Recording system sensitivity

The X-ray diffraction method utilizes a monochromatic beam of X-rays to which a solid material is exposed. The beam of radiation interacts with the solid, and is both reflected and diffracted. The reflection pattern is recorded by a detector system sensitive to the X-radiation. Until recently, this involved an intricate mechanical device whose complex... 

For measuring the RTD of a very fast-moving phase, the sensitivity and the response time of the tracer-concentration recording equipment may be a problem. A radioactive tracer offers an advantage in that the scintillation detection counter can be interfaced with very rapid recording systems or multichannel analyzers. 

The presence of a metal on the sensor s sensitive element is usually simply related to the presence of electrodes, which guarantee the electrical continuity of the data-recording system. These electrodes, however, do have an active role in the setup, although their physico-chemical role is not alw s clear. 

Another novel recording system has been proposed wherein electrochemi-cally induced acids and bases promote the alternate intercalation of fluoran dye and tetra-n-decylammonium ions, along with a color change of the dye, in the acetone-clay suspension (299). Designing more electrochemically sensitive recording layers and suppressing any decomposition will be required to improve the performance. 

The principles of the laser-excited atomic fluorescence (LEAF) technique are very simple. A liquid or solid sample is atomized in an appropriate device. The atomic vapor is illuminated by laser radiation tuned to a strong resonance transition of an analyte atom. The excited analyte atoms spontaneously radiate fluorescence photons and a recording. system registers the intensity of fluorescence (or total number of fluorescent photons). The extremely high spectral brightness of lasers makes it possible to saturate a resonance transition of an analyte atom. Therefore, the maximum fluorescence intensity of the free analyte atoms can be achieved while the effect of intensity fluctuations of the excitation source are minimized. Both factors provide the main advantage of LEAF— extremely high sensitivity. The best absolute detection limits achieved in direct analysis by LEAF... 

Modern microbalances, especially the magnetic suspension balances are fairly complex systems which often are sensitive to electromagnetic or - to lesser extend - mechanical disturbances from outside. Oscillations of the basement caused by nearby subways or trucks may cause disturbances, though balances recently (2002) have become less sensitive to these. However, electromagnetic fields radiating from electric heating systems or other wires inside a lab can lead to serious problems in the performance of either the balance itself or the data recording system. 

Notes. (1) The sensitivity of the recording system should be chosen so that the height of the wave corresponding to the reduction of cobaltous ions (the second step, at — 1-OV) is about one fifth of the full scale deflection. 

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