Array Spectrometers

Figura 3 Grating spectrometers commonly used for ICP-OES (a) monochromator, in which wavelength is scanned by rotating the grating while using a singie photomultiplier tube (PMT) detector (b) polychromator, in which each photomultiplier observes emission from a different wavelength (40 or more exit slits and PMTs can be arranged along the focal plane) and (c) spectrally segmented diode-array spectrometer.

The scope of UV analysis of dissolved polymer/additive matrices is thus quite restricted and mainly limited to special cases in which the additive package is known, e.g. the determination of Irganox 1098 in GFR-PA4.6 after dissolution in H2SO4/HNO3. Fibre-optic dissolution analysis by means of a UV diode array spectrometer is well known. In comparison to IR spectroscopy, UV spectrophotometry is better equipped to provide quantitative data. 

Figure 8.5. Palm of the hand. Fluorescence spectrum (Fb-mode, full line) and diffuse reflectance absorption spectrum (dashed line, normalized to X = 700 nm, reference filter paper) measured with a sensitized diode array spectrometer.

Figure 8.7. Delayed fluorescence and diffuse reflectance transient absorption spectroscopy on scattering substrates. Example terthicnyl on silica gel excited with = 354 nm (neodymium/yttrium-aluminum-garnet) (Nd/YAG) laser pulse of 10 nsec, 20 mj), recorded with a gated diode array spectrometer.

At Merck KGaA in Darmstadt (Germany), in-line UV spectroscopy has been used for monitoring a distillation setup for solvent purification." A transmission probe was implemented at the top of the column. Solarization-resistant UV fibers guided the light to a diode array spectrometer. From the spectra, a quality parameter was extracted and fed to the process control system (PCS). As an example, the quality parameter would exhibit a transient behavior upon column startup. Below a defined threshold value of the parameter, the PCS would assume sufficient product quality and switch the exit stream from waste to product collection. The operation of the spectrometer does not take place in a direct manner, but rather via the PCS. 

E.W. Stark, Near-infrared array spectrometers, in Handbook of Vibrational Spectroscopy, J.M. Chalmers and PR. Griffiths (eds), vol 1, John Wiley Sons, New York, 2002. 

H. Keutel, J. Gobel and V. Mehta, NIR diode array spectrometer in pharmaceutical production control, Chemie Technik 32, 48-50 (2003). 

M. Glick, K. R. Brushwyler and G. M. Hieftje, Multivariate calibration of a photodiode array spectrometer for atomic emission spectroscopy, Appl. Spectrosc., 45, 1991, 328-333. 

This type of instrument resembles a spectrograph because it allows the simultaneous measurement of all wavelengths. It uses an array of up to 2 000 miniaturised photodiodes (Fig. 11.13). A full spectrum can be recorded in milliseconds with this type of simultaneous acquisition detector, each diode measuring the light intensity over a small interval of wavelength. The resolution power of these diode-array spectrometers is limited (usually 1 to 2nm) by the size of the diodes. 

The way we know which peak is which is to record the entire ultraviolet spectrum of each peak as it is eluted, using a photodiode array spectrometer. 

Stark, E.W., Near-Infrared Array Spectrometers. In Chalmers, J.M. and Griffiths, P.R. (eds), Handbook of Vibrational Spectroscopy, vol 1 John Wiley 8c Sons New York, 2002, pp. 393-422. Goldman, D.S., Near-Infrared Spectroscopy in Process Analysis. In Meyers, R.A. (ed.), Encyclopedia of Analytical Chemistry, vol 9 Process Instrumental Methods John Wiley 8c Sons New York, 2000, pp. 8256-8263. 

Sullivan, J.J. and Quimby, B.D. (1990) Characterisation of a computerised photodiode array spectrometer for gas chromatography. Anal. Chem., 62, 1034-1043. 

A Dual-Beam Photodiode Array Spectrometer System for Liquid Chromatographic Separation Methods Development... 

The set-up used consists of a tungsten light source (20 W, 12 V), optical Y-fibre couplers (PMAA, 1 mm core diameter, microparts, Dortmund, Germany) and a diode array spectrometer (MMS, Zeiss, Jena, Germany). Interference spectra were recorded from 450-700 nm. 

Spange (2002). A diode array spectrometer with glass fiber optics was used to measure adsorbed species through a quartz window in the bottom of the reactor after sedimentation of the particles. Tromp et al. (2003) also mentioned an optical fiber probe for such an analysis. 

FIGURE 63 Schematic of a HERFD crystal array spectrometer, in this case using six spherically bent Ge(620) crystals to collect the Fe Kf region with approximately 1.0 eV resolution. The inset (left) shows the Rowland circles for each analyzer crystal (Heijboer et al., 2004). Reprinted with permission from (Heijboer et al., 2004). Copyright 2004 American Chemical Society. 

Diode array spectrometer spectrometer Diosmosis - osmosis... 

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