Rotating solid sample cell

Solid sample cup Rotating solid sample cup Liquid cup Viscous liquid cup Transmission liquid cell Disposable sample cup Transflectance cell Research transflectance cell Chemical cell... 

Figure 3 shows one of our photoacoustic cell for X-ray spectroscopy of solid samples The cylindrical cell has a sample chamber at the center with volume of 0.16 cm which has two windows of beryllium (18 mm x 0.5 mm thickness). A microphone cartridge is commercially available electret type (10 mm ) and the electronics of preamplifier for this microphone is detailed elsewhere Figure 4 shows the typical experimental setup for spectroscopic study X-ray was monochromated by channel cut silicon double crystal (111) and ion chamber was set to monitor the beam intensity. Photoacoustic signal intensity was always divided by the ion chamber current for the normalization against the photon flux. X-ray was modulated by a rotating lead plate (1 mm thick) chopper with two blades. 

CD samples must be isotropic, at least in the direction perpendicular to the light path, since linear dichroism (LD, birefringence) causes large distortion of CD spectra. Therefore, samples of solid dispersions, membranes, films, gels, and liquid crystals should be prepared with great care to minimize anisotropy. Furthermore, the measurement of nonsolution samples should be repeated several times after successive rotation of the cell around the light beam axis to check the independency from linear dichroic interference. Some reliable studies show LD data with CD curve in order to examine artifacts. The linear dichroic interference may be too large for solid-state samples, and hence their measurement may require specialized instruments. Chiral liquid crystal (nematic or smectic C phase) exhibits a characteristic circular dichroic phenomenon irrelevant to... 

Commercial D,L-methionine contains two crystalline forms, which could be separated by ciystallization from water or water-ethanol. The C spectrum of solid u,L-methionine showed two chemical shifts for the methyl carbons (18.7 and 15.8 ppm) the conformational difference is also reflected in the carbon resonances of C-P and C-y [14]. The selenoproteins nowadays attracte much attention, and selenomethionine is the predominant form of selenium in food. Se and C CP MAS experiments were employed to study the structure and dynamics of D,L-and L-selenomethionine [15]. The c CP MAS spectrum of solid D,L-selenomethionine showed one signal at 111.5 ppm (see Figure 12-1) in the case of L-selenomethionine two resonances at 122.9 and 84.5 ppm indicated the presence of two molecules in the unit cell. L-selenomethionine undergoes a phase transition at 305 K and isomerization when the sample is rotated rapidly (at a spinning rate of 14.5 kHz). 

Optical rotation of the purified compound was measured in ethanol on Parkin-Elmer 241 or Union Giken PM-101 polarimeters using 1 dm cell. The other spectroscopic measurements were carried out by a JEOL-PMX 60 for NMR and Hitachi IR-285 spectrometers for IR spectra of the solid (KBr disk). The X-ray diffraction patterns of the powdered samples were taken in the region of 5 to 35° by a Rigakudenki Model DC-8 X-ray diffractometer using Ni-filtered Cu-Kq radiation. The thermal behavior of the specimens was observed with a Rigakudenki TG-DSC analyzer, which has been previously calibrated with a standard substances. 

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