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1
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Optimization of Azimuthal Scan Procedure for Absolute Structure Determination

100%
Grochowski J., Serda P.
Acta Physica Polonica A
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1997
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vol. 91
|
issue 5
961-968
EN
The paper describes the application of the azimuthal scan technique for absolute structure determination using X-ray anomalous dispersion. A diffraction pattern with rotation around the scattering vector provides information about various anisotropic effects: absorption, extinction and multi-beam interaction. Recording of azimuthal scans for Friedel pairs is proposed as an alternative to single reflection measurement. Several factors affecting the smoothness of the azimuthal scan curves are discussed and a procedure for eliminating various sources of errors, involving a Fourier filtering, is proposed in order to increase feasibility of chiral discrimination.
2
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Absolute Structure Determination in Absence of Heavy Scatterers

80%
Grochowski J.
Acta Physica Polonica A
|
1997
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vol. 91
|
issue 4
745-756
EN
Methods of absolute structure determination for molecules containing only light atoms (C, H, N, O) are discussed in the paper. This experimentally difficult problem has a direct application in the structure determination of naturally originated compounds and modern chiral drugs. Several experimental methods of absolute structure determination like electron diffraction, multiple X-ray diffraction and X-ray anomalous scattering techniques are briefly discussed and compared. An application of dedicated azimuthal scan method for the case of hexamethylenetetramine is given as an illustration of this technique.
3
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The Influence of the Spin Crossover on the Crystal Structure of the [Fe₃(hyetrz)₆(H₂O)₆](CF₃SO₃)₆ Complex Compound

80%
Książek M., Bednarek G., Kusz J.
Acta Physica Polonica A
|
2016
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vol. 130
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issue 4
873-875
EN
[Fe₃(hyetrz)₆(H₂O)₆](CF₃SO₃)₆ (where hyetrz = 4-(2'-hydroxyethyl)-1,2,4-triazole) is an interesting linear, trinuclear iron(II) compound with incomplete spin crossover. We reinvestigated crystal structure of this compound in the wide temperature range because the knowledge only about the crystal structure in the initial and final phases is not sufficient to establish correlations between the structural and magnetic properties of the spin crossover system. The complex [Zn₃(hyetrz)₆(H₂O)₆](CF₃SO₃)₆ was used for comparison because it does not exhibit spin crossover phenomenon and it is isostructural with a high spin phase of Fe(II).
4
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Dynamics and Phase Transitions of 4-Bromobenzylidene-4'-pentyloxyaniline and 4-Bromobenzylidene-4'-hexyloxyaniline as Studied by Dielectric Spectroscopy

80%
Osiecka N., Massalska-Arodź M., Galewski Z., Chłędowska K., Wróbel S., Morito T., Yamamura Y., Saito K.
Acta Physica Polonica A
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2013
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vol. 124
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issue 6
913-916
EN
Significant differences in phase sequence and dynamics between 4-bromobenzylidene-4'-pentyloxyaniline (5BBA) and -bromobenzylidene-4'-heksyloxyaniline (6BBA) substances were detected by broadband dielectric spectroscopy. In the smectic A (6BBA), the smectic B (found in both substances) and the smectic E (5BBA) phases the relaxation was ascribed to reorientations of the molecules around the short axes. Slow dynamics detected in the smectic E and in two crystalline phases of 5BBA was ascribed to conformational changes of molecular chains. Coexistence of Cr(I) and Cr(II) conformationally disordered crystal (CONDIS) phases was observed and vitrification of Cr(II) was identified with help of polarizing microscopy.
5
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Spectral Investigations of Fullerene-Porphyrin Complexes

51%
Barszcz B., Bogucki A., Laskowska B., Ion R., Graja A.
Acta Physica Polonica A
|
2007
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vol. 112
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issue S
S-143-S-152
EN
Spectral investigations of someμ-oxo-dimer complexes of trivalent metals (Mn, Fe) with two different ligands: tetraphenylporphyrin and tetranaphthylporphyrin (TNP), and fullerene (C_{60} and C_{70}) complexes withμ-oxobis[5,10,15,20-tetraarylporphyrinatometal (III)] (TXP-M)_2O dimer, where M = Fe, Mn and X = phenyl or naphthyl, are presented. Discussion of the main electronic and vibrational bands observed in the UV-Vis-IR and Raman spectra of both classes of fullerene-porphyrin systems is given. Experimental data are completed with the quantum chemical calculations of MnTNP^+ component.
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