Sapphire-cell system

In conclusion, sapphire cell systems, as well as other systems to increase the filling factor in the NMR detection coil, allow a detection of pressure effects in peptides and proteins with a much higher sensitivity than that obtained in conventional systems and should allow the application of most modern experiments in multidimensional high-resolution NMR spectroscopy at elevated pressures. 

We performed transient absorption measurements on BP(OH>2 with a spectrometer based on two noncollinearly phase matched optical parametric amplifiers (NOPAs) pumped by an homebuilt regenerative Ti Sapphire laser system or a CPA 2001 (Clark-MXR) [1,7]. The tunable UV pump pulses are generated by frequency doubling the output of one of the NOPAs. The other NOPA provides the visible probe pulses. The cross correlation between pump and probe pulses has a typical width (FWHM) of 40 fs. The sample is a cyclohexane solution of BP(OH)2 pumped through a flow cell with a 120 pm thick channel. 

Human skin cells (keratinocytes) were tested [5] in vitro for their ability to differentiate after exposure to 0.1-3 THz radiation generated by two different pulsed Ti Sapphire laser systems. The first generated THz by directing 20 ps laser pulses onto an electro-optic... 

Fig. 22. Low-frequency spectra of Mb obtained with Soret excitation (a) MbCO photo-lyzed with 20-30 psec pulses, (b) MbCO photolyzed with 10 nsec pulses of approximately 435 nm from the 10 Hz output of a Nd YAG laser system (average energy 1.0-1.5 mJ/ pulse), and (c) spectrum of deoxyMb taken under same conditions as in (b). Asterisks denote Raman lines of the sapphire cells used in the nanosecond experiments. (From Findsen et al. )...

Information exists about the use of measuring cells made entirely of diamond or graphite with or without embedded diamond windows. Diamond cells were used, for instance, by Toth and Gilpatrick [333] in the investigation of the Nb(IV) spectrum in a LiF - BeF2 molten system at 550°C. Windowless graphite cells for the IR spectroscopy of melts were developed by Veneraky, Khlebnikov and Deshko [334]. Diamond, and in some cases windowless sapphire or graphite micro-cells, were also applied for Raman spectroscopy measurements of molten fluorides. 

Figure 6.7 A typical batch reactor used for small-scale laboratory reactions. The view through the cell is shown (a) together with the dismantled cell (b) Here, the screw thread which holds the window in place can be seen, along with the sapphire window. The holes on top of the cell allow it to be connected to the high-pressure system with the relevant adaptors. (Photograph by Dr A. P. Abbott)...

It can be used under very high pressure and temperatures. Oil reservoirs are found typically at 100°C and 300 atm pressure. The surface tension of such systems can be conveniently studied by using high pressure and temperature cells with optical clear windows (sapphire windows 1 cm thick up to 2000 atm). For example, yof inorganic salts at high temperatures (ca. 1000°C) can be measured using this method. The variation in surface tension can be studied as a function of various parameters (temperature and pressure additives [gas, etc.]). 

Depth scale calibration of an SIMS depth profile requires the determination of the sputter rate used for the analysis from the crater depth measurement. An analytical technique for depth scale calibration of SIMS depth profiles via an online crater depth measurement was developed by De Chambost and co-workers.103 The authors proposed an in situ crater depth measurement system based on a heterodyne laser interferometer mounted onto the CAMECA IMS Wf instrument. It was demonstrated that crater depths can be measured from the nm to p,m range with accuracy better than 5 % in different matrices whereas the reproducibility was determined as 1 %.103 SIMS depth profiling of CdTe based solar cells (with the CdTe/CdS/TCO structure) is utilized for growing studies of several matrix elements and impurities (Br, F, Na, Si, Sn, In, O, Cl, S and ) on sapphire substrates.104 The Sn02 layer was found to play an important role in preventing the diffusion of indium from the indium containing TCO layer. 

The last ATR cell described here in detail was designed for the study of catalytic reactions at high pressures and in particular in supercritical fluids. A schematic representation of the design is shown in Fig. 17 (76). An important issue in this type of reaction is the phase behavior of the system, which can have a large influence on the catalytic reaction 77,IS). The cell consists of a horizontal stainless-steel cylinder. It is designed to allow monitoring of the phase behavior via a video camera. For this purpose, one end of the cylinder is sealed with a sapphire window, behind... 

Accurate self-consistent thermochemical data for the copper chlorides up to 200°C are required, in order to improve solubility calculations and electrochemical modelling capabilities for Aspen Plus and OLI software. Experimental work has been initiated at the University of Guelph, Canada and UOIT to determine a comprehensive thermochemical database, for solubility limits of OMIT, and aqueous cupric chloride versus chloride concentration and temperature using UV-VIS spectroscopy (Suppiah, 2008). The chloride ion is obtained by adding LiCl OMIT. The conditions of tests are primarily 25-200°C, up to 20 bars. Specialised equipment for this task is needed to reach elevated temperatures and pressures, because cupric chloride is chemically aggressive, and because changes in the solution concentrations must be made precisely. A titanium test cell has been custom made, including a UV-VIS spectrometer with sapphire windows, HPLC pumps and an automated injection system. The data acquired will be combined with past literature data for the cuprous chloride system to develop a self-consistent database for the copper (I) and copper (II) chloride-water systems. 

An enormous range of properties is found in oxides. The most successful and most widely used substrate for GaN to date is sapphire, AI2O3. Except for wurtzite materials, few of the unit cells in these materials match with GaN, but it is usually useful to think of these systems as having a close-packed nitrogen lattice in GaN matching to a near close-packed oxygen lattice in the oxide. 

The phase equilibria unit shown in picture 3 is a useful completion for the SFE pilot units. It is built for measurements and detection of phase equilibria and phase transitions by optical and analytical means. The picture from the optical cell is transmitted through the sapphire windows by the directly connected camera system and is displayed on the monitor in the front panel. Whenever samples are drawn out of the cell the directly connected counterbalance piston moves, thus keeping the pressure in the cell constant even during sampling operations. 

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