in this report, we present a facile approach for the synthesis of luminescent cds and cds:mn+2 nanocrystals by reaction of cdso4 and na2s2o3 in the presence of thioglycerol (c3h8o2s) as capping agent. the influence of various experimental variables including, ph values and percentage of dopant, on the growth rate and optical properties of the obtained cds nanocrystals has been systematically in...

Since graphene has no band gap, photoluminescence is not expected from relaxed charge carriers. We have, however, observed significant light emission from graphene under excitation by ultrashort (30-fs) laser pulses. Light emission was found to occur across the visible spectral range (1.7-3.5 eV), with emitted photon energies exceeding that of the excitation laser (1.5 eV). The emission exhibit...

Low temperature photoluminescence (PL) spectroscopy was used to evaluate CdTe single crystals grown by a vertical gradient freeze method. Materials suitable for xray detectors preparation were in the center of attention. Both usual above-gap-excitation and rarely used below-gap-excitation was employed to investigate native defects and impurities. Tunable Ti-sapphire laser was applied to study e...

In this work we report the synthesis and characterization of hybrid nanostructures of multiwall carbon nanotubes (MWCNT) and cadmium sulphide (CdS) nanoparticles. In a solution of thioacetamide and cadmium sulphide, purified MWCNT are added to prepare the CNT/CdS hetrostructure. XRD diagrams, SEM images, and also photoluminescence spectra of the prepared samples are analyzed. SEM images show th...

Photoluminescence study of undoped, doped GaN grown on (00.1), (11.0), (01.2)Αl 2 O 3 (100), (111)Si, and (00.1)6H—SiC substrates have been conducted. Strong bandedge emissions from all undoped samples and dopant-related emissions from doped samples were observed. Deep-level yellow emissioii centered around 2.2 eV was not observed from undoped GaN grown on 6H-SiC substrate, undoped GaN with opt...

We fabricated the black silicon (BS) structures by using nanosecond pulsed laser (ns-laser) in vacuum or in oxygen environment. It is interesting that the enhanced visible emission occurs in the photoluminescence (PL) spectra measured at room temperature and at lower temperature on the BS surface after annealing, in which lasing near 600 nm is observed on the BS surface with Purcell cavity stru...

Low temperature photoluminescence (PL) from InP1-xBix thin films with Bi concentrations in the 0-2.49% range reveals anomalous spectral features with strong and very broad (linewidth of 700 nm) PL signals compared to other bismide alloys. Multiple transitions are observed and their energy levels are found much smaller than the band-gap measured from absorption measurements. These transitions ar...

We studied the electrochemical and spectroscopic properties of a series of extended silole-based chromophores to understand the effect of structure on behavior. By changing the substituents attached to the chromophore, we observed large variations in luminescence quantum efficiency (ca. 0-0.6), lambdamax for absorbance and photoluminescence (PL), and radical ion stability. The differences are r...

We demonstrate that the gap states at the interface of Ca and a phenylene vinylene oligomer thin film are responsible for the dramatic quenching of its photoluminescence (PL). Upon oxidation of the Ca layer, the midgap states are removed, and the PL intensity recovers. From the cumulative Ca deposition and oxidation study, a 30 Å Ca oxide layer between the oligomer and the Ca metal prevents PL ...

Transition metal dichalcogenides, such as MoS2 and WSe2, have recently gained tremendous interest for electronic and optoelectronic applications. MoS2 and WSe2 monolayers are direct bandgap and show bright photoluminescence (PL), whereas multilayers exhibit much weaker PL due to their indirect optical bandgap. This presents an obstacle for a number of device applications involving light harvest...