Wyniki wyszukiwania - Biblioteka Nauki

1

Synthesis and characterization of polyaniline-polyvinyl chloride blends doped with sulfamic acid in aqueous tetrahydrofuran

100%

Ameen S. , Ali V. , Zulfequar M. , Mazharul Haq M. , Husain M.

Open Chemistry

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2006

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tom 4

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nr 4

565-577

EN

The temperature dependence of direct current (dc) conductivity was studied for various samples of polyaniline-polyvinylchloride (PANI-PVC) blended films. Polyaniline was doped with different concentrations of sulfamic acid in aqueous tetrahydrofuran (THF) and the blended films were prepared by varying the amount of doped PANI relative to a fixed amount of PVC. The dc conductivity of PANI-PVC blended films was measured to determine the effect of sulfamic acid (dopant) in the temperature range (300–400K). The mechanism of conduction is explained by a two-phase model. In order to evaluate the effect of the dopant, conductivity-derived parameters such as the pre-exponential factor (σ o) and the activation energy (ΔE) were calculated. The structural changes of polyaniline-PVC blended films were characterized by FTIR spectroscopy that explores information about the suitability of the dopant in the chemical doping process.

2

The influence of Fermi resonance and of isotopic substitution on the infrared spectra of hydrogen bonded crystals

100%

Ratajczak H. , Orville-Thomas W. J. , Yaremko A. , Ostrovskii D.

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1999

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tom Vol. 47, No. 3

193-208

EN

A theoretical approach, which takes into account both the Fermi resonance effect and strong anharmonic interaction between high-frequency v(XH) stretching vibra-tions and the lattice phonons, has been used to explain the IR spectral profiles of NaHF2 , HCrO2 and HCoO2 crystals and their deuterated analogues. Good correlation between the theoretical and experimental spectra has been obtained. It is shown that qualitative changes in the IR spectra of the crystals arising with isotopic substitution are mainly due to the change of the resonance conditions. It is found that in DCrO2 and DCoO2 crystals Fermi resonance is strong, whereas in HCrO2 and HCoO2 materials it is weak.

3

Inversion of Remote Sensing Data Using Multiple Ratios of Spectral Radiation Intensities and Neural Networks

100%

Cięszczyk S.

Acta Physica Polonica A

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2017

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tom 131

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nr 6

1454-1459

EN

The article presents a method for determining the content and temperature on the basis of spectra from remote measurements. The technique uses measurements of a high resolution radiation spectrum that allows the visibility of the individual rotational lines of gases such as CO₂, used here in the range of 2470-2495 cm¯¹. At the same time a new algorithm is applied of pre-processing the spectrum, involving the use of multiple ratios of intensity at several wavenumbers as input to an inverse model based on neural networks. Due to it, the dimensionality of the input can significantly be reduced. Additionally, the data interpreted do not have to be measured in units of spectral radiance. Thus only the calibration of the sensitivity of the spectrometer at various wavelengths is required. The neural models were constructed on the basis of data from the simulation. The proposed method works with a uniform layer of radiating gas for determining the temperature and CO₂ content. For a non-uniform layer it is possible to determine the line-of-sight temperature profile and average gas content. The method can be extended to different spectral ranges and to other gases present in substantial quantities in the exhaust gases of various processes.

4

Decomposition of Mg(HSeO3)2x3H2O and Mg(HSeO3)2, IR spectroscopic and thermoanalytical investigations

88%

Engelen B. , Muller H. , Unterderweide K.

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1998

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tom Vol. 72, nr 2

263-268

EN

By crystallization from aqueous Mg(HSeO3)2 solutions, single cristals of Mg(HSeO3)2x3H2O, Mg(HSeO3)2, and MgSe2O5 could be obtained. The compounds have been characterized by means of IR spectroscopy. The dehydration mechanisms of Mg(HSeO3)2x3H2O and Mg(HSeO3)2 have been studied using TG, DTA and high-temperaure Raman techniques. DTA and TG measurements indicate that the thermal decomposition of Mg(HSeO3)2x3H2O results in the direct formation of the diselenite MgSe2O5. High-temperature Raman experiments under quasi static conditions (heating rate<5K/h, isothermal intervals of -1h) show that Mg(HSeO3)2x3H2O decomposes in two steps under the intermediate formation of the anhydrous hydrogenselenite Mg(HSeO3)2.

5

Charge-sensitive vibrational modes in the (EDT-TTF-OX)2AsF6 chiral molecular conductors

88%

Olejniczak I. , Frąckowiak A. , Matysiak J. , Madalan A. , Pop F. , Avarvari N.

Open Physics

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2014

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tom 12

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nr 3

215-220

EN

Infrared and Raman spectra of three chiral molecular conductors (EDT-TTF-OX)2AsF6, comprising of two salts based on enantiopure EDT-TTF-OX donor molecules and one based on their racemic mixture, have been measured as a function of temperature. In the frequency range of the C=C stretching vibrations of EDT-TTF-OX, charge-sensitive modes are identified based on theoretical calculations for neutral and oxidized EDT-TTF-OX using density functional theory (DFT) methods. The positions of C=C stretching modes in both Raman and infrared spectra of the (EDT-TTF-OX)2AsF6 materials are analyzed assuming a linear relationship between the frequency and charge of the molecule. The charge density on the EDTTTF-OX donor molecule is estimated to be +0.5 in all investigated materials and does not change with temperature. Therefore we suggest, that M-I transition observed in (EDT-TTF-OX)2AsF6 chiral molecular conductors at low temperature is not related to the charge ordering mechanism.

6

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

88%

Celik O. , Tiras E. , Ardali S. , Lisesivdin S. , Ozbay E.

