Second-harmonic generation (SHG) microscopy is a label-free imaging method that can be used to visualize the detailed arrangement of collagen structures in biological tissues. Here, we sought to optimize the speed of microscopic SHG image acquisition of macroscopic fixed tissue sample areas by employing the wide-field imaging with a high power and medium, 1 MHz pulse repetition frequency laser in combination with a mechanical sample scanning. Unlike in the conventional laser-scanning microscopy, the optimum of the wide-field acquisition entails an interplay between the size of the illuminated area and the intensity of the generated signal. We delineate quantitative procedures to set the image parameters for the maximum speed of the tiled image acquisition, and also describe the possible optimization of the laser parameters for further enhancement of the speed of acquisition.

Theranostics is the emerging field of medicine that uniquely combines diagnostic techniques and active agents to diagnose and treat medical conditions simultaneously or sequentially. Finding a theranostic agent capable to cure the affected cells and being safe for the healthy ones is the key for successful treatment. Here, we demonstrate that agglomerated single-walled carbon nanotubes (SWCNTs) are promising theranostic agent that enables photo-activated ‘cold’ destruction of the cancer cells keeping their environment alive. The absorption of picosecond pulses by SWCNT agglomerates results in the mechanical (due to photoacoustic effect) rather than photothermal cancer cell destruction, which was visualized by micro-Raman and ultrafast near-infrared CARS. The developed theoretical model allows us to distinguish photothermal, photoacoustic, and photothermoacoustic regimes of the cancer cell destruction, and also to optimize SWCNT-based theranostics recipe.

The present work continues the analysis of results of Dementjev et al. (2015) in order to identify the interlayer interactions of the pi-bands. Analysis of the N(E) C KVV Auger spectra of highly-ordered pyrographite showed the absence of the electron exchange between the pi-bands in 1-6 layers. Since the pi-bands are formed by the p(z) -> pi transitions, one can suggest that the pi-band occupation at each graphene layer is formed by the p(z)-electrons of this layer. Since the p(z), electrons belong to the sigma(p)-bands, the p(z) -> pi transitions in the sigma(p-)bands in each of 2-6 graphene layers result in formation of holes H, whose concentration is equal to the concentration of electrons in the pi-bands [H-i] [pi(i)]. This shows the origin of the ambipolar conductivity in graphene.The absence of the electronic interaction between the pi-bands allows a suggestion that the interaction between top six graphene layers is due to the van der Waals electrostatic attractive forces. These forces promote the p(z) -> pi transitions in each of the 2-6 graphene layers and depend on the number of graphene layers above. The N(E) C INV Auger spectra allow identification of number (1-6) of graphene layers and the pi-band occupation at each of the layer. For the first time a specification of the van der Waals forces in HOPG was done. (C) 2016 Elsevier B.V. All rights reserved.

N(E) C KVV Auger spectra (V= sigma(s)sigma(p)pi) were used for measurement of the pi-band electron occupation of five outer layers on freshly cleaved bulk HOPG. The pi-band electron occupation of the 1-5 graphene layers was measured relative to the electron concentration in the sigma(p)-band. In-depth pi-band profiles were obtained by means of variation of the Auger electron takeoff angle within the range of 15-90 degrees. Differences in the pi-band electron occupation of the 1-5 graphene layers were determined. The pi-band electron occupation varies from 0 at the top graphene layer to that of the pi-band electron occupation typical for bulk HOPG at the 5th graphene layer counted from the outer surface. These results are discussed on the basis of the pi-band formation under the interlayer interaction of the p(z)-electrons. (C) 2015 Elsevier B.V. All rights reserved.

This work describes application of coherent anti-Stokes Raman scattering (CARS) microscopy technique for analytical characterization of microstructured materials based on chitosan. We demonstrate that nitrogen-hydrogen vibration band in the high wavenumber region of CARS spectrum prevails over response from oxygen-hydrogen vibrations and can be used as a spectral marker of chitosan. The chemically selective imaging is experimentally demonstrated by applying CARS microscopy to discriminate between chitosan and polystyrene microparticles. CARS microscopy was shown to be a valuable tool for characterization of polluted chitosan fibre from utilized engine filter material. A possibility to observe foreign material pieces on the surface of the polluted chitosan fibre is demonstrated and discussed.

