Temperature dependence of the emission properties in a novel composite quantum-well-structure consisting of wide and narrow GaAs quantum wells (QWs) embedded in a GaAs/AlAs short-period superlattice (SPS) has been studied by steady-state and time-resolved photoluminescence (PL) measurements. At low temperature (~20 K), distinct PL peaks originating from the QWs and SPS are observed. When temper...

We have investigated the photoluminescence ~PL! from anodic alumina membranes with an ordered nanopore array formed on bulk Al foils. Most of the membranes fabricated by anodization in oxalic acid showed a strong PL peak in the blue. Due to an obvious asymmetry, the PL peak can be Gaussian divided into two bands around 405 and 455 nm, having a slight shift with the sample formed in different ac...

On the basis of the systematic study on temperature dependence of photoluminescence (PL) properties along with relaxation dynamics we revise a long-accepted mechanism for enhancing absolute PL quantum yields (QYs) of freestanding silicon nanocrystals (ncSi). A hydrogen-terminated ncSi (ncSi:H) of 2.1 nm was prepared by thermal disproportination of (HSiO1.5)n, followed by hydrofluoric etching. R...

At the vacuum-ultraviolet (VUV) beam line of a synchrotron, an end station for photoluminescence (PL) coupled to a system to detect absorption is used to investigate the luminescence and absorption of materials. We analyzed a CVD diamond window in wavelength range 160 250 nm at 300 and 14 K. The PL excited with VUV light enabled an identification of nitrogen defects in diamond samples. The VUV ...

A charge neutral complex (CNC) was formed in aqueous solution by combining an orange light emitting anionic conjugated polyelectrolyte and a saturated cationic polyelectrolyte at a 1:1 ratio (per repeat unit). Photoluminescence (PL) from the CNC can be quenched by both the negatively charged dinitrophenol (DNP) derivative, (DNP-BS(-)), and positively charged methyl viologen (MV(2+)). Use of the...

The optical properties of alternating ultrathin Ti0.91O2 nanosheets and CdS nanoparticle hybrid spherical structures designed by the layer-by-layer (LBL) assembly technique are investigated. From the photoluminescence (PL) spectral measurements on the hybrid spherical structures, a spectrum-shifted fluorescence emission occurs in this novel hybrid material. The time-resolved PL measurements exh...

017402-1 We have found strong visible photoluminescence (PL) from 0.4 nm carbon nanotubes embedded in the ordered channels of a zeolite crystal matrix. The PL exhibits a broad emission band with an efficiency of 1%–5%. Strong polarization dependence is observed both on the excitation and emission, indicating a preferential optical dipole along the axis of carbon nanotubes. By correlating with t...

Quantum dot (QD) nanoclusters were formed using oppositely charged colloidal CdTe QDs, of two different sizes, mixed in aqueous solutions. The photoluminescence (PL) spectra and time-resolved PL decays show signatures of Förster resonant energy transfer (FRET) from the donor QDs to the acceptor QD in the nanoclusters. A concentration dependence of the donor QD lifetime is observed in mixed solu...

The effect of well width on both the photoluminescence (PL) and phonon emission in optically excited InGaN multiple quantum well (MQW) samples has been investigated. For narrow MQW samples (w < 2.5 nm), the lowtemperature PL quantum efficiency is close to unity with the phonon emission being due mainly to carrier relaxation in the QWs. For wider MQWs samples the PL quantum efficiency is reduced...

Biexciton photoluminescence (PL) quantum yields (Q(2X)) of individual CdSe/CdS core-shell nanocrystal quantum dots with various shell thicknesses are derived from independent PL saturation and two-photon correlation measurements. We observe a near-unity Q(2X) for some nanocrystals with an ultrathick 19-monolayer shell. High Q(2X)'s are, however, not universal and vary widely among nominally ide...