Regions vacuum ultra-violet

Electromagnetic radiation of such high energy falls within the Vacuum ultra-violet (VUV), X-ray and y-ray regions of the spectrum. They are called ionizing radiations and their effects on matter are part of the science of radiation chemistry. 

Complete MCP s can be stacked to provide even higher gains. For response in the vacuum ultra-violet spectral region (50-200 nm) a SSANACON, self-scanned anode array with microchannel plate electron multiplier, has been used (36). This involves photoelectron multiplication through two MOP S, collection of the electrons directly on aluminum anodes and readout with standard diode array circuitry. In cases where analyte concentrations are well above conventional detection limits, multi-element analysis with multi-channel detectors by atomic emission has been demonstrated to be quite feasible (37). Spectral source profiling has also been done with photodiode arrays (27.29.31). In molecular spectrometry, imaging type detectors have been used in spectrophotometry, spectrofluometry and chemiluminescence (23.24.26.33). These detectors are often employed to monitor the output from an HPLC or GC (13.38.39.40). 

The spectral range of interest for AAS spans from the near infrared (852.1 nm for Cs) to the vacuum ultra violet (193.6 nm for As). A monochromator is a device which separates, isolates, and controls the intensity of a narrow region of the radiant energy which is transmitted to the detector (characterised by its spectral slit width). It consists of an entrance slit, a dispersing unit (a diffraction grating) and an exit slit. The greater the intensity of the radiation transmitted to the detector the lower the signal amplification required (which contributes to electronic noise). However, the entrance and exit slits must be of similar mechanical widths (aperture size) so that, in practice, a compromise must be chosen (slit width versus narrow... 

The usefulness of the modern spectrophotometer is made greater by the availability of a number of accessories and attachments. Attachments are available for measuring reflectance of diffusely reflecting materials, and for fluorescence spectra. Attachments have been described for commercial spectrophotometers in order to cover the vacuum, ultra-violet region down to 170 mfi. Some instruments which cover the range from vacuum ultra-violet to visible are commercially available. 

Direct estimation of P by this method presents difficulties, however, due to the fact that the absorption lines lie in the vacuum ultra violet region at 177,178,179 and 213 nm. More practical methods are based on the formation of coloured phosphate complexes which are discussed below. There is a simple... 

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