Infrared absorption spectra and structure of TiO2-SiO2 composites

The composites xTiO₂-(1−x)SiO₂ (x = 0.1, 0.5, 0.9) were obtained by coprecipitation from solutions of alkoxides: tetraethoxysilane (TEOS) and titanium tetraisopropoxide (TIPT). Intermolecular interaction of the components of the composite is apparent in the IR absorption spectra in the 928–952 cm⁻¹ region, and is connected with bending vibrations of the Si-O-Ti bond. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 724–728, September–October, 2008.     

Modification of electronic properties during adsorption of conjugate organic molecules on the surface of polycrystalline SnO<Subscript>2</Subscript>

The modification of the electronic structure during adsorption of ultrathin copper phthalocyanine (CuPc) and 3, 4, 9, 10 perylene-tetracarboxylic-dianhydride (PTCDA) coatings on the surface of polycrystalline tin dioxide is traced. Auger electron spectroscopy is employed to find changes in the atomic composition of the surface. It is found with the help of low-energy electron total current spectroscopy using a testing beam of electrons with energies up to 30 eV that the total current spectra typical of organic films are formed when the thickness of the coating being deposited is 2–7 nm. The formation of an interface layer 1.5–2.0 nm in thickness is detected, in which the intensity of the structure of the total current spectra decreases and the effect of interaction of PTCDA molecules with the SnO₂ surface is manifested.     

Experimental and theoretical investigation of vibrational spectra of copper phthalocyanine: polarized single‐crystal Raman spectra,isotope effect and DFT calculations

The IR‐ and Raman spectra of copper phthalocyanine (CuPc), as well as the isotopic wavenumber shifts upon ¹⁵N substitution in CuPc, were investigated experimentally and theoretically. The symmetry of molecular vibrations was determined using polarized Raman spectra of an oriented CuPc single crystal. Density functional theory (DFT) calculations were used for the detailed assignment of different bands in the vibrational spectra of CuPc. Theoretically predicted geometry, wavenumbers and isotopic shifts are in a very good agreement with the experimental values. A comparison of experimentally obtained isotopic shifts with theoretical predictions allowed us to reveal some characteristic features of normal vibrations of CuPc molecule. Copyright © 2009 John Wiley & Sons, Ltd.     

Polymer gate dielectrics with self-assembled monolayers for high-mobility organic thin-film transistors based on copper phthalocyanine

Organic thin-film transistors based on polycrystalline copper phthalocyanine (CuPc) were fabricated by using poly(vinyl alcohol) as gate dielectric. After treatment of the gate dielectric using an octadecyltrichlorosilane self-assembled monolayer, a mobility of up to 0.11 cm²/V s was achieved, which is comparable to that of single-crystal CuPc devices (0.1–1 cm²/V s). The surface morphology was analyzed and the possible reasons for the enhanced mobility are discussed.     

Calculation of polarized IR absorption spectra for trans-1,4-polyisoprenes of various conformations

Polarized IR spectra for two conformations of trans-1,4-polyisoprene (α-and β-gutta-percha) were calculated. The IR dichroism of the absorption bands was calculated for both conformations. The computed results for polarized IR spectra and IR dichroism agree reasonably well with the respective experiment data. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 470–475, July–August, 2008.     

IR Spectroscopic signs of malignant neoplasms in the thyroid gland

We use Fourier transform IR spectroscopy to study thyroid tumor tissues which were removed during surgery. The IR spectra of the tissues with pathological foci are compared with data from histologic examination. In the region of N–H, C–H, and C = O stretching vibrations, the IR spectra of the tissues for thyroid cancer are different from the IR spectra of tissues without malignant formations. We identify the spectral signs of thyroid cancer. We show that IR analysis is promising for identification of thyroid pathology at the molecular level.     

Infrared spectra of brassinolide and castasterone steroid phytohormones and their 24-epi derivatives

Absorption bands in IR spectra of brassinolide, castasterone, and their 24-epi derivatives in the frequency range 3800–1000 cm^–1 have been interpreted. A number of spectral features distinguishing brassinolide from castasterone have been found. The conducted analysis shows that the structural differences manifest themselves in IR spectra of the investigated brassinosteroids in the region of stretching vibrations of CO–H, C=O, C–OH, C–O–C, CH₃, CH₂, and CH groups. The main distinctions in IR spectra of brassinolides and castasterones are due to the B ring structure.     

Low-temperature scanning tunneling microscopy and near-edge X-ray absorption fine structure investigation of epitaxial growth of F<Subscript>16</Subscript>CuPc thin films on graphite

Low-temperature scanning tunneling microscopy (LT-STM) and near-edge X-ray absorption fine structure (NEXAFS) measurements are used to study the epitaxial growth and molecular orientation of organic thin films of copper hexadecafluorophthalocyanine (F₁₆CuPc) on highly oriented pyrolytic graphite (HOPG). Our results show that F₁₆CuPc molecules lie flat on HOPG up to 5 nm thickness, stabilized by interfacial and interlayer π–π interactions. LT-STM experiments reveal the coexistence of two different in-plane orientations of the F₁₆CuPc monolayer on HOPG. On the second layer of F₁₆CuPc on HOPG, however, all F₁₆CuPc molecules possess the same in-plane orientation.     

