Amphiphilic carbohydrate-based mesogens incorporating structural features of calamitic liquid crystals

Several examples of liquid-crystalline carbohydrate derivatives incorporating a carbocyclic ring in the side chain are reported and the influence of structural variations discussed. The mesophase observed for all compounds described is smectic A and the mesophase stability is strongly affected by the linking unit between the carbocyclic and carbohydrate moieties.     

Zur Thermolumineszenz von NaCl/Ag

Angular and energy dependence of the polarizationP of slow electrons scattered elastically by a mercury-atom beam have been measured. The angular resolution being comparatively high (about ±1°), the results could be compared directly with uncorrected theoretical values and high polarizations (up to ¦P¦=0.85±0.05) could be observed. The polarization was measured by a Mott-detector, the electrons scattered by the mercury atoms having been accelerated to 120 keV. The high yield of this detector made up for the rather low intensity of the observed beam caused by the high angular resolution and resulted in low statistical errors. The experimental results, which cover the angular range from 30° to 150° and energies from 180eV to 1700eV are in good agreement with the theoretical values ofHolzwarth andMeister as well as with those ofBunyan andSchonfelder.     

Flashlamp-pumped high gain laser dye amplifiers

Flashlamp-pumped organic dyes (e.g. Rhodamine 6G) are considered as an amplifying medium. Calculations have been made for optimising the small signal gain and the concentration of the active molecules for given dye cell dimensions. Under the assumption of weak pumping the maximum useful gain is only dependent on the geometrical dimensions of the cell. An optimum concentration could be derived resulting from the compromise of uniform gain distribution over the cylindrical cross section of the medium and maximum absorption of pump power. It is shown that the near uv-radiation of the flashlamp is very efficient in achieving the desired inversion. Some experiments supporting the theoretical results are given.