Selective excitation of surface-enhanced secondary emission from biomolecules by substrates based on thin golden films

Thin (5–30 nm) golden films have been derived by vacuum deposition of gold onto dielectric substrates and subsequent annealing at temperatures of 200–350°C. These films allow selective detection of the desired component (fluorescence or Raman scattering) of the surface-enhanced secondary emission from the same resonantly driven molecule.     

Vibrational spectra of AuF5 complexes with nitrogen fluorides and oxofluorides

Vibrational spectra and structural features of AuF₅ complexes with nitrogen fluorides (NF₃, N₂F₄) and oxofluorides (FNO, NF₃O) are investigated. Vibrational frequency assignment in the solid phase and in solution of anhydrous HF was made. Distinctive features of vibrational spectra of X⁺AuF₆ ^? (X = NF₄ ⁺, N₂F₃ ⁺, NO⁺, NOF₂ ⁺) related to structural transformations of cations and hexafluoroaurate anion due to the influence of the crystal field and cation-anion interactions are discussed.     

Structure of simple and complex noble gas fluorides

The structural parameters of simple and complex fluorides of noble gases in different aggregate states have been analyzed. The data on their molecular and crystal structure are reported. The structural features of simple, coordination, polymer, and clathrate-like compounds of krypton and xenon fluorides are considered     

Optical Properties of Quantum Dots with a Core–Multishell Structure

JETP Letters - In the last decade, colloidal semiconductor nanocrystals (quantum dots) have been not only studied fundamentally but also applied in photovoltaics, optoelectronics, and biomedicine....     

Resonant transfer of one- and two-photon excitations in quantum dot–bacteriorhodopsin complexes

Light-sensitive protein bacteriorhodopsin (BR), which is capable of electrical response upon exposure to light, is a promising material for photovoltaics and optoelectronics. However, the rather narrow absorption spectrum of BR does not allow achieving efficient conversion of the light energy in the blue and infrared spectral regions. This paper summarizes the results of studies showing the possibility of extending the spectral region of the BR function by means of the Förster resonance energy transfer (FRET) from CdSe/ZnS quantum dots (QDs), which have a broad spectrum of one-photon absorption and a large twophoton absorption cross section (TPACS), to BR upon one- and two-photon excitation. In particular, it is shown that, on the basis of QDs and BR-containing purple membranes, it is possible to create electrostatically associated bio-nano hybrid systems in which FRET is implemented. In addition, the large TPACS of QDs, which is two orders of magnitude larger than those of BR and organic dyes, opens up a means for selective two-photon excitation of synthesized bio-nano hybrid complexes. On the basis of the results of this work, the spectral region in which BR converts the light energy into electrical energy can be extended from the UV to near-IR region, creating new opportunities for the use of this material in photovoltaics and optoelectronics.     

Diode laser measurements of the first overtone HF lineshape broadened by Ar,Xe, Kr and N2

A high-resolution spectroscopy study of the HF first overtone vibrational–rotational 0–2 R(0) line profile was carried out in Ar, Xe, Kr and N₂ gas mixtures using near-IR tunable diode laser. The HF 0–2 R(0) analytical line is known as the most appropriate for laser detection of HF molecules in the atmosphere. Highly accurate collisional broadening, shift and “narrowing” coefficients were determined from the direct spectroscopic fit employing traditional Voigt, Rautian and Galatry symmetric profiles and using an asymmetric speed-dependent Voigt profile. These data make the information of modern spectroscopic databases, e.g., HITRAN2012, much more exact. A noticeable line shape asymmetry was investigated in detail. In this paper, the validity of the use of model profiles in spectroscopic fitting is severely discussed. For the first time, we draw attention to the need for physically realistic line shape models to avoid systematic errors in retrieved gas concentrations. We stress that in the case of HF, all considered model profiles serve only as ad hoc models; they may conceal the true physics of spectral line formation.     

Reaction of Microcrystalline Cellulose with Water

The properties of microcrystalline cellulose prepared by classical (thermohydrolytic) and nonclassical (UHF) treatment of cotton cellulose are compared. The mechanisms of its reaction with water were studied to obtain stable gelatinous suspensions.