MICROSTRUCTURE PECULARITIES OF VVER-1000 REACTOR PRESSURE VESSEL MATERIALS FRACTURE SURFACES M.A. Saltykov, O.O. Zabusov, B.A. Gurovich, M.A. Artamonov, A.P. Dementjev, E.A. Kuleshova, S.V. Fedotova, D.A. Zhurko The experimental data are presented on determination of phosphorus segregation on grain boundaries and precipitation surfaces located on grain boundaries of VVER-1000 reactor pressure vessel (RPV) materials subjected to continuous thermal exposures using Auger-electron spectroscopy. The influence of precipitates on the brittle transgranular fracture of an irradiated VVER-1000 RPV weld metal is shown. Auger peaks fine structure of carbon on grain boundaries was carried out, a qualitative evaluation of carbon role in the brittle intergranular fracture mechanism is presented.

We demonstrate the capabilities of the coherent anti-Stokes Raman scattering (CARS) microscope and its multimodal operation to image a histological section of human intestinal tissue. The imaging of unstained and stained sections using various nonlinear optical contrasts was performed. The CARS configuration of our mi croscope allows probing which does not require a preliminary staining of tissue saving the treatment time and providing label-free investigation of original matter. Particular attention was paid to visualisation of unstained tissue. CARS images were recorded in the high wave number Raman spectroscopy region and the spectra of the most distinguished features of images are provided and discussed. Additionally, the two photon excitation fluorescence (TPEF) and second harmonic generation (SHG) contrast mechanisms were used for structural visualisation of both unstained and stained sections of human intestinal tissue. Visualisation of a histological section using all contrast mechanisms mentioned above is analysed and discussed. The research is aimed to draw attention to a potential of CARS/nonlinear microscopy in routine healthcare.

Identification of intermediate and final products of the chemical reaction that produces nanodiamond particles is a key factor in understanding its mechanism. In this work different nanodiamond samples were studied before and after chemical cleaning by X-ray photoelectron and Auger spectroscopy. It was found that the chemical state of carbon atoms is the same before and after chemical cleaning. We find that the carbon atoms are sp(3)-bonded inside nanodiamond particles and have a new, unique chemical state on the surfaces. The latter differs significantly from sp(2)- and sp(3)-bonded carbon and can be figured as the valence band near the Fermi level being occupied by three electrons.

Electrical resistance of films made of the source material and purified HiPCO and Arc single-walled carbon nanotubes (SWCNTs) with a thickness of 20−40 μm is 2.4 to 45 Ω (electrical conductivity of 0.42 × 10 3 to 5.03 × 10 3 S/m) at room temperature. The films have been formed by vacuum microfiltration of SWCNT suspensions in toluene and characterized by Raman and X-ray photoelectron spectroscopy and scanning electron microscopy. The conductivity of the films at room temperature depends on the type and degree of purity of the material of nanotubes. The resistance of the films decreases with the increasing temperature over the range of 4.2–290 K, and the rate of the step-down decreases with increasing purity of the material of the nanotubes. The conductivity of the films is semiconducting in character, and the electron transport is consistent with three-dimensional hopping conductivity.

Fluorescence spectra and kinetics of poly(2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylene vinylene) (MEH‐PPV)/MCM41 silica composite have been analyzed at different temperatures and compared with fluorescence properties of MEH‐PPV solutions and spin coated films. As follows from this comparison, the composite possesses significantly wider fluorescence spectra, longer fluorescence relaxation and weaker temperature dependence of its intensity. These peculiarities are explained in terms of the reduced exciton diffusion and an increased torsional disorder of polymer chains embedded in pores.

We present a coherent anti-Stokes Raman scattering (CARS) microscope based on a robust and simple laser source. A picosecond laser operating in a cavity dumping regime at the 1MHz repetition rate was used to pump a traveling wave optical parametric generator, which serves as a two-color excitation light source for the CARS microscope. We demonstrate the ability of the presented CARS microscope to measure CARS spectra and images by using several detection schemes.

Transient absorption of silicate glasses doped with PbS nanocrystals has been investigated in a wide excitation intensity range. We demonstrate that the absorption bleaching is in strong competition with the excited state absorption. At low excitation intensities when only one electron–hole pair per nanocrystal is created, the excited state absorption weakens the bleaching of the lowest energy absorption band and causes an induced absorption at higher photon energies. At high excitation intensities when four times degenerated excited states are completely occupied, the excited state absorption shifts to the low energy side and the absorption bleaching in the spectral region of the lowest exciton band turns into the induced absorption. The induced absorption is related to the high density of carrier trapping states created during the nanocrystal growth in a glass matrix, the most probable mechanism being the influence of the trapped carrier electric field on energies of biexcitonic transitions.

