Enhanced Raman Scattering in CVD-Grown MoS/Ag Nanoparticle Hybrids.

Surface-Enhanced Raman Spectroscopy (SERS) is a powerful, non-destructive technique for enhancing molecular spectra, first discovered in 1974. This study investigates the enhancement of Raman signals from single- and few-layer molybdenum disulfide (MoS) when interacting with silver nanoparticles. We synthesized a MoS membrane primarily consisting of monolayers and bilayers through a wet chemical vapor deposition method using metal salts.

Structural Defects Modulate Electronic and Nanomechanical Properties of 2D Materials.

Two-dimensional materials such as graphene and molybdenum disulfide are often subject to out-of-plane deformation, but its influence on electronic and nanomechanical properties remains poorly understood. These physical distortions modulate important properties which can be studied by atomic force microscopy and Raman spectroscopic mapping. Herein, we have identified and investigated different geometries of line defects in graphene and molybdenum disulfide such as standing collapsed wrinkles, folded wrinkles, and grain boundaries that exhibit distinct strain and doping.

Influence of aggregates and solvent aromaticity on the emission of conjugated polymers.

The influence of aggregates and solvent aromaticity on the photophysics and fluorescence dynamics of two conjugated polymers is studied. The two polymers are derivatives of poly(p-phenylene vinylene) (PPV) containing different kinked moieties along the main chain. The polymers contain 2,6-diphenylpyridine and m-terphenyl kinked moieties and they are abbreviated as PN and PC, respectively.

Study of the isotropic and anisotropic fluorescence of two oligothiophenes by femtosecond time-resolved spectroscopy.

The excited-state dynamics of two oligothiophenes, 5,5'-dicarboxyhaldehyde 2,2',5',2' '-terthiophene and 5-carboxyhaldehyde 2,2',5',2' '-terthiophene, were studied by time-resolved fluorescence spectroscopy, in the femtosecond regime. The isotropic and anisotropic parameters of their fluorescence were calculated. The angle (alpha) between the absorption and emission molecular dipoles was estimated from the initial fluorescence anisotropy.

Femtosecond time resolved fluorescence dynamics of a cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene).

A recently synthesized cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene) was studied by means of steady state and femtosecond time resolved upconversion spectroscopy in aqueous and EtOH solutions. Steady state spectroscopic measurements showed that the polymer emits at the blue-green spectral region and that aggregates are formed in concentrated polymer solutions. The fluorescence dynamics of the polymer in concentrated solutions, studied at a range of emission wavelengths, exhibited a wavelength dependent and multiexponential decay, indicating the existence of various decay mechanisms.