Autor: Legrand, Ch. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Dynamics of Nematogenic Molecules with Transverse Component of Dipole Moment
Autorzy:: Douali, R.
Czechowski, G.
Legrand, Ch.
Jadżyn, J.
Tematy:: 64.70.Md
77.84.Nh
77.22.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037273.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the results of studies of the dielectric relaxation of nematic 4'-butyloxy-3-fluoro- 4-isothiocyanatotolane, performed for different values of the angle between the probing electric field E and the macroscopic orientation of the sample (the director n) forced by the magnetic field B. Due to a relatively large transverse component of the dipole moment of 4'-butyloxy- 3-fluoro-4-isothiocyanatotolane, the studies allowed one to interpret consistently the dielectric relaxation spectra connected with the molecular rotation around the long axis.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Anomalous Dielectric Spectra of Ferro- and Ferrielectric Liquid Crystalline Phase in MHPNBC
Autorzy:: Dubois, F.
Douali, R.
Wawrzyniak, A.
Legrand, Ch.
Ropa, P.
Wróbel, S.
Dąbrowski, R.
Tematy:: 77.22.Gm
77.84.Nh
64.70.M; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399013.pdf Link otwiera się w nowym oknie
Opis:: MHPOBC analogue with long achiral alkyl chain has been investigated by dielectric spectroscopy studies in the wide temperature range. Low frequency dielectric spectroscopy revealed the existence of normal ferroelectric phase (in a narrow gap), two ferri- and three antiferroelectric phases in addition to paraelectric phase and alpha sub-phase. The compound studied shows exceptionally strong dependence of the dielectric permittivities on measuring electric field in the temperature range of ferro- and ferrielectric phases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Dielectric and Electrooptic Investigations of B Phases οf Banana-Shaped Thioesters
Autorzy:: Wierzejska-Adamowicz, M.
Ossowska-Chruściel, D.
Chruściel, J.
Douali, R.
Legrand, Ch.
Marzec, M.
Mikułko, A.
Sikorska, A.
Wróbel, S.
Tematy:: 77.84.Nh
77.84.-s
78.20.Jq; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1538244.pdf Link otwiera się w nowym oknie
Opis:: Electrooptic and dielectric measurements were done for B phases of two banana-shaped homologues 1,3-phenylene bis{4-[(4-nonylo-xy-benzoyl)sulfanyl]benzoate (9OSOR) and 1,3-phenylene bis{4-[(4-dodecylo-xy-benzoyl)sulfanyl]benzoate (12OSOR). Polarizing microscopy allowed to identify $B_{1}$ phase for 9OSOR and $B_{2}$ phase for 12OSOR on the basis of texture observation. Spontaneous polarization measurements were performed using reversal current method. The current response to applied triangular voltage shows that $B_{1}$ phase is a ferroelectric and $B_{2}$ phase - antiferroelectric one for which two well separated peaks were observed. Polarization for phase $B_{1}$ of 9OSOR is rather small and its temperature dependence is unusual for ferroelectric liquid crystals - it increases with temperature. Spontaneous polarization for $B_{2}$ phase of 12OSOR compound is of about 600 nC/$cm^{2}$. Dielectric spectra measured with bias field for $B_{2}$ phase of 12OSOR show two well separated relaxation processes. In the low frequency range the relaxation process is connected with fluctuations of ferroelectric domains. The relaxation process in the high frequency range appearing also without bias field is connected with molecular reorientation. The dielectric spectra measured for $B_{1}$ phase of 9OSOR with and without bias voltage showed only one dielectric relaxation process connected with molecular reorientation around the short axis.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Polymorphism of Chiral Thioester Studied by Dielectric Spectroscopy
Autorzy:: Wawrzyniak, A.
Chruściel, J.
Douali, R.
Dubois, F.
Leblond, J.
Legrand, Ch.
Ossowska-Chruściel, D.
Marzec, M.
Ropa, P.
Czerwiec, J.
Wróbel, S.
Tematy:: 77.84.Nh
64.70.M-
77.22.Gm
77.22.Ej; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399012.pdf Link otwiera się w nowym oknie
Opis:: (S)-(+)-4'-[(4-(1-methylheptyloxycarbonylphenyl) thiocarbonylphenyl]-decyloxybenzoate (in short 10.OPOSMH) was studied by complementary methods. The substance shows rich polymorphism. In addition to ferroelectric and antiferroelectric smectic C* phases it possesses three ferrielectric sub-phases. Phase transitions between the phases were revealed by differential scanning calorimetry and static dielectric permittivity measurements. The aim of this paper was to study phase transitions and differences in dielectric spectra shown by different phases. Collective and molecular dynamics of all phases shown by 10.OPOSMH will be discussed in terms of theoretical models. Dielectric spectra of antiferroelectric phase show two characteristic dielectric relaxation modes: one connected with the molecular process (reorientation around the short axis) and the other originating from fluctuations of antiferroelectric order parameters.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Polymorphism of chiral thioester studied by dielectric spectroscopy
Autorzy:: Dubois, F.
Legrand, Ch.
Chruściel, J.
Ossowska-Chruściel, D. M.
Douali, R.
Czerwiec, Jan
Wróbel, Stanisław
Leblond, J.-M.
Marzec, Monika
Wawrzyniak, Adriana
Ropa, P.
Opis:: (S)-(+)-4'-[(4-(1-methylheptyloxycarbonylphenyl) thiocarbonylphenyl]-decyloxybenzoate (in short 10.OPOSMH) was studied by complementary methods. The substance shows rich polymorphism. In addition to ferroelectric and antiferroelectric smectic C^{*} phases it possesses three ferrielectric sub-phases. Phase transitions between the phases were revealed by differential scanning calorimetry and static dielectric permittivity measurements. The aim of this paper was to study phase transitions and differences in dielectric spectra shown by different phases. Collective and molecular dynamics of all phases shown by 10.OPOSMH will be discussed in terms of theoretical models. Dielectric spectra of antiferroelectric phase show two characteristic dielectric relaxation modes: one connected with the molecular process (reorientation around the short axis) and the other originating from fluctuations of antiferroelectric order parameters.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 6.

Tytuł:: Direct Observation of Localized Modes in an Open Disordered Microwave Cavity
Autorzy:: Mortessagne, F.
Laurent, D.
Legrand, O.
Sebbah, P.
Vanneste, Ch.
Tematy:: 42.25.Dd
72.15.Rn; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2047826.pdf Link otwiera się w nowym oknie
Opis:: We present measurements of the spatial intensity distribution of localized modes in a two-dimensional open microwave cavity randomly filled with cylindrical dielectric scatterers. The robustness of these modes with respect to a modification of the boundaries of the scattering region is successfully established. From a comparison with numerically calculated modes, we can extract precise values of the localization length which are in agreement with the measured spectral widths. These results constitute unambiguous signatures of the existence of strongly localized electromagnetic modes in two-dimensional open random media.
Dostawca treści:: Biblioteka Nauki

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