|
| << vorige | volgende >> |
Tijdschrift beschrijving
Alle jaargangen van het bijbehorende tijdschrift
Alle afleveringen van het bijbehorende jaargang
Alle artikelen van de bijbehorende aflevering
Details van artikel 5 van 18 gevonden artikelen
| Titel: |
Degree of order of aromatic and N-heterocyclic probes embedded in sodium lauril sulphate lyomesophases |
| Auteur: |
Fo, Ourides Santin Politi, Mario Jose Vanin, Jose Atilio Isolani, Paulo Celso |
| Verschenen in: |
Liquid crystals |
| Paginering: | Jaargang 11 (1992) nr. 1 pagina's 15-23 |
| Jaar: |
1992-01-01 |
| Inhoud: |
Linear dichroism, time-resolved and steady-state anisotropy emission fluorescence were applied to the study of chromophores embedded in aligned and nonaligned lyotropic nematic phases. The phases are composed of sodium dodecyl sulphate, 1-decanol and water and contain long rod-like aggregates, which align their long axis parallel to an applied magnetic field. Pyrene, p-terphenyl, 9, 10-diazaphenanthrene and carbazole were dissolved in these aggregates. The dichroic ratio results obtained for these probes in aligned mesophase show two main trends: firstly the hydrocarbons (pyrene and p-terphenyl) exhibit a dichroic ratio (ratio between absorption intensities of two perpendicular polarized beams of light) higher than unity for their in-plane long axis polarized band and a dichroic ratio near unity for their in-plane short axis polarized band. In this case the plane of the molecule tends to be oriented perpendicular to the symmetry axis (C∞ axis) of the aggregates; and secondly for the N-heterocyclic molecules (9, 10-diazaphenanthrene and carbazole) the situation is reversed, and these two probes tend to align the molecular plane nearly parallel to the symmetry axis of the aggregates. The steady-state and time-resolved anisotropy values obtained for pyrene are typically 0.060 and 0.080 for non-aligned and aligned lyomesophases, respectively. In the first case the anisotropy is caused by a photoselective excitation of pyrene molecules embedded in a viscous environment and in the second, besides the photoselection, there is the effect of alignment by the applied magnetic field. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 5 van 18 gevonden artikelen
| << vorige | volgende >> |