Study of absorption spectra of gasolines and other hydrocarbon mixtures in the second overtone region of the CH<Subscript>3</Subscript>, CH<Subscript>2</Subscript>, CH groups

We have obtained experimental and model absorption spectra for individual hydrocarbons (toluene, benzene, n-heptane, and iso-octane) and their mixtures in the near IR range (λ = 1080–1220 nm). We model the spectra of nonsynthetic gasolines obtained under the same conditions by combining the spectra of three pure hydrocarbons. We show that the octane number of the studied gasoline is linearly related to the toluene (or benzene) concentrations in the model mixture. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 157–161, March–April, 2007.     

IR spectra temperature changes and conformational structure of 4-butyl-4′-cyanobiphenyl

IR spectra of 4-butyl-4′-cyanobiphenyl in the liquid and solid-crystal states were measured in the 400–4000 cm^–1 region at 28–70°C. Changes of the spectra as a function of temperature are due to the conformational fluxionality of the molecules according to calculated IR spectra of the possible 4-butyl-4′-cyanobiphenyl conformers. Calculations were carried out using the method of fragments and the LEV-100 program package. Bands sensitive to the conformational changes in the molecular structure were found. IR spectra have been interpreted. Conclusions have been made about the conformations of the sample in the solid-crystal and liquid phases. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 3, pp. 325–333, May–June, 2009.     

Effect of intravenous laser irradiation on the molecular structure of blood and blood components

We present the results of a spectral study of the effect of low-intensity laser radiation on the molecular structure of blood and blood components. Analysis of the Fourier transform IR absorption spectra of blood confirmed the changes we observed previously in the oxygen transport characteristics of blood with intravenous exposure to the emission from a He-Ne laser. We show that structural and conformational changes in the hemoglobin tetramer, initiated by laser-induced photoreactions between Hb and oxygen, lead to characteristic changes in the shape and intensity of the IR bands for NH stretching vibrations, and also the amide I and amide II absorption bands. In the IR spectra of irradiated blood samples, we note increased absorption in the bands for stretching vibrations of the phosphate groups (945–1280 cm⁻¹), which is evidence for an increase in the nucleic acid content (DNA, RNA). In the spectra of plasma and erythrocytes prepared from irradiated blood, there are no changes in this region of the IR spectrum. At the same time, in the IR spectra of samples of irradiated plasma, the intensity of the bands for stretching vibrations of the CH₂ groups increases substantially. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 106–112, January–February, 2006.     

Molar extinction coefficients of IR absorption bands of Cu(II) dipivaloylmethanate

IR absorption spectra of an intracomplex chelate compound of Cu(II) bis-dipivaloylmethanate in the spectral range 4000–300 cm⁻¹ are investigated. A comparison is made between the spectra of the complex in different aggregative states: as a solution in heptane and as condensed films. The molar extinction coefficients of absorption bands are calculated. The extinction coefficients found are used to evaluate the thickness of Cu(dpm)₂ films. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 34–37, January–February, 2000.     

Effect of a low-frequency magnetic field on the structure of globular blood proteins

We used IR Fourier absorption spectra of blood to study changes in the structure of globular blood proteins with extracorporeal autohemomagnetotherapy, used to treat ischemic heart disease. We compare the spectra of blood before and after magnetotherapy in the regions: amide I (1655 cm⁻¹), amide II (1545 cm⁻¹), amide III (1230–1350 cm⁻¹), amide IV and amide V (400–700 cm⁻¹). We have shown that pronounced changes in the spectra in the indicated regions on direct exposure of blood in vivo to a low-frequency pulsed magnetic field are connected with conformational changes in the secondary structure of globular blood proteins, which are apparent in the increase in the contribution of the α-helix conformation. We discuss the magnetotherapy-initiated appearance of new IR absorption bands at 1018 and 1038 cm⁻¹ and an increase in the intensity of a number of other bands located in the 1000–1200 cm⁻¹ region, which suggests a change in the concentration of some blood components. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 665–669, September–October, 2007.     

Infrared spectra of proteins and lipids in human breast malignant tissues

IR spectroscopy methods have been adopted for investigating resected tissues of mammary glands. IR spectra of surgical material are compared with histological data. Spectra of proteins and lipids in malignant tumors are shown to be different from those in benign tumors and in tissues outside the pathologically impacted volume. Differences in the protein spectra are due to changes in the supramolecular structure because of the cleavage of intramolecular C=O⋅⋅⋅H–N H-bonds. Spectral signatures of malignant pathologies are identified. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 2, pp. 261–266, March–April, 2009.     

Temperature influence on the intensity of water bands ν(OH) in IR spectra of some silicate minerals

An investigation is made of the temperature dependences of the intensities of bands ν(OH) in the IR spectra of talc, quartz, and muscovite under cooling-heating conditions in ranges of 93–300 and 300–673 K. In the 93–300 K range two types of water with reversible and irreversible temperature dependences of the absorption-band intensities in the IR spectra of these minerals are revealed. The types of bound water are separated in space, apply to the volume and surface of the minerals, and their absorption bands have temperature coefficients of intensity which differ in value and sign. Institute of Geology of the Karelian Scientific Center of the Russian National Academy of Sciences, 11, Pushkinskaya St., Petrozavodsk, 185610, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 124–127, January–February, 1999.     

