Intramolecular photo-physical processes and spectral-luminescence properties of a dye merocyanine 540 and its complexes with water

Merocyanine 540 (M540) is famous dye that used in electronics and medicine. An important feature of the dye is a significant intramolecular transfer of the electron density in the excited state. Experimentally was investigated the electronic absorption and fluorescence spectra in different solvents M540. Electronic structure, spectra and rate constants of photo-physical processes of an isolated molecule and its complexes with water molecules were calculated by INDO method with spectroscopic parameterization. Analysis of the results allowed establishing the effect of individual fragments and hydrogen bonds with water on the electronic charge transfer between the terminal units in the state S1. Examination of photo-physical processes of decomposition of the fluorescent state was showed that the intramolecular processes of decay of the S1 state are not the cause of the differences calculated and experimental fluorescence quantum yield. Consideration of trans-cis photoisomerization leads to the elimination of this non-compliance. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Features of the synthesis of nanocollo id oxides by laser ablation of bulk metal targets in solutions

Laser ablation of bulk targets in a fluid — a promising new method for the synthesis of "pure" nanocolloids. Nanocrystalline materials produced by laser ablation are widely used in biology, medicine, and catalysis. High local temperature during ablation and large surface area of the particles promote chemical reactions and the formation of a complex composition of nanoparticles. In this paper the characteristics of the process of ablation and the obtaining of nanoparticles in a liquid by laser ablation of active materials (Zn, Ce, Ti, Si) were studied. Ways of increasing the productivity of laser ablation were discussed. Characterization of nanocolloids and nanocrystalline powders were performed. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Development of sers substrates based on nanoparticles obtained by pulsed laser ablation

SERS spectroscopy is an effective method for the determination of organic and biological compounds, which finds its place in many areas of human life: the analysis of works of art and food 24 YOUNG SCIENTISTS SESSION SESSION Y products, the identification of drugs and drugs, the study of biological structures, incl. at the cellular level. The creation of simple and effective SERS substrates is an urgent task in the development of this method. This paper presents the results of a study of SERS substrates based on gold nanoparticles (NPs). Gold NPs were obtained by pulsed laser ablation of an Au metal target in alcohol using a Nd:YAG laser (1064 nm, 7 ns, 150 mJ). The resulting colloidal solution was applied onto glass substrates by the drop method, varying the number of layers. The SERS characteristics were studied using a model dye rhodamine 6G using Renishaw inVia Basis Raman microscope. The samples were excited in the region of surface plasmon resonance of gold by laser radiation of 532 nm. The results of the study showed that with an increase in the number of deposited layers up to 5, the intensity of the Raman scattering of the dye increases linearly. With a further increase in the number of layers, the signal saturates. This data correlates with SEM data. At the beginning, an increase in the packing density of NPs in the plane of the substrate is observed. Accordingly, the number of "hot spots" increases, which contribute to the amplification of the signal. Further, the homogeneity of the NP layer deteriorates, and large bulk agglomerates appear. Thus, we have developed a simple method for obtaining SERS substrates, which made it possible to increase the signal intensity up to three orders of magnitude

Interface features and electronic structure of Bi2SiO5/β-Bi2O3 hetero-junction

Atomic and electronic structure of Bi2SiO5/β-Bi2O3 hetero-junction was described by means of density functional theory. The interface was found to be narrow-gap semiconductor with indirect band gap. The redistribution of states near the Fermi level in hybrid structure and the impact of spin-orbit coupling are discussed

Structure and optical properties of nanoparticles obtained by pulsed laser ablation of copper in gases

Nano-powders of different composition and structure were obtained by nanosecond pulsed laser ablation (Nd:YAG laser, 7 ns, 1064 nm, 20 Hz, 200 mJ) of a metallic copper target in a simple flow reactor at atmospheric pressure. The crystal structure, nanoparticles’ shape, and surface morphology were shown to depend on the gaseous media used (Air, Ar, N2, CO2). CuO nanopowders with a specific surface area 50 m2/g were synthesized by pulsed laser ablation in carbon dioxide and after annealing in air. The optical properties of the obtained powders were also investigated