Liquid surface diffractometer

The molecules investigated on a liquid surface diffractometer are usually insoluble and amphiphilic [48], having a hydrophobic moiety (typically a hydrocarbon chain with at least 13 carbons), traditionally denoted the tail, and a hydrophilic head that can be neutral or charged depending on pW or on the concentration of other ions in the subphase. More complex molecules can also be studied, e.g., proteins, which can form a monomolecular layer by adsorption to the air-water interface. Interactions or chemical reactions can be studied in situ by injecting macromolecules or a catalyst under a given surface layer initially assembled at the air/liquid interface. 

Catalyst surface areas were measured using the multi-point BET method on a Carlo-Erba Ins. Sorpty 1750. Before the measurements, the samples were heated under dynamic vacuum at 573 K for 1 h in order to remove adsorbed water and impurities. Measurements were made at liquid nitrogen temperature with nitrogen as the adsorbate gas. Powder X-ray diffraction measurements were performed on a Siemens Model D-500 diffractometer with Co Kc monochromatic radiation (X = 1.78901 A) and the high resolution electron microscopy was carried out on a Topcon EM-002B microscope. To prevent artefacts no solvents were used in the preparation and mounting of samples for HRTEM. 

The X-ray diffraction (XRD) patterns were collected on a RIGAKU diffractometer, operated at 30kV and 20 mA and using CuK radiation (A,=0.15405nm). The specific surface areas of the catalysts were tested on a home-made analyzer, following the BET method from air isotherms determined at liquid nitrogen temperature. The structure properties of the catalysts were characterized by IR spectroscopy using a PE-783 IR spectrometer. The amount of samples were mixed with KBr in form of disks, and the spectra were taken at room temperature. 

Toby BH, Egami T (1992) Accuracy of Pair Distribution Function-Analysis Applied to Crystalline and Noncrystalline Materials. Acta Crystallogr A48 336-346 Tomilin MG (1997) Interaction of liquid crystals with a solid surface. J Opt Technol 64 452-475 Toraya H, Hibino H, Ohsumi K (1996) A New Powder Diffractometer for Synchrotron Radiation with a Multiple-Detector System. J Synchrot Radiat 3 75-83... 

The magnetic field is maintained for 2 h, and the sample is cooled rapidly on a cold metal surface or with liquid nitrogen as soon as the power supply of the magnet is turned off. The film is then placed in the sample holder of a suitable X-ray diffractometer (with axis vertically aligned) and the diffraction pattern is recorded with a flat-plate camera. 

XRD patterns were recorded on a Phillips PW 1051 diffractometer using Cu Ka radiation. SEM photographs were obtained on a Hitachi microscope. BET surface areas of the catalysts were determined using nitrogen adsorption at liquid nitrogen temperature in a... 

The BET surface area was measured by nitrogen adsorption at liquid nitrogen temperature. Prior to BET measurements, samples were outgassed at 350 C for 2 hr. XRD patterns were obtained on Rigaku diffractometer using CuKa radiation. 

N2 adsorption/desorption isotherms for BET surface area and pore size distribution measurements were collected at liquid nitrogen temperature using a Micromeretics ASAP 2010 apparatus. Before the measurement, approx. 50 mg of the sample was dehydrated under vacuum at 573 K overnight. Pore diameters were calculated using the BJH method on the adsorption branch of the isotherm. X-ray diffraction (XRD) powder patterns were recorded between 1 and 10° (or 3 and 80°) (20) on a Bruker (Siemens) D 5005 diffractometer using CuKa2 radiation with steps of 0.02° and 10 s (or 1 s) per step. 

Powder X-ray diffraction patterns were collected on a Sbimadzu XD-3A diffractometer operated with Cu Ka radiation (X=1.541sA). Infrared spectra were recorded on a Nicolet 510P FT-IR instrument using KBr wafer techniques. The surface area and pore size distribution of the sample were measured on a Micromeritics ASAP 2000 instrument. The sample was first degassed at SSO C, and followed by the measurement of Nj adsorption-desorption isotherm at liquid nitrogen temperature. 

---