Infrared photometers

Infrared photometers Paramagnetic oxygen sensors Thermal conductivity sensors Distillation-type analyzers 1 930s and 1 940s Refining... 

Infrared photometers designed to monitor the concentration of air pollutants, such as carbon monoxide, nitrobenzene, vinyl chloride, hydrogen cyanide, and pyridine, are often used to ensure compliance with regulations established by the Occupational Safety and Health Administration (OSHA). Interference filters, each designed for the determination of a specific pollutant, are available. These transmit narrow bands of radiation in the range of 3 to 14 p,m. 

IR spectra were obtained using a Perkin-Elmer Infrared photometer. Model 297. Sampling method is reported for individual cases absorptions are reported in cnT, and the intensity is designated as s (strong), m (medium), w (weak), or b (broad),... 

Flame infrared emission (FIRE) spectrometry is a new technique that is useful in determining FAC in liquid bleach. In the FIRE method, solutions of sodium hypochlorite are acidified to produce aqueous CI2 (reactions [I] and [II] and Figure 1). Dissolved CI2 is liberated from solution in a purge tube and converted to vibrationally excited HCl molecules in a hydrogen-air flame. The intensity of the P-branch of the HCl stretching vibration at 3.8 pm is monitored with a simple filter infrared photometer that employs a lead selenide detector. 

The definition team for the infrared photometer consists of R. Hall, D. Kleinmann and G. Neugebauer. As a first generation experiment the team proposes a simple filter wheel photometer which works from 1 p to 1 mm. A spectrometer with a spectral resolution of 3 x 10 is proposed for a second generation... 

In summary, at shorter wavelengths the main utility of the infrared photometer will be in the high spatial resolution of the (L)ST while at longer wavelengths the (L)ST will provide unequalled sensitivity as well. The infrared capability extends the wavelength coverage of the (L)ST by a factor of a thousand and truly belongs as one of the instruments in the spacecraft observatory. 

Instrument Designs for Infrared Absorption The simplest instrument for IR absorption spectroscopy is a filter photometer similar to that shown in Figure 10.24 for UV/Vis absorption. These instruments have the advantage of portability and typically are used as dedicated analyzers for gases such as ITCN and CO. 

Fig. 11. Modification18 of Sofica photometer for use at 0 = 1060 nm pd - monitoring photodiode, bs — beam splitter, i - iris, pm — photomultiplier, ire — infrared converter, ps - power supplies, cro - cathode ray oscilloscope, a - aperture, p — reflecting prism, c — cell...

Infrared (IR) spectroscopy offers many unique advantages for measurements within an industrial environment, whether they are for environmental or for production-based applications. Historically, the technique has been used for a broad range of applications ranging from the composition of gas and/or liquid mixtures to the analysis of trace components for gas purity or environmental analysis. The instrumentation used ranges in complexity from simple filter-based photometers to optomechanically complicated devices, such as Fourier transform infrared (FTIR) spectrometers. Simple nondispersive infrared (NDIR) insttuments are in common use for measurements that feature well-defined methods of analysis, such as the analysis of combustion gases for carbon oxides and hydrocarbons. For more complex measurements it is normally necessary to obtain a greater amount of spectral information, and so either Ml-spectrum or multiple wavelength analyzers are required. 

Sample detection in polymer HPLC is a large problem. Only few polymers bear chromophores that allow direct application of photometers, typical for HPLC of many low-molar-mass substances. The use of detectors that operate in the infrared region of spectrum is complicated by the absorptivity of eluents. Still, there is observed some revival in this area, especially in the SEC of polyolefins. 

On-line size exclusion chromatographic (SEC) analyses were performed with a Waters Model 401 differential refractometer (DR), a Waters Model 480 ultraviolet (UV) variable wavelength spectrophotometer and a Foxboro Miran lA infrared (IR) photometer, equipped with a zinc selenide ultramicro flowcell of 1.5 mm nominal pathlength and 4.5 /xl volume, purchased from the same supplier. A set of ten Mycrostyra-gel (Waters Associates) columns, regenerated by Analytical Sciences Inc. (ASI) and of nominal porosities 100, 500 (two) 10 (two), 10 (three), 10 and lO X, in the order given and a mobile phase flow rate of 1 ml/min was used. The column set had a specific resolution of 19.7 in 1,4-dioxane, as determined by the method of Yau(2). 

Cadmium sulfide is often used in the photometers of cameras to measure the avaflnWe visible light. Suppose you were interested in infrared photography. Using Fig. 7.2S. aiggest some compounds that might be suitable for an infrared photocell. 

By definition, photometers do not respond to radiation in the infrared or the ultraviolet (Fig. 4-4a). They are light meters in the sense that they mimic human vision that is, they respond to photons in the visible region, similar to the light meter on a camera. A candle is a unit of luminous intensity, originally based on a standard candle or lamp. The current international unit is called a candela (sometimes still referred to as a candle ), which was previously defined as the total light intensity of 1.67 mm2 of a blackbody radiator (one that radiates maximally) at the melting temperature of pure platinum (2042 K). In 1979 the