Exciton relaxation kinetics of poly(di- n -hexylsilane) (PDHS) confined within 10-nm size pores of silica matrix SBA-15 was investigated by frequency domain fluorometry in the 10–300 K temperature range. Temperature independent exciton lifetimes of 0.66 ns and 0.28 ns were determined for the PDHS in the aggregated form (up to 300 K) and in trans form (up to 200 K), respectively, indicating the constant luminescence quantum yield and the temperature insensitive nonradiative relaxation upon confinement of PDHS into nanopores. The absence of thermal activation of nonradiative decay is most likely caused by severely restricted exciton migration towards quenching centers in low-dimensional structures.

Temperature independent exciton lifetimes, determined for the poly(di-n-hexylsilane) in the aggregated form and trans form, indicate the constant luminescence quantum yield and the temperature insensitive nonradiative relaxation upon confinement of PDHS into nanopores.

Photoluminescence and photoluminescence excitation spectra of nanosize poly(di-n-hexylsilane) embedded in the SBA-15 with 6 nm diameter pore were investigated in the temperature range of 10–290 K. We clearly demonstrate the thermochromic transition at 265 K between trans- and gauche- conformations of an isolated polymer chains embedded in the nanoporous material. Existence of the polymer chain having trans-conformation in a separate pore of 6 nm diameter was prooved. The location and packing of the polymer chains in this pore was simulated using the quantum chemistry calculations in the cluster approximation. The investigation of the polarized luminescence dynamics of the nanosize polymer with pore diameters of 6 and 10 nm has shown that the polymer chains are aligned by embedding.

The reaction of thin multiwalled carbon nanotubes with a mixture of concentrated HNO3 and H2SO4 has been studied by IR absorption and x-ray photoelectron spectroscopies. The results indicate the attachment of-C(O)OH groups to nanotubes and subsequent conversion of these groups to-C(O)Cl groups via reaction with SOCl2 and then to-C(O)NR2 via reaction with didodecylamine. The yield of the carboxylated nanotubes is 53%, and that of the amidated nanotubes is 28%. The O:C atomic ratio in the carboxylated tubes is 1.0:9.0. The solubility of the carboxylated tubes in water is 3.13 g/l, and that of the amidated tubes in chloroform is 1.30 g/l.

XPS, EEL, Auger and FTIR spectroscopies were used to testify the influence of chemical treatment upon the state of C-atoms in the core and on the surface of nanodiamond particles. The study was carried out with ND (JSC "Diamond Centre"). The different kinds of treatments were done ex-situ: with air (5 h) at 200 and 400 degrees C; with hydrogen (5 h) at 800, 850 and 900 degrees C; with fluorine (48 h) at 20 degrees C and 0.5 atm. Noticeable change was not found in the state of C-atoms both on the surface and up to 10 monolayers after these treatments. The concentration of F in the sample is equal to similar to 9 at.%. The binding energy of the F 1 s differs from the one in functional groups- -CF2, -CF. Nevertheless FTIR spectra show bands that can be related to C-O, C-F bonds. (C) 2007 Elsevier B.V. All rights reserved.

Excited state relaxation kinetics of nanostructured poly(di-n-hexyl)silane embedded in nanoporous silica SBA-15 with the pore size of 10 not was considered with the nanosecond and picosecond time resolution by using photomultiplier with fast response time and by means of time correlated two-pulse excitation. Measurements were carried out at room temperature. For comparative reasons the exciton relaxation kinetics of poly(di-n-hexyl,)silane films are also considered. It teas found that the photoluminescence of nanostructured poly(di-n-hexyl)silane decays exponentially with about 6ns time constant, which is more than 10 times longer than that of the film.. The longer decay time should be related with slower exciton diffusion and lower density of exciton quenching centers.

Photoluminescence and photoluminescence excitation spectra of poly(di-n-hexylsilane) (PDHS) embedded in nanoporous silica material SBA-15 with a pore diameter of 10 nm were analyzed at different temperatures ranging from 5 to 320 K. The optical spectra of this composite are structured containing three bands, attributed to different structural forms of the polymer coexisting in a restricted pore volume: the polymer chains in the trans and gauche conformations, and their aggregates. Different structural forms are spatially separated and weakly coupled; therefore, several bands are distinguished in the photoluminescence spectra at low temperatures when several forms coexist. For the first time two termochromic transitions of nanosize PDHS were observed at about 265 and 320 K for a single polymer chain and for aggregates, respectively.