Sample chamber

For low pressure pipelines that have ports open to the atmosphere, eg, sewers or closed effluent culverts, samplers are designed to sample through manholes. In a typical system, the Hquid is lifted through a suction line into the sampling chamber under vacuum. When filled, the vacuum shuts off, and the sample drains into a sample jar. A secondary float prevents any Hquid from reaching the vacuum pump. The suction line then drains by gravity back to the source. 

With a special optical system at the sample chamber, combined with an imagir system at the detector end, it is possible to construct two-dimensional images of the sample displayed in the emission of a selected Raman line. By imaging from their characteristic Raman lines, it is possible to map individual phases in the multiphase sample however, Raman images, unlike SEM and electron microprobe images, have not proved sufficiently useful to justify the substantial cost of imaging optical systems. 

The maximum sample size is limited only by the design of the sample chamber. Typically, samples up to several cm in diameter can be accommodated. A diameter of a few mm is generally the lower limit because high-energy ion beams focused through standard beam optics are on the order of a few mm in diameter however, microbeam setups permit the use of samples an order of magnitude smaller. 

When measuring CO concentration, the reference signal is obtained when the beam is passed through the sample chamber and the CO cell. The absorption is then saturated due to the high CO concentration in the cell. Consequently, the reference signal is practically nondependent on the CO concentration in the sample gas. When the beam passes through the sample chamber and the N2 filter, the absorption is dependent on the CO concentration in the sample chamber, as the N2 filter does not absorb energy from the infrared beam. 

It is a disadvantage of all photomultipliers that the photocurrent is not completely proportional to the strength of illumination. Further, the photocurrent must not exceed 10 A or the photomultiplier becomes fatigued. Daylight switches are incorporated into some scanners for this reason in order to prevent over-illumination of the detector when the sample chamber is opened. 

The advantage of the stoichiometric technique is that it is extremely simple. Care has to be taken to remove all gases dissolved in the IL sample initially, but this is easily accomplished because one does not have to worry about volatilization of the IL sample when the sample chamber is evacuated. The disadvantage of this technique is that it requires relatively large amounts of ILs to obtain accurate measurements for gases that are only sparingly soluble. At ambient temperature and pressure, for instance, 10 cm of l-n-butyl-3-methylimida2olium hexafluorophosphate ([BMIM][PFg]) would take up only 0.2 cm of a gas with a Henry s law constant of... 

Limitations. Most commercial cytometers require 5-60 s to pressurize the cell sample and deliver it to the point of analysis. We developed a special sample chamber which delivers sample in three seconds in some machines (25). The fact that commercially available software has only recently been written and the reluctance of instrument manufacturers to make available source code has probably delayed by a few years the widespread application of this technology. 

Figure 4-8. Basic components of a simple mass spectrometer. A mixture of molecules is vaporized in an ionized state in the sample chambers.These molecules are then accelerated down the flight tube by an electrical potential applied to accelerator grid A. An adjustable electromagnet, E, applies a magnetic field that deflects the flight of the individual ions until they strike the detector, D.The greater the mass of the ion, the higher the magnetic field required to focus it onto the detector.

Figure 8.2 Different apparatus used for steu distillation. A aodified Gaman steam distillation apparatus A, steam generation flask B, sample chamber C, splash head D, condenser B, delivery tube F, separatory funnel. B = micro steam distillation apparatus A, boiling flask B, collection bulb C, water return arm D, Condenser. C - steam distillation apparatus using a Dean and Stark type trap. D = Nielsen-Kryger steam distillation apparatus.

Leaf water potential and osmotic potential were measured using a Wescor Dewpoint Microvoltmeter (Model HR-33) coupled with C-51 and C-52 sample chambers. Two plants from each group were sampled each day by taking two 7-mm diameter leaf disks from each plant, one for water potential and one for osmotic potential. Plants from which leaf disks were obtained were discarded. The water potential of a leaf disk was read following a 2-hr equilibration period in a sample... 

ESCA core-level spectra for and 0 g were recorded with a Leybold-Heraeus Spectrometer using AIKq excitation radiation. Typical operating conditions for the X-r3y gun were 13 kV and 14 mA and a pressure of 3x10 mbar in the sample chamber. 

Focusing Elements. Two ion optical components are usually placed between the accelerator and the sample chamber. A magnetic field separates any He-, He, or He+ from the He++ beam. A quadrupole magnetic lens then shapes the beam and focusses it into the sample chamber. 

Sample Chamber and Detector. The pressure in the sample chamber is typically 10-6torr, although UHY may be required for some experiments. The samples are usually mounted on a five-axis goniometer, so that a series of samples may be loaded and analysed sequentially. The goniometer can tilt and rotate the samples relative to the direction of the incident beam. Comparing spectra obtained at different incident and exit beam angles provides fuller characterization of the sample composition as a function of depth. The samples can be electrical insulators... 

By adding accessories to the sample chamber, or by changing the operating procedures, several other experiments can piggy-back on to the RBS analysis. For example HIBS, HFS, PIXE, NRA, CPAA and PIGE may all be accessible using a given particle accelerator. 

Figure 4.10. Beamline BW4 at HASYLAB. View from a sample chamber along the vacuum tube towards the detector at the opposite yellow wall... 

The sample chamber contains the material that is studied in the experiment and provides for its manipulation and processing during the experiment. Figure 4.10 shows a typical sample chamber mounted at beamline BW4 of HASYLAB, Hamburg. 

The construction of sample chambers is constrained by the height and the width of the bars from the optical bench... 

These disadvantages are overcome by the so-called dance-floor principle which is supposed to become the major beamline construction principle of the future. Figure 4.11 shows a dance floor during the construction of the beamline hall at the ANSTO neutron-scattering facility at Lucas Heights near Sydney, Australia. The dance floor is featuring an extremely plane and hard floor surface from granite. Optical components, detectors and sample chambers are mounted on supports with a flat lower surface. While compressed air is blown into the gap between the dance floor and the area of support, components are easily moved and adjusted in the optical beam path. 

If a processing apparatus is constructed in such a way that the X-ray beam can irradiate the sample, it can most probably be mounted in the beamline. Suitable chambers allow for a change of sample temperature, humidity, strain, pressure, etc. Melts may be sheared during irradiation. Fibers can be spun in the beam. Several methods may be combined (SAXS, WAXS, calorimetry, light scattering) by utilization of sophisticated sample chambers. 

In order to reduce air absorption in SAXS and USAXS setups, a vacuum tube (cf. Fig. 4.10) is mounted between sample chamber and detector. 

Silicon profile formed at 500eV.(a) An ion beam composed of Ar Xe+, XeF2+ (b) CAIBE with an Ar+ beam in conjunction with XeF2 in the sample chamber. 

With slide clip in open position, the labeled glass slide and the sample chamber are fit against the slide clip. The spring clip is brought up and secured under the two retaining hooks. 

The assemblies of slide clip, glass slide, and sample chamber is inserted into the sealed head of the cytocentrifuge. 

Three to five drops of the now homogeneous cell suspension are placed into the sample chamber. 

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