Assembling Near-Infrared Dye on the Surface of Near-Infrared Silica-Coated Copper Sulphide Plasmonic Nanoparticles.

Functionalization of colloidal nanoparticles with organic dyes, which absorb photons in complementary spectral ranges, brings a synergistic effect for harvesting additional light energy. Here, we show functionalization of near-infrared (NIR) plasmonic nanoparticles (NPs) of bare and amino-group functionalized mesoporous silica-coated copper sulphide (CuS@MSS and CuS@MSS-NH) with specific tricarbocyanine NIR dye possessing sulfonate end groups. The role of specific surface chemistry in dye assembling on the surface of NPs is demonstrated, depending on the organic polar liquids or water used as a dispersant solvent.

Impact of the thermal properties of the environment on the hot-band absorption-assisted single-photon upconversion.

Single-photon hot-band absorption-assisted anti-Stokes photoluminescence (ASPL) is a non-equilibrium process which causes a local cooling effect and which therefore is accompanied by a reverse heat flux from the warmer environment. Here, we demonstrate that the thermal properties of the medium, , its thermal conductivity and specific heat capacity, play a significant role in driving the ASPL of an emitter placed in it. Exploiting seven different solvents and the near-infrared tricarbocyanine dye as a single-photon upconverter, we show an obvious correlation of activation energy and the quantum yield (QY) of ASPL with the solvent thermal conductivity and specific heat capacity, respectively.

"Awakening" of the S Emission of Tricarbocyanine Dyes Stimulated by Interaction with Carbon Quantum Dots.

Anti-Kasha emission (i.e., the emission from S ( > 1) excited levels) of infrared chromophores which possess intensive absorption and S emission in the near-infrared region, but which are spectrally silent in the visible, is a challenging task for relevant applications such as energy conversion, bioimaging, sensitization of solar cells, optical sensors, and so on.

Dynamics of Excitons in Conjugated Molecules and Organic Semiconductor Systems.

The exciton, an excited electron-hole pair bound by Coulomb attraction, plays a key role in photophysics of organic molecules and drives practically important phenomena such as photoinduced mechanical motions of a molecule, photochemical conversions, energy transfer, generation of free charge carriers, etc. Its behavior in extended π-conjugated molecules and disordered organic films is very different and very rich compared with exciton behavior in inorganic semiconductor crystals. Due to the high degree of variability of organic systems themselves, the exciton not only exerts changes on molecules that carry it but undergoes its own changes during all phases of its lifetime, that is, birth, conversion and transport, and decay.

Low-Temperature Reduction of Graphene Oxide: Electrical Conductance and Scanning Kelvin Probe Force Microscopy.

Graphene oxide (GO) films were formed by drop-casting method and were studied by FTIR spectroscopy, micro-Raman spectroscopy (mRS), X-ray photoelectron spectroscopy (XPS), four-points probe method, atomic force microscopy (AFM), and scanning Kelvin probe force (SKPFM) microscopy after low-temperature annealing at ambient conditions. It was shown that in temperature range from 50 to 250 °C the electrical resistivity of the GO films decreases by seven orders of magnitude and is governed by two processes with activation energies of 6.22 and 1.

Excimer Emission in J-Aggregates.

An excimer in J-aggregates has been often considered as a self-trapped exciton originating from the free exciton excited on the same aggregate and relaxed through interaction with vibronic modes. Here we show that other types of excimers due to intermolecular off-diagonal interactions can be observed in J-aggregates of thiamonomethinecyanine dyes. These excimers arise owing to free excitons too, but they possess a longer formation time of more than 100 ps, indicating migration of free excitons to the excimer formation site, where they interact with a guest species in the ground state.

Stomach Cancer: Interconnection between the Redox State, Activity of MMP-2, MMP-9 and Stage of Tumor Growth.

High levels of reactive oxygen (ROS) and nitrogen (RNS) species can lead to the destruction of extracellular matrix facilitating tumor progression. ROS can activate matrix metalloproteinases (MMP), damage DNA and RNA. Therefore, the levels of MMP, ROS and RNS can serve as additional prognostic markers and for the estimation of the effectiveness of tumor therapy.

Sensitive coating for water vapors detection based on thermally sputtered calcein thin films.

In this paper the adsorption properties of thermally sputtered calcein thin films towards water and other polar molecules vapors are studied by different characterization techniques: quartz crystal microbalance, surface plasmon resonance and visible spectroscopy. Sensitivity of calcein thin films to water vapors resulted much higher as compared with those of a number of dyes whose structure was close to that of calcein. All types of sensors with calcein coatings have demonstrated linear concentration dependences in the wide range of water vapor pressure from low concentrations up to 27,000 ppm (close to saturation).