CuKa radiation

Conversion to cellulose II and cellulose III via caustic mercerization and Hquid ammonia treatment are commercial textile processes that are discussed later. Figure 7 shows the characteristic diffractograms (CuKa radiation) of native cellulose, cellulose mercerized with sodium hydroxide, and cellulose treated with Hquid ammonia. 

X - Ray powder diffraction data of some important tantalum and niobium fluoride compounds (CuKa radiation)... 

Figure 2. XRD pattern of an EMD sample (Chemetals). The diffractogram is taken with a Bruker AXS D5005 diffractometer using CuKa radiation and a scintillation counter. The step width is 0.02° with a constant counting time of 10 s / step.

It has been mentioned above that bir-nessite-type samples can show a wide variety of different XRD patterns. Mostly, the samples show only XRD peaks around 240 pm (20 37° for CuKa radiation) and 142 pm (2 ss 66°). These peaks correspond to the (1 0 0) and (110) reflections of the simple hexagonal setting of the S - Mn02 unit cell. Additionally, in some natural as well in synthetic materials the basal plane (0 0 l) reflections (001) and (0 0 2) do occur at about 700 pm (26 312°) and 350 pm (26 25°), respectively. 

X-Ray diffraction from single crystals is the most direct and powerful experimental tool available to determine molecular structures and intermolecular interactions at atomic resolution. Monochromatic CuKa radiation of wavelength (X) 1.5418 A is commonly used to collect the X-ray intensities diffracted by the electrons in the crystal. The structure amplitudes, whose squares are the intensities of the reflections, coupled with their appropriate phases, are the basic ingredients to locate atomic positions. Because phases cannot be experimentally recorded, the phase problem has to be resolved by one of the well-known techniques the heavy-atom method, the direct method, anomalous dispersion, and isomorphous replacement.1 Once approximate phases of some strong reflections are obtained, the electron-density maps computed by Fourier summation, which requires both amplitudes and phases, lead to a partial solution of the crystal structure. Phases based on this initial structure can be used to include previously omitted reflections so that in a couple of trials, the entire structure is traced at a high resolution. Difference Fourier maps at this stage are helpful to locate ions and solvent molecules. Subsequent refinement of the crystal structure by well-known least-squares methods ensures reliable atomic coordinates and thermal parameters. 

X-ray diffraction (XRD) measurements were carried out using a Dlano XRD-6 powderdiffractometer with CuKa radiation. 

X-ray Diffraction. Eliffiactograms were obtained with a ShiimdzuXD-Dl instrament with monochromator using CuKa, radiation. It was operated in continuous scan mode at 0.5° (20) min. ... 

X-ray diffraction was done using a Siemens D-500 diffractometer utilizing CuKa radiation (1.406 A). The data were collected as step scans, with a step size of 0.05° 29 and a count time of 2 s/step between 10° and 80° 29. 

Powder X-ray diffraction patterns were measured on PANalytical X Pert PRO high-resolution diffractometer with Alphal configuration using CuKa radiation (1.5406 A) in the range from 5° to 35° 20 with the 0.017° step per 100 s using fully opened X Celeration detector. For the XRD measurements Ti-Beta precursor gels were dried at ambient temperature and than grinded to powder. 

XRD patterns were recorded on a Bruker D5005 diffractometer using a monochromated CuKa radiation (20 = 0.5-10 °). Nitrogen physisorption measurements at -196 °C were... 

MCM-41 samples have been characterized by means of powder X-ray diffraction (X Pert Philips, CuKa radiation), nitrogen adsorption measurements at 77 K (Quantachrome Autosorbl) and Field Emission Scanning Electron Microscopy (Assing FESEM Supra 25) before soaking in SBF and after different immersion times. 

XRD analyses were performed on oriented samples prepared by spreading of the sample suspension on a glass slide, followed by drying at room temperature. The XRD patterns were obtained with a PW 1130/00/60 Philips diffractometer using CuKa radiation (/, = 1,5405 A). Chemical analysis was carried out on a Perkin Elmer 3100 atomic absorption spectrometer after dissolution of the sample with several acids (HF, HCIO4, HC1) for 24h, and HN03 in a second time. 

Fig. 27 X-ray diffraction pattern of our Ti02 fiber. The Ti02 fiber was pulverized, and the X-ray diffraction pattern of the powder was recorded with a Rigaku X-ray diffractometer with CuKa radiation with a nickel filter...

X-ray structural analysis of bromocriptine, crystallized as the base from dichloromethane/diethylether, has been carried out on a CAD 4-diffractometer with CuKa-radiation (16). 3371 reflexions were within sin G/A<0.62 A. Assessment of the structure was achieved by computation to a refinement of R = 0.033 for the absolute configuration. 

The three dimensional structure was obtained by means of single crystal X-ray diffraction. CuKa radiation, a graphite monochromator, and a photomultiplier tube were used to collect 1825 total reflections on an automated diffractometer. Of these, 1162 were used for the analysis. Figure 2 shows a computer generated drawing of halcinonide. The position of the chlorine atom was not clear from the Patterson map, but the direct method program "MULTAN" gave its position. 

