Simultaneous spectrometer

Simultaneous spectrometers consist of various combinations of analyser crystals and detectors, arranged around the sample at fixed angle settings. Use of a multichannel X-ray spectrometer with simultaneous determination of up to 24 elements can considerably increase the analysis speed (a few seconds to a few minutes). 

Model Perkin Elmer Optima 4300DV (Simultaneous Spectrometer)... 

X-ray spectroscopy is nowadays applied mostly in the form of X-ray fluorescence, where scanning monochannel machines, sequence spectrometers and simultaneous spectrometers are used in wavelength dispersive X-ray fluorescence. The introduction of bent analyser-crystals extended the method to smaller samples, thus marking another step toward microprobe analysis. 

Cho et al. [280] compared dc and rf gas jet-boosted GD-AES for the analysis of steel in terms of the voltage-current relationship they studied the effects of the gas flow-rate (0-800 ml/min) and pressure (3-5 torr) on the dc bias potential, sample weight loss and emission intensity. The use of a simultaneous spectrometer for the rf mode proved dispensable by virtue of the high stability (variations less than 0.3%) for both matrix and trace elements. Both the rf and the dc mode provided calibration graphs that were linear over two or three decades (or even more if the analytical signal was normalized to the signal of a matrix component) however, the limits of detection obtained in the rf mode for many trace elements in steel were at the level of tens of ppb, which was an order of magnitude better than in the dc mode. 

For ICP-AES both sequential and simultaneous as well as combined instruments are used. In sequential spectrometers special attention is given to the speed of the wavelength access and in simultaneous spectrometers to the provision of background correction facilities. In combined instruments a number of frequently used channels are fixed and with a moving detector or an integrated monochromator... 

Single beam, reverse optic simultaneous spectrometer... 

In principle the combination of fibre optics and photodiode array spectrometers shows great advantages in photokinetics. Fibre optic technology allows a wide variation of such set-ups. In the 1960s one tried to achieve a versatile spectrometer by combining modules such as light source, monochromator, cell compartment, and detector on an optical bench. This arrangement of the different components allowed the measurement of absorbance, fluorescence, and reflectance. The same can be achieved nowadays by the use of a so-called simultaneous spectrometer module, schematically presented in Fig. 4.11. 

The analyzing crystal shown schematically in Fig. 8.14 has a flat surface. Flat crystals are used in scanning (sequential) spectrometers. Curved crystals, both natural and synthetic multilayers, are used in simultaneous spectrometers, electron microprobes, and for synchrotron X-ray spectrometry. The advantage to a curved crystal is that the X-rays are focused and the collimators replaced by slits, resulting in much higher intensities than with flat crystal geometry. This makes curved crystals excellent for analysis of very small samples. The use of a curved crystal and slits in a simultaneous spectrometer is illustrated schematically... 

A spectrometer consists of three main parts (1) an emission source, which produces the spectrum (2) an optical system, which scatters the spectrum and (3) a device to measure the emitted lines. The two major types of instrument for the analysis of emission spectra are sequential and simultaneous spectrometers, although there are many variants of each in terms of mechanical and optical characteristics. The spectral... 

There are three types of WDXRF instruments sequential spectrometers, which use a goniometer and sequentially measure the elements by scanning the wavelength simultaneous spectrometers, which use multiple channels, with each channel having its own crystal/detector combination optimized for a specific element or background measurement and hybrid spectrometers, which combine sequential goniometers or scanners with fixed channels as well as XRD channels and goniometers. Hybrid instruments will be discussed in Section 8.4 with XRD instruments. 

Photodiodes, on the other hand, use the internal photoelectric effect [77]. When these diodes are arranged in arrays, they are known as diode arrays or diode matrices. Multiplex detectors are used in simultaneous spectrometers [80]. 

Simultaneous Spectrometers. Modem simultaneous spectrometers use photoelectric radiation detection rather than the photographic plates formerly used for qualitative and semi-quantitative analyses. Simultaneous photoelectric spectrometers mostly have a Paschen -Runge optical mounting. They have many exit slits and are especially suitable for rapid determinations of many elements in a constant, well-characterized matrix the achievable precision is high. However, the... 

A Charge-lnjectioii Device Instrumeat. A number of companies offer multichannel simultaneous spectrometers based on echelle spectrometers and two-dimensional array devices. This type of instrument has replaced other types of multichannel emission spectrometers in many applications. 

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