Infrared, detection

Infrared detection of toluene can be achieved on a microchip. The chip substrate, which should be IR-transparent, has been fabricated from CaF2. The microchannels were etched on CaF2 using a saturated Fe(NH4)(S04)2 solution at room temperature for 24 h. The etched depths were -18 im or - 8 im, when the etchant was stirred or unstirred, respectively. Bonding was achieved using photoresist as an adhesive layer and with heating (135°C, 30 min) [743,744], 

Pyroelectric materials are used mainly for the detection of infrared radiation. The elements for the detectors are typically thin slices of material (e.g. 1.0 x 1.0 x 0.1 mm) coated with conductive electrodes, one of which is a good absorber of the radiation. 

If it is assumed that all the power absorbed in time dt is rapidly distributed through the volume of the element, its temperature will rise by d T where 

In this equation H = pcAh is the heat capacity of the element where c is the specific heat of the pyroelectric material and, in this context, p is its density. In what follows the product pc, the volume specific heat, is given the symbol c.  

If part of the absorbed power is lost to the surroundings by reradiation, conduction or convection at a rate G per unit temperature excess of the element over its surroundings, Eq. (7.5) is modified to 

To obtain a continuous response from a pyroelectric material the incident radiation is pulsed, and this situation is analysed by assuming that the energy varies sinusoidally with frequency co and amplitude W0. Equation (7.6) then becomes 

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Infrared absorption Infrared cameras Infrared detection Infrared detector Infrared detectors... 

Mercury Telluride. Compounds of mercury with tellurium have gained importance as semiconductors with appHcations in infrared detection (9) and solar cells (10). The ratio of the components is varied, and other elements such as cadmium, zinc, and indium are added to modify the electronic characteristics. 

AlGaAs quantum well infrared photodetector (QWIP) focal planes have achieved sufficient sensitivity out to 10-p.m wavelength to result in scene temperature sensitivity of ca 0.2°C when the focal plane is cooled to 77 K. Spectral sensitivity is shown in Eigure 9c and array information is given in Table 1. The supedattice, a newer tool for achieving controlled activation energy, should present many alternative infrared detection techniques. 

Stability, and can provide both ohmic low resistance contacts and rectifying contacts. Typically, siUcide layers are formed in situ by sputteriag a thin platiaum layer onto the siUcon surface, followed by sintering. Infrared detection is another appHcation of platiaum siUcide technology. 

DEVELOPMENT OF INFRARED DETECTION IN FLOW INJECTION ANALYSIS (FIA) AND CAPILLARY ELECTROPHORESIS (CE)... 

N. Ragunathan, T. A. Sasaki, K. A. Rrock and C. A. Wilkins, Multidimensional fast gas chromatography with matrix isolation infrared detection . Anal. Chem. 66 3751-3756 (1994). 

In conclusion, IR analysis of polymer/additive extracts before chromatographic separation takes advantage mainly of straightforward transmission measurements. Without separation it is often possible to make class assignments (e.g. in the reported examples on plasticisers and carbodiimide hydrolysis stabilisers) it may eventually be necessary to use multivariate techniques. Infrared detection of chromatographic effluents is dealt with in Chapter 7. 

Principles and Characteristics Fourier-transform infrared detection in SFC is attractive because it can offer structural information about the analytes [372]. The coupling was introduced in 1983 [373]. Various approaches have been advanced ... 

The deprotection of carbobenzyloxy protected phenylalanine was carried out in a low-pressure test unit (V= 200 ml) equipped with a stirrer, hydrogen inlet and gas outlet. The gas outlet was attached to a Non Dispersive InfraRed (NDIR) detector to measure the carbon dioxide. During the reaction the temperature was kept at 25 °C at a constant agitation speed of 2000 rpm. In a typical reaction run, 10 mmol of Cbz protected phenylalanine and 200 mg of 5%Pd/C catalyst were stirred in a mixture of 70 ml ethanol/water (1 1). The Cbz protected phenylalanine is not water-soluble but is quite soluble in alcoholic solvents conversely, the water-soluble deprotected phenylalanine is not very soluble in alcoholic solvents. Thus, the two solvent mixture was used in order to keep the entire reaction in the solution phase. Twenty p.1 of the corresponding modifier was added to the reaction mixture, and hydrogen feed was started. The hydrogen flow into the reactor was kept constant at 500 ml/minute and the progress of the reaction was monitored by the infrared detection of C02 in the off-gas. 

Liquid chromatography (LC) encompasses several techniques, which includes HPLC and SEC (sometimes referred to as GPC). Many variants of and developments from these techniques exist, and are used in the study and analysis of polymer degradation/oxidation. As discussed earlier, SEC is often coupled with MALDI-ToF-MS to facilitate the identification of the products of polymer degradation. SEC has also been coupled with mid-infrared detection and similarly used for studies of polymer degradation. SEC/GPC is discussed further below. 

Floyd TM, Schmidt MA, Jensen KF (2005) Silicon micromixers with infrared detection for studies of liquid-phase reactions. Ind Eng Chem Res 44 2351-2358... 

Wiebolt RC, Adams GE, Later DW. 1988. Sensitivity improvement in infrared detection for supercritical fluid chromatography. Anal Chem 60 2422-2427. 

To further elucidate the details of the pure NaNT to DBX-1 reaction progress, various reactions to DBX-1 were monitored using in-situ infrared (IR) and Raman spectroscopy. The tools proved valuable in understanding both the intermediate and product formation. The two tools are quite complementary Mettler Toledo s ReactIR (infrared) detects species in solution, while Raman will detect species in both solution and in solid form. 

In the infrared detection system, the sample is weighed into a special ceramic boat which is then placed into a combustion furnace at 1371°C (2500°F) in an oxygen atmosphere. Most of the sulfur present is converted to sulfur dioxide, which is then measured with an infrared detector after moisture and dust are removed by traps. The calibration factor is determined using standards approximating the material to be analyzed. 

ISO 15106-1 2003 Plastics - Film and sheeting - Determination of water vapour transmission rate - Part 1 Humidity detection sensor method ISO 15106-2 2003 Plastics - Film and sheeting - Determination of water vapour transmission rate - Part 2 Infrared detection sensor method ISO 15106-3 2003 Plastics - Film and sheeting - Determination of water vapour transmission rate - Part 3 Electrolytic detection sensor method... 

Bagley, K. A., Duin, E. C., Roseboom, W, Albracht, S. P. J. and Woodruff, W. H. (1995) Infrared-detectable group senses changes in charge density on the nickel center in hydrogenase from Chromatium vinosum. Biochemistry, 34, 5527-35. 

The available types of flame sensing detectors are ultraviolet (UV), infrared detection (IR), combination of these, and monitored closed circuit television (CCTV). These devices operate on the detection of certain wavelengths of light emitted by flames. They are used when there is a potential for fires that rapidly produce flame such as flash fire. 

Detectors for visible and ultraviolet radiation rely on incoming photons to eject electrons from a photosensitive surface or to promote electrons from the valence band of silicon to the conduction band. Infrared photons do not have sufficient energy to generate a signal in either kind of detector. Therefore, other kinds of devices are used for infrared detection. 

Figure 1. GPC infrared detection, recording, and data acquisition system...

The excellent performance of the instrumentation results from a combination of contributions from several components, i.e., the high sensitivity and stability of the infrared detection system, the data acquisition and computational procedures, and the stabilizer used. 

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