Figure 7 is the powder X-ray diffraction pattern of halcinonide as obtained on a Philips powder diffraction unit emitting CuKa radiation at 1.54A. Using a scintillation counter detector, the sample was scanned and recorded from approximately 2 to 40 degrees (20). The table below is the sorted data.20... 

Powder X-ray diffraction (XRD) data were collected via a Siemens D5005 diffractometer with CuKa radiation (A. = 1.5418 A). Routine transmission electron microscopy (TEM) and Z-contrast microscopy were carried out using an HITACH HD-2000 scanning transmission electron microscope (STEM) operated at 200 kV. Nitrogen gas adsorption measurements (Micromeritics Gemini) were used to determine the surface area and porosity of the catalyst supports. Inductively coupled plasma (ICP) analysis was performed via an IRIS Intrepid II XSP spectrometer (Thermo Electron Corporation). 

Figure 1. An x-ray diffraction pattern from an oriented, noncrystalline fiber of the Rhizobium trifolii capsular polysaccharide using CuKa radiation. (Reproduced with permission from Ref. 16. Copyright 1987 Gordon and Breach.)...

X-ray diffraction powder patterns were recorded on a CGR Theta 60 instrument, using monochromated CuKa radiation. The adsorption capacities for several adsorbates were measured at room temperature by gravimetry, using a Cahn RH microbalance as proposed by Vaughan and Lussier (3 ). The samples were first treated in air for 5 hours at 480°C. The experiment was performed by passing, over the sample, a stream of nitrogen saturated by the vapor pressure of the sorbate at room temperature, the relative pressure P/Po was then equal to 1. 

The pH values of quenched autoclave contents are recorded prior to dilution with water for product recovery. Thermogravimetric analyses (T6A) were performed in air on a DuPont 951 thermogravimetric analyzer. A Siemens 12 X-ray diffractometer was used to collect X-ray powder diffraction data with CuKa radiation. Magic angle spinning P NMR spectra were recorded on a Bruker MSL 300 spectrometer. The P NMR spectra were taken at a frequency of 121.496 MHz and a spinning rate of 3-5 kHz. Chemical shifts are reported relative to 85 wt% H3PO4. 

Chemical composition of fresh HTs was determined in a Perkin Elmer Mod. OPTIMA 3200 Dual Vision by inductively coupled plasma atomic emission spectrometry (ICP-AES). The crystalline structure of the solids was studied by X-ray diffraction (XRD) using a Siemens D-500 diffractometer equipped with a CuKa radiation source. The average crystal sizes were calculated from the (003) and (110) reflections employing the Debye-Scherrer equation. Textural properties of calcined HTs (at 500°C/4h) were analyzed by N2 adsorption-desorption isotherms on an AUTOSORB-I, prior to analysis the samples were outgassed in vacuum (10 Torr) at 300°C for 5 h. The specific surface areas were calculated by using the Brunauer-... 

Figure 5 X-ray diffraction patterns using CuKa radiation of a xerogel dried at room temperature, fired at 600°C and annealed at 950°C. The peak observed at 600°C correspond to CuO, Y2Os and BaCOa. (After Reference 35.)...

X-Ray Powder Patterns. Samples for x-ray pattern determinations were sealed in 0.2-mm. glass capillary tubes under an atmosphere of argon. The samples were then exposed to nickel-filtered, CuKa radiation in an 11.459-cm. Debye-Scherrer camera for 18 to 20 hours. 

X-Ray Diffraction Analysis. X-ray powder diffraction data for indexing were obtained with a General Electric XRD-6 diffractometer. Samples were sealed in glass capillaries (0.5 mm o.d.) and exposed to nickel-filtered CuKa radiation. KCl or iridium was used as an internal standard. X-ray powder diffraction intensity data were obtained with a General Electric XRD-5 unit. Here,... 

Normally, if the assumed model for a crystal structure has an R value of 0.5 and resists attempts to refine to a lower residual, then the model structure is rejected as false, and a new model is tried until a fit between the observed and calculated structure factors yields an acceptable residual (R < 0.25). (Other models were tried for this complex, but they either gave Fourier maps which were uninterpretable or they converged to the present model). However, the normal crystal structure is solved with data obtained from crystals which have dimensions of the order of 0.1 mm. In the crystals available for this experiment, two of the dimensions were of the order of 0.01 mm. Thus, long exposures were required to give a small number of relatively weak diffraction spots. (Each Weissenberg photograph was exposed for five days with Cuka radiation 50 kv., 20 ma. loading, in a helium atmosphere). 

X-ray diffraction studies were carried out using CuKa radiation and a graphite monochromator using the conventional techniques for powder samples. 

FTIR spectra were recorded with an Impact 410 (Nicolet) spectrometer. Powder X-ray diffraction data were obtained on a Siemens D 5005 diffractometer in the Bragg-Brentano geometry arrangement using CuKa radiation. Adsorption isotherms of nitrogen at -196 °C... 

Powder X-ray diffraction patterns (XRD) for saponite and the corresponding PCH derivative were measured on Rigaku Rotaflex diffractometer equipped with a rotating anode under 45 kV and 100 mA and CuKa radiation (A = 1.542 nm). The scattering and receiving slits were 1/6 and 0.3 degrees, respectively. 

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