise time is wavelength-dependent. Energy-transfer rates between the caroten...

The group theoretical analysis of the electronic structure of l,4-dihydro-l,4-bis (dicyanoinethylene)triptycene leads to an interesting but rarely documented notion, "charge transfer transition for symmetry forbidden charge transfer interaction" , which was supported by the substituent effects on the charge transfer band shifts. The substituent effects on the charge transfer band shifts were al...

We theoretically analyze the excitation energy transfer between two closely spaced linear molecular J-aggregates, whose excited states are Frenkel excitons. The aggregate with the higher (lower) exciton band edge energy is considered as the donor (acceptor). The celebrated theory of Förster resonance energy transfer (FRET), which relates the transfer rate to the overlap integral of optical spec...

Under 4.507 eV excitation, the SrS : Cu,Ag thin "lms exhibited a saturated blue emission at 2.876 eV at room temperature and two additional emission bands at 3.443 and 2.398 eV were also observed at 10 K. By comparing with singly doped SrS : Cu and SrS : Ag, the two bands at 3.443 and 2.876 eV were assigned to the Ag emission bands and the 2.398 eV band to Cu emission. The enhancement of the 2....

We study the dynamics of metallic vertical stripes in cuprates within the three-band Hubbard model based on a recently developed time-dependent Gutzwiller approximation. As doping increases, the optical conductivity shows transfer of spectral weight from the charge-transfer band towards (i) an incoherent band centered at 1.3 eV, (ii) a Drude peak, due mainly to motion along the stripe, and (iii...

Photo-excitation of chromophoric metal complexes electrostatically adsorbed to tin-oxide semiconductor nanoparticles is often accompanied by injection of electrons from the complexes into the semiconductor conduction band. The mechanism of back electron transfer (semiconductor particle to adsorbed molecule) for a family of tris-bipyridyl ruthenium and osmium complexes has been examined by evalu...

Traditional ab initio electronic structure calculations of periodic systems yield delocalized eigenstates that should be understood as adiabatic states. For example, excitons are bands of extended states which superimpose localized excitations on every lattice site. However, in general, in order to study the effects of nuclear motion on exciton transport, it is standard to work with a localized...

We show how to compute and to use the wavelength-dependent optical transfer function (OTF) to create color matches between spatially patterned images. We model the human OTF as a defocused optical system with a circular aperture. In our model, the defocus arises from axial chromatic aberration and wavelength-independent aberrations. From the computed OTF, it is apparent that high spatial-freque...

The spectral properties of LaVO(4), GdVO(4) and LuVO(4) crystals doped with Ce(3+), Pr(3+), Eu(3+) or Tb(3+) have been investigated in order to determine the position of the energy levels relative to the valence and conduction bands of the hosts along the trivalent and divalent lanthanide series. Pr(3+) and Tb(3+) ground state levels are positioned based on the electron transfer energy from tho...

Speech recognition in reverberant environments is still a challenge problem. In this paper, we first investigated the reverberation effect on subband temporal envelopes by using the modulation transfer function (MTF). Based on the investigation, we proposed an algorithm which normalizes the subband temporal modulation spectrum (TMS) to reduce the diffusion effect of the reverberation. During th...