Phonon-assisted exciton transitions in spherical GaAs nanocrystals embedded in SiO2 matrices have been studied by means of selective excitation spectroscopy. The optical and acoustic phononassisted optical transitions appear in the photoluminescence excitation, photoluminescence linenarrowing, and photoluminescence hole-burning spectra at low temperatures. Both direct (zerophonon) and phonon-as...

We present the first bioluminescence tomography algorithm that makes use of the PDEconstrained concept, which has shown to lead to significant savings in computation times in similar applications. Implementing a sequential quadratic programming (SQP) method, we solve the forward and inverse problems simultaneously. Using numerical results we show that the PDEconstrained SQP approach leads to ~1...

The effects of surface passivation on the photoluminescence (PL) properties of CdS nanoparticles oxidized by straightforward H2O2 injection were examined. Compared to pristine cadmium sulfide nanocrystals (quantum efficiency ≅ 0.1%), the surface-passivated CdS nanoparticles showed significantly enhanced luminescence properties (quantum efficiency ≅ 20%). The surface passivation by H2O2 injectio...

Several methods like biopsy, synchronous luminescence, HPGLC High precession gas liquid Chromatography, Raman spectroscopy; have been employed in the diagnosis of cancer. The laser induced fluorescence method is one of the useful and fast techniques of the cancer diagnosis. The intensity of the laser induced fluorescence increases as the malignancy increases. It may be used widely as it is port...

Using optical modulation spectroscopy, we report the direct observation of absorption lines from excitons localized in GaAs single quantum dot potentials. The data provide a measurement of the linewidth, resonance energy, and oscillator strength of the transitions, and show that states which decay primarily by nonradiative processes can be directly probed using this technique. The experiments e...

The synthesis of modified diketone ligands and the preparation of soluble Er3þ and Eu3þ tris-(b-diketone)phenantroline complexes are described. The complexes, embedded in thin films of different conjugated and non-conjugated polymeric host matrices were studied by luminescence spectroscopy and used as active layers in organic light emitting single layer diodes to observe their characteristic em...

We have been successful in adapting Fourier transform (FT) Raman accessories and spectrophotometers for sensitive measurements of the photoluminescence (PL) spectra of photovoltaic materials and devices. In many cases, the sensitivity of the FT technique allows rapid room-temperature measurements of weak luminescence spectra that cannot be observed using dispersive PL spectrophotometers. We pre...

The optical spectroscopy (absorption and luminescence) of a small concentration of lead (-10 ppm) incorporated into a NaC1:Sr crystal, containing a relatively higher concentration of Sr (-350 ppm), has been investigated. For samples annealed at room temperature after quenching, two overlapping absorption bands at 255 and 260 nm grow at the expenses of the A band typical of dissolved Pb +. For h...

Cleaved edge overgrowth and selective area epitaxy were combined for the synthesis of InAs quantum dot (QD) arrays with lateral sizes from 20 to 40 nm. The optical properties were locally assessed by confocal photoluminescence spectroscopy experiments at liquid helium temperature. The emission lines redshift as the lateral size of the QDs is increased. In agreement with a narrow size distributi...

We synthesized a thiosemicarbazone-functionalized flavin (Fl-(H)TSC: 2-[2-(3,4-dihydro-7,8-dimethyl-2,4-dioxobenzo[g]pteridin-10(2H)-yl)ethylidene]-hydrazinecarbothioamide) and its Pt(II) complex [Pt(Fl-TSC)(2)], and characterized it using X-ray diffraction, UV-visible absorption and luminescence spectroscopy. X-ray structural analysis for [Pt(Fl-TSC)(2)] revealed that the structure of the isoa...