Infrared dual beam

Recently, the state-selective detection of reaction products tluough infrared absorption on vibrational transitions has been achieved and applied to the study of HF products from the F + H2 reaction by Nesbitt and co-workers (Chapman et al [7]). The relatively low sensitivity for direct absorption has been circumvented by the use of a multi-pass absorption arrangement with a narrow-band tunable infrared laser and dual beam differential detection of the incident and transmission beams on matched detectors. A particular advantage of probing the products tluough absorption is that the absolute concentration of the product molecules in a given vibration-rotation state can be detenuined. 

The most recent generation of NDIR analyzers have evolved to satisfy the frequently harsh industrial environments encountered. These analyzers utilize solid-state sensors for the detection of infrared radialion. Most frequently used sensors are lead selenide (PhSc). thermopiles, or pyroelectric detectors. The gas analyzers generally are configured as single-path instruments, dual-beam with a reference palh. or dual-channel with a reference filter. 

Fig. 6. Dual-beam infrared analyzer with j solid-state deteclor. (Inlnircd Industries. Inc)...

Dougherty TP, Heilweil EJ. Dual beam subpicosecond broadband infrared spectrometer. Optics Lett 1994 19 129-131. 

Infrared. The use of infrared for oil fingerprinting is well documented (32,33,34,35). The technique has a well-demonstrated capability and is one of the four primary Coast Guard methods (18) that is in operational use by COIL. In addition, it has been tested in the field for over a year in Philadelphia and will shortly begin testing in San Francisco, California, and New York, using relatively inexpensive dual-beam grating instruments. 

As shown in Figure 6, reactions were conducted in a closed vessel so that all CO2 could be captured and measured. Measurements of CO2 were used to calculate substrate conversion. The volume of this container was 38.2 L, which corresponds to approximately 1.5 moles of gas at ambient temperature and pressure. In early experiments, concentrations of CO2 were periodically determined by mass spectrometry of bomb samples. In more recent experiments, concentrations of CO2 were monitored continuously with a flow-through dual-beam infrared analyzer (Horiba PIR-2000R, path length of 15 mm), as shown in Figure 7. The absorption of light obeyed Beer s law, allowing determination of CO2 concentration. The analyzer provided... 

Perkin-Elmer Corporation markets the PE-21 dual beam infrared spectrometer... 

Abstract. A new infrared imaging polarimeter operating in dual-beam mode is described, together with some of the early results. 

Until the last twenty years, an infrared spectrometer meant a dispersive instrument this had a grating or prism to split light into its component frequencies, slits to provide the required resolution, and usually a dual sample beam to provide internal referencing of transmission. Today, Fourier transform infrared has almost completely replaced dispersive machines in the analytical laboratory. There are several reasons for this, which to be understood first require a brief introduction to the principles and technology involved. 

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