Synchrotron-based X-ray absorption spectroscopy of Pd nanoparticles decorated on multi-walled carbon nanotubes during successive cycles of He/H2 exposure.

The MWCNTs are decorated by Pd nanoparticles via various techniques including laser ablation in liquid, chemical reduction, and simultaneously both of them. To study the hydrogen adsorption mechanism, Pd K-edge X-ray absorption spectroscopy (XAS) is carried out via heating/cooling processes under He/H2 exposure. The Fourier transform X-ray absorption fine structure (FT-EXAFS) simulation indicates the presence of the Pd-Pd and Pd-C(O) bonds. Furthermore, during the successive cycles of He/H2 exposure, bond restructuring takes place. Moreover, the heating process under He/H2 exposure induces a destructive effect on the Pd-C(O) links. Furthermore, the Pd-Pd bond distance enlarges due to the hydrogen adsorption for all samples, however, in the case of PLAL, the change in the bond distances becomes dominant. XRD and XPS are applied to support the findings.

Laser induced fluorescence spectroscopy of various carbon nanostructures (GO, G and nanodiamond) in Rd6G solution.

The effect of carbon nanostructures such as graphene (G), graphene oxide (GO) and nanodiamond (ND) on the spectral properties of Rhodamine 6G (Rd6G) emission due to the laser induced fluorescence (LIF) was investigated. It is shown that the addition of carbon nano- structures lead to sensible Red/Blue shifts which depend on the optical properties and surface functionality of nanoparticles. The current theories such as resonance energy transfer (RET), fluorescence quenching and photon propagation in scattering media support the experimental findings. Stern-Volmer curves for dynamic and static quenching of Rd6G molecules embedded with G, GO and nanodiamond are correlated with spectral shifts. Furthermore, time evolution of the spectral shift contributes to determine loading/release rates of fluorescent species with large S-parameter on the given nano-carriers.

Red/blue spectral shifts of laser-induced fluorescence emission due to different nanoparticle suspensions in various dye solutions.

Red/blue shifts of laser-induced fluorescence (LIF) are investigated using several guest dielectric nanoscatterers, such as TiO2, ZnO, Al2O3, and SiO2, in the host Rd6G, RdB, Coumarin 4, and Coumarin 7 ethanolic solutions. A couple of inflection points are identified varying nanoparticle (NP) density into dye solutions based on LIF spectroscopy. The inflection of the spectral shift exhibits that the suspension of NPs in dye solutions significantly involves a couple of competitive chemical and optical mechanisms during photon traveling in scattering media regarding ballistic and diffusive transport. It is shown that the low, medium, and high NP additives in fluorescent suspension induce blue, red, and blue spectral shifts, respectively.