Spectroscopic Devices

There are many examples of on-chip spectrometry in the literature. Some of these are described below. 

Most examples in the literature exploit electrospray ionisation but some research groups have reported the use of atmospheric pressure chemical ionisation (APCI) on-chip. In one such example, the chip was composed of two wafers, one made of silicon wafer one made of pyrex glass . The silicon wafer contained the nebuliser gas inlet, vapouriser channel and a nozzle. The sample inlet from the LC column was directly connected to the 

Microfluidic chips and Compact disks have also been successfully coupled with MALDI-TOF mass spectrometry . 

Another commercial system for proteomics research is the TriVersa NanoMate from Advion BioSciences Inc. It integrates LC-MS, fraction collection and chip-based infusion in one platform. Use of such chip systems is widespread in the literature . 

At the University of Twente in the Netherlands, a multichannel chip has been designed with an integrated NMR detection coil and has yielded promising results at low field 

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In order to study the variation of the concentration of ions during and after polymerisation, we scanned the solutions at 424 mp. against time. We found that, in addition to the SD ions, several other species giving peaks in the visible were formed at the end of the polymerisation. Therefore the kinetic study on the formation of the SD ions had to be supplemented by repeated scannings of the full visible and UV spectra. Some of the experiments carried out in the spectroscopic device were repeated in the conductivity cell. In view of the rather complicated behaviour of the system after the end of the polymerisation, we shall first give a chronological account of the phenomena, and then discuss their quantitative aspects. Figure 1 illustrates the different phases of the reaction from a spectroscopic point of view. 

A diode array is a spectroscopic device ior the continuous monitoring of absorbance over a specified wavelength, range. 

Rare-gas samples exist only at cryogenic temperatures and most of the optical spectroscopy of electronic processes should be done in the vacuum ultraviolet. Making experiments requires an indispensable combination of liquid-helium equipment with windowless VUV-spectroscopic devices and synchrotron radiation as a photon source. To study the electronic excitation energy pathways and a variety of subthreshold inelastic processes, we used the complimentary advantages of cathodoluminescence (possibility to vary the excitation depth beneath the sample surface), photoluminescence (selective-state excitation by synchrotron radiation at high-flux SUPERLUMI-station at HASYLAB, DESY, Hamburg) and... 

Spectroscopy is the measurement of electromagnetic radiation absorbed, scattered, or emitted by chemical species. Because different chemical species and electromagnetic radiation interact in characteristic ways, it is possible to tailor instrumentation to detect these interactions specifically and quantitatively. A simple absorption spectrophotometer, depicted schematically in Figure 12.2, contains components that are common to many spectroscopic devices and are representative of many of the basic principles of instrumentation found in analytical biochemistry. 

The measured peak absorption coefficient, Kmax, for a discrete impurity transition depends on the oscillator strength of the transition and on the impurity concentration. The measured profile of a recorded line is the convolution product of its true profile by the instrumental function of the spectroscopic device used. It depends significantly on the ratio of the true FWHM of the line to the spectral resolution (the spectral band width) of the spectroscopic device. When this ratio is of the order of 3 or above, the measured FWHM can be considered as the true FWHM and the observed profile is close to the true profile. For lower values of this ratio, the measured FWHM increases steadily while the measured value of Kmax decreases, and it is assumed that when the ratio becomes l/3 or smaller, the measured FWHM is the spectral resolution and the measured profile the instrumental function. This effect is known as instrumental broadening. For isolated lines, the absorption coefficient can be integrated over the entire line to give an integrated absorption I A ... 

Gamma-ray spectroscopic devices, although being rather expensive, are available in the market with very high standards of performance and quality assurance. 

At a time when companies are reducing their workforces, competition and regulations are requiring more, not less, testing of the product. The fortunate coincidence is that there is a concomitant increase in the speed and accuracy of spectroscopic devices for process control. This trend will lead to more measurements of higher quality, allowing manufacturers to control their products in real time. Thus, higher quality, less expensive products will be the result of this revolution. 

The tower was also used for visualization of sprays by high-speed videography. Spray droplet size distributions were measured by a laser diffraction spectroscopic device (Spraytec Malvern Instruments). A set of experiments was performed and in triplicate for the same emulsion. The standard deviation of mean drop size of the same emulsion at similar processing conditions within such triplicate experimental series was found to be < 2 %. 

Miniaturization of HSIs is also the subject of advanced research as shown by the patent filed by Majumdar etal. [195], which describes a spectroscopic device that can be used to acquire single-frame spatial, spectral, and polarization information of an object. One can also hope that the substantial progress made in sensor miniaturization will lead to the design of smart phones equipped with HSIs. 

In the clinical environment, optical techniques have been used for decades (microscope, colposcope, ophthalmoscope, endoscope, laparascope). Integration of spectroscopic devices into existing procedures is an obvious task. Fibre optic cables provide a flexible solution for adequate optical interfacing between the optical and spectroscopic device and the sample to be interrogated in situ. Fibre optic probes can be inserted into cavities and tubular structures, put in contact with epithelial surfaces and also inserted into structures that can be punctuated by rigid devices such as needles. Fibre optic devices for optical spectroscopy can be manufactured as flexible catheters with an outer diameter not exceeding 0.5 mm. We will present in this article fibre optic solutions for... 

Figure 3. Diffraction gratings operate in reflection or transmission. In spectroscopic devices, such as monochromators, reflection gratings play key roles.

A.M. Mohs, M.C. Mancini, S. Singhal, J.M. Provenzale, B. Leyland-Jones, M.D. Wang, S.M. Nie, Hand-held spectroscopic device for in vivo and intraoperative tumor detection contrast enhancement, detection sensitivity, and tissue penetration. Anal. Chem. 82, 9058 (2010)... 

The focus of this chapter is photon spectroscopy, using ultraviolet, visible, and infrared radiation. Because these techniques use a common set of optical devices for dispersing and focusing the radiation, they often are identified as optical spectroscopies. For convenience we will usually use the simpler term spectroscopy in place of photon spectroscopy or optical spectroscopy however, it should be understood that we are considering only a limited part of a much broader area of analytical methods. Before we examine specific spectroscopic methods, however, we first review the properties of electromagnetic radiation. 

It is the use of LIDAR devices as tools for spectroscopic measurements on the various gases present in the atmosphere which concerns us here. These include ozone, carbon dioxide, the CFCs (chlorofluorocarbons, such as CFC-11, trichlorofluoromethane, and CFC-12, dichlorodifluoromethane, used as refrigerants) and all those molecules regarded as atmospheric pollutants. 

In the near-infrared, Al Ga As and In Ga As P lasers, and in the far-infrared lead compound semiconductor lasers are tunable by varying temperature and operating current. Many exceUent spectroscopic studies have been performed using them. However, they do have relatively limited tuning ranges for any one device. 

TLC plates are of particular interest as substrates for spectroscopy (i) as a storage device for offline spectroscopic analysis (ii) for efficient in situ detection and identification and (iii) for exploitation of spectroscopic techniques that cannot be used in HPLC. Thin-layer chromatography combined with HR MAS (NMR) can be used for compound identification without the need for elution from the stationary phase [413]. Recently also TLC-XRF was found suitable for in situ TLC imaging of elements [414]. The combination... 

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