Multilayers of an Fe(II)-polyelectrolyte-amphiphile complex (Fe-PAC) were investigated simultaneously by energy-dispersive X-ray reflectivity and in-plane diffraction at the bending-magnet beamline at BESSY II. By recording spectra between room temperature and about 348 K with a time resolution of about 60 s, two phase transitions were identified and the respective activation energies were determined. Owing to a fixed geometrical set-up, an energy-dispersive experiment is suitable for measuring X-ray reflectivity and in-plane X-ray diffraction of thin organic films simultaneously. Installed at a bending magnet at BESSY II and using an energy range of 4 < E < 25 keV, both reflectivity and diffraction spectra can be collected within about 60 s. The performance is demonstrated by temperature- and time-resolved measurements of the phase transition behaviour of multilayers of an Fe-PAC deposited on a silicon support by means of the Langmuir-Blodgett (LB) technique. By measuring the X-ray reflectivity while increasing the temperature, it is shown that the original LB phase is not stable and transforms irreversibly into a liquid-crystalline (LC)-like phase at about 318 K. At the same temperature the in-plane diffraction signal vanishes reversibly, reflecting rotational disorder of the hexagonal arrangement of amphiphilic chains. Its activation energy is determined to be about 1.3 eV. At about 338 K a second irreversible phase transition occurs to another LC phase with smaller vertical layer spacing. This transition is reversible between 329 K and 338 K.

The insertion and systematical displacement of two vicinal hydroxyl groups along the hydrophobic alkyl chain of methyl octadecanoates generates bipolar amphiphiles. These molecules offer the possibility to investigate the influence of the position and the stereochemistry of the hydroxyl groups on monolayer properties and intermolecular interactions. Monolayers of enantioenriched and racemic vicinally dihydroxylated methyl octadecanoates (DHOs) were investigated using fluorescence microscopy, fluorescence spectroscopy, and grazing incidence X-ray diffraction (GIXD). The monolayers of racemic threo-2,3-DHO, erythro-9,10-DHO, and 17,18-DHO show heterochiral discrimination in fluorescence microscopy investigations due to a preferential interaction between the enantiomers with the opposite configuration. GIXD measurements exhibit rectangular unit cells for the racemic films, while the enantiomers form oblique and therefore chiral structures. Erythro-9,10-DHO exhibits an extraordinarily large lattice spacing due to the disturbing effect of the hydroxyl groups. The formation of rectangular lattices by racemic films strongly suggests that chiral phases such as in the case of the enantiomers are prevented by the dimerization due to stereospecific hydrogen bonds between the two antipodal enantiomers. Accordingly, the individual enantioenriched amphiphiles are able to distinguish between the same and antipodal enantiomers, and thus they are able to recognize chemical structures at a molecular level. Fluorescence spectroscopy at the air−water interface revealed whether the hydroxyl groups or the methyl ester of the α,ω-bipolar amphiphile 17,18-DHO is directed to the water surface in the condensed state at subphase temperatures of 278 and 293 K, respectively.

Background This paper presents a gedankenexperiment or “thought experiment” on the solar neutrino beam in regard to a diffraction study of the Earth's core. Materials and Methods The Sun is the source of the most intense neutrino radiation on Earth. Owing to the Sun's long distance from the Earth it forms a parallel beam of white radiation as well as discrete lines. The coherent scattering of these neutrinos at the Earth's solid core produces a diffraction pattern on the Earth's night side. Results I will show that this diffraction pattern will be most likely observable on the Earth's surface by using a detector configuration that is located between the tropics. There has not been any neutrino detector that is located on the Earth's surface and suitable for these measurements. Conclusion An investigation of the diffraction pattern of the solar neutrino beam would provide a tool for studying not only the Earth's center but also the neutrinos themselves.