Open Physics

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2012

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tom 10

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nr 2

485-491

EN

The longitudinal optical (LO) phonon energy in AlGaN/GaN heterostructures is determined from temperature-dependent Hall effect measurements and also from Infrared (IR) spectroscopy and Raman spectroscopy. The Hall effect measurements on AlGaN/GaN heterostructures grown by MOCVD have been carried out as a function of temperature in the range 1.8-275 K at a fixed magnetic field. The IR and Raman spectroscopy measurements have been carried out at room temperature. The experimental data for the temperature dependence of the Hall mobility were compared with the calculated electron mobility. In the calculations of electron mobility, polar optical phonon scattering, ionized impurity scattering, background impurity scattering, interface roughness, piezoelectric scattering, acoustic phonon scattering and dislocation scattering were taken into account at all temperatures. The result is that at low temperatures interface roughness scattering is the dominant scattering mechanism and at high temperatures polar optical phonon scattering is dominant.

7

Theoretical simulation of infrared spectra of acetylsalicylic acid

75%

Boczar M. , Wójcik M. J. , Szczeponek K. , Jamróz D. , Zięba A.

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2002

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tom Vol. 50, No. 4

397-402

EN

Theoretical simulation of the v(s) stretching band is presented for acetylsalicylic acid (aspirin) at two temperatures 77 and 300 K. The simulation takes into account adiabatic couplings between the high-frequency O-H stretching and the low-frequency intermolecular O...O stretching modes, linear and quadratic distortions of the potential energy of the low-frequency vibrations in the excited state of the O-H stretching vibration, resonance interaction between the two hydrogen bonds in a dimer, and Fermi resonance between the O-H stretching and the overtone of the O-H bending vibrations.

8

Nucleophilic additions in Cu(II), Ni(II), Co(II) pseudohalide-4-halogenopyrazole systems

63%

Hvastijova M. , Kohout J. , Mroziński J. , Jager L.

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1999

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tom vol. 73 nr 2

271-278

EN

From M(II)-Y--4-X-pz systems, where M=Cu, Ni, Co; Y=NCO, C(CN)3, N(CN)2; X=Cl, Br, I (pz = pyrazole), new compounds of the type [MY2(4-X-pz)2] and [M(4-X-pz×Y)2] have been prepared. Compounds [M(4-X-pz×Y)2] arise by nucleophylic addition of imine nitrogen from 4-X-pz to cyano carbon of the pseudohalide under formation of five-membered metallocycle. The influence of X substituent on the course of this reaction with various M(II) and Y was investigated. An uncomplete course of nucleophilic addition is revealed by formation of mixed products, consisting of [MY2(4-X-pz)2] and [M(4-X-pz×Y)2]. All compounds were studied by infrared and electronic spectroscopy and probable structures were assigned to the relevant species.

9

Anharmonic effects on the OH stretching vibrations of the Na5H3(SeO4)4x2H2O crystal

63%

Ratajczak H. , Barnes A. J. , Baran J. , Marchewka M. K. , Yaremko A. M.

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2001

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tom Vol. 49, No. 1

1-8

EN

Polarized infrared spectra of pentasodium trihydrogen tetraselenate dihy-drate, Na(5)H(3)(SeO4)(4)2H(2)O, are analysed using a model which takes account of the Fermi resonance interactions between the OH stretching vibrations and various combination tones. It is demonstrated that the short, centrosymmetric, hydrogen bond of the hydro-gendisefenate anion generates an intense broad absorption whose spectral features can be described taking into consideration strong interaction between the va (OHO) stretching vibration and lattice phonons, while the longer hydrogen bond linking hydrogenselenate ions to the hydrogendiselenate anion gives a typical ABC band structure.

10

Molecular orbital study of hydrated clusters of LiOH

51%

Miyazaki S. , Osamura Y.

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2002

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tom Vol. 50, No. 4

463-489

EN

The molecular structures of the hydrated species of LiOH, LiOH(H2O)n for n = 1 ~ 5, were studied in terms of density functional B3LYP molecular orbital method. Since the water molecules act as both acid and base toward LiOH, all stable structures located at energy minima are found to be cyclic geometries. The distance between Li+ and OH(-) increases as the number of water molecules increase. Due to the covalent nature of LiOH, the dissociation of LiOH toward Li and OH(-) requires sufficient number of water molecules. Only non-dissociated structures were obtained in the case of a small number of water molecules (n < 3). Even in the case of LiOH(H(2)O)(5), the non-dissociated structures are calculated to be more stable than the dissociated structures. The number of isomers increases substantially with the increase of the number of water molecules. The ionic structures can be classified into contact ion-pair and solvent separated ion-pair structures. The four water molecules can coordinate to Li+ ion and the OH(-) ion can accept three water molecules in most cases. The stabilization energies of hydration for LiOH are calculated to be much larger than those of strong acids such as HCl and H(2)SO(4). The predicted vibrational spectra of each size of clusters indicate an irregular tendency of the stretching frequency of Li-O depending on the number of water molecules.

11

Rare earth oxide films: their preparation and characterization

44%

Wiktorczyk T.

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tom Vol. 31, nr 1

5-33

EN

Summarises the results of our investigations dealing with preparation of rare earth oxide films and examinations of their physical properties. Different deposition methods have been applied for fabrication of these films and rare-earth-oxide-based thin film coatings. The main results concerning film microstructure and optical properties in the wavelength range from the UV up to the IR are presented. Electrical and dielectric studies have been carried out in the time domain and in the frequency domain (from very low frequencies up to radio frequencies) for selected rare earth oxides. MIM sandwich-type structures have been fabricated for this aim. Trapping levels in these oxides have been investigated. The complex impedance diagnostics was applied to the analysis of the volume of the R/sub 2/O/sub 3/ film and interfacial properties (metal/insulator barriers) of M/R/sub 2/O/sub 3//M thin film structures.