Effect of conformational rigidity on the glass transition and initial decomposition temperatures of polyimides

The dependence of the glass transition and initial decomposition temperatures of polyperyleneimide and polynaphthylimide on the conformational rigidity was studied by the Monte Carlo, Kuhn segment, and quantum chemical AM1 methods. The corresponding linear plots can be used for estimation of the glass transition and initial decomposition temperatures when experimental determination is difficult.     

Interaction of sorbed Ni(II) ions with amorphous zirconium hydrogen phosphate

Samples of amorphous zirconium hydrogen phosphate with different zirconium and phosphorus concentrations in hydrogen and nickel-substituted forms are studied by means of electronic, ³¹P NMR, and impedance spectroscopy. It is shown that Ni(II) → H⁺ ion exchange is accompanied by the hydrolysis of sorbed cations and the formation of complexes with the dihydro- and hydrophosphate groups of the inorganic ionite. It is found that the coordination environment of Ni(II) in the sorbent phase includes 2–4 fragments of phosphate groups, along with OH groups and water molecules.     

Correlation between the Optical Properties and Structure of GRS-Active Substrates Based on Silver Films

The relationship between the optical properties of GRS-active substrates based on silver films and the parameters of their surface roughness have been studied by methods of mathematical statistics (correlation, regression, and factor analyses). The equations of nonlinear regression connecting these quantities were obtained. It is established that most correlatable are the maximum value of the optical density with the distance between islands and with the coefficient of their shape, and also its relation to the halfwidth of the optical density band of a silver film with the mentioned characteristics of the islands.     

Influence of Thermal Annealing and Deposition Conditions on the Structure and Optical Properties of GRS‐Active Substrates Based on Silver Films

Using the methods of atomicforce microscopy, xray diffractometry, and spectrophotometry, we have studied the morphological, structural, and optical characteristics of GRSactive substrates based on original and annealed silver films. We show that the backing temperature during deposition is the factor which exerts the most substantial effect on the morphological and optical properties of silver films and also on their stability with time. The coefficients of the correlation of the deposition rate with the characteristics of the optical density spectra of silver films are calculated. It is found that hightemperature (350°C) annealing of a silver film leads to the selforganization of its surface into a quasiperiodic structure with semiellipsoidal islets. The contribution of the processes of excitation of plasma resonances to the formation of the optical density spectra is discussed. It is shown that as a result of thermal modification the concentration of the crystalline phase of silver in a silver film increases 2–3 times and also the dispersion of the orientation of crystallites decreases.     

A hyper-raman spectroscopy,spectrophotometry, and atomic force microscopy study of photochromism of spirocyclic compounds on nanostructured metal films

The specifics of photochromic transformations of spirocyclic molecules at the nanostructured metal surface were studied by hyper-Raman spectroscopy (HRS) and spectrophotometry. Unique nanostructured systems were prepared, and their surface morphology and optical properties were examined. Enhancement of the photochromic transformations near the nanostructured metal surface was revealed. HRS spectra for various classes of spirocyclic compounds adsorbed on nanostructured systems of different types (granular silver films, AgCl-Ag films) were measured. The bands due to in-plane vibrations have the highest intensity, thereby indicating preferred planar geometry of adsorption of the test molecules.     

Photochromic Properties and Surface Enhanced Raman Scattering Spectra of Indoline Spiropyran in Silver-Based Nanocomposite Films

The structure and photochromic transformations of composite organometallic nanosystems composed of Ag nanoparticles covered with a layer of indoline-spiropyran (ISP) molecules from solutions were studied by spectrophotometry, surface Raman scattering spectroscopy (SERS) and quantum chemistry. Analysis of experimental data showed that studied nanostructured systems have photochromic properties, manifested in the reversible photo-induced changes both of the electronic-absorption spectra and of the relative intensity of the SERS bands. The open form of ISP, formed in the organometallic nanostructured film as a result of photochromic transformations, has an adsorption geometry, and, possibly, a conformation different from that formed as a result of chemisorption of ISP molecules on silver colloids.     

Structural Thermo‐ and Phototransformations of Oxaindane Spiropyrans Adsorbed on Silver Films

Using giant Raman scattering spectroscopy methods, we have studied the structure and also the thermo and phototransformations of dimethylphthalanspirobenzopyran (PhSBP) adsorbed on the surface of silver films. It is shown that on adsorption of PhSBP from ethanol solutions, on the surface of the silver films there are predominantly open forms of molecules which do not exhibit photochromic properties. It is established that cooling of the specimen to 77 K initiates thermoreversible reconstruction of the adsorption layer with formation of the aggregates of the PhSBP molecules. These reversible structural changes in frozen specimens are enhanced on exposure to the light of a visible range.     

Photoinduced Modulation of the Emission from СdSe/ZnS Quantum Dots by Photochromic Transformations of Diarylethenes

Crystallography Reports - A spectral study of the interaction between the molecules of photochromic compounds of the diarylethene class and CdSe/ZnS quantum dots (QDs), in dependence of the...     

Generation of a Photoacoustic Response of a Two-Layer Polymer/Gel Structure

Technical Physics - Generation processes of a photoacoustic response of a layered polyethylene/hydrogel structure by its irradiation with periodically modulated light have been experimentally...