IR spectrum of the closed form of indolinospironaphthooxazine

IR absorption spectra of indolinospironaphthooxazine (ISNO) are presented. The geometric structure and normal coordinates of the ISNO molecule have been calculated using a quantum mechanical DFT method. The IR spectrum of ISNO in its original spiro form has been interpreted for the first time. Four normal modes in the range 800–1200 cm^–1 with the largest amplitudes of C_spiro–O bond change are identified. The excited ISNO molecule spiro form may experience photoconversion to the merocyanine form through them.     

Infrared spectra of S-and R-isomers of biologically active brassinosteroids

Comparative analysis of IR spectra of S-and R-isomers differing in the configuration of OH groups in the side chain of biologically active 24-epi-and 28-homocastasterones and 24-epi-and 28-homobrassinolides is carried out. Stretching vibration frequencies of H-bonded OH groups of isomers of corresponding brassinosteroids practically coincide. The optical density in maxima of these bands is higher in spectra of the R-isomers. Alteration in the configuration of the OH groups weakly influences also the band intensities of CH3, CH₂, and CH groups. Band intensities of stretching vibrations of associated C=O groups of S-and R-isomers also neglibibly differ from each other. Their frequency characteristics do not experience substantial changes. These features differ considerably in IR spectra of castasterones and brassinolides. For castasterones, the difference in frequencies of band maxima of free and bound C=O groups amounts to ∼15 cm⁻¹; for brassinolides, 23 cm⁻¹. Intensities of both bands are approximately equal in spectra of castasterones. The band intensity of free C=O groups of brassinolides is considerably lower than that of H-bonded ones. The above spectral differences can be used to identify these brassinosteroids. Frequencies of both symmetric and antisymmetric deformation vibrations of CH₃ and CH₂ groups are close in spectra of all brassinosteroids studied. The frequency of CH₂ in a CH₂-OC group belongs only to brassinolides; of deformation vibrations of CH in a CH-C=O group, to castasterones. The frequency of stretching vibrations of C-O-C and C-O groups is observed only in spectra of brassinolides. In the region 1130–900 cm⁻¹ of IR spectra of brassinosteroids, stretching vibrations of CC, CCH, and C-OH groups are predominantly observed. In the frequency range 1130–995 cm⁻¹, the optical density of band maxima of S-isomers is higher than that of R-isomers, which can be used to identify isomers. At the same time frequencies of corresponding bands of isomers practically coincide. Differences in the structure of the side chain of brassinosteroids do not influence essentially the frequency characteristics of the IR spectra. The exception is the band related to stretching vibrations ν(C23-OH) of the side chain which features a considerable frequency ν_max ≈ 983 cm⁻¹ only in spectra of R-isomers of homocastasterone and brassinolide. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 623–630, September–October, 2008.     

Intermolecular interactions in acetonitrile in a liquid and in a low-temperature argon matrix

IR spectra of acetonitrile embedded in an argon matrix and in a liquid are recorded. IR spectra of specimens obtained with different concentrations of acetonitrile in argon are analyzed. The spectral region of C≡N vibrations of 2200–2300 cm⁻¹ with bands of monomers and possible associates is investigated. Overlap with the band of a hot transition on the low-frequency side is responsible for the pronounced asymmetry of the band ν(C≡N). To whom correspondence should be addressed. St. Petersburg State Institute of Precision Mechanics and Optics (Technical University), 14, Sablinskaya Str., St. Petersburg, 197101, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 627–631, September–October, 1999.     

Formation of color centers during growth of alkali-earth fluoride crystals

New bands within the ranges of 1900–2200 and 700–1000 cm^–1 have been discovered in the IR absorption spectra of crystalline alkali-earth fluorides. It is found that the defects responsible for the high frequency bands facilitate the formation of color centers during crystal growth. These bands are presumably caused by valence vibrations of CO molecules. The low frequency bands are attributed to molecular complexes which contain oxygen-vacancy dipoles.     

Application of reflection-absorption spectroscopy to quaternary solid solutions

In the present work the author describes a method for investigating phonon spectra of thin films of semiconductor solid solutions that is based on reflection-absorption spectroscopy in the far IR region. Analysis of spectra is carried out for two radiation polarizations (of the s- and p-type) and for the following experimental conditions: the spectral region 30–250 cm⁻¹ and an angle of incidence of 45°. By comparing theoretical and experimental spectra for quaternary solid solutions of Zn_xCd_yHg_1−x−yTe (ZCMT), the frequencies of LO- and TO-phonons are found and the three-mode behavior of the phonon spectra of ZCMT is established. Reported at the Second International Scientific and Technical Conference on Quantum Electronics, Minsk, November 23–25, 1998. Institute of Physics, Pedagogical University, 16A, Reitan Str., Rzeszów, 35–310, Poland. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 669–671, September–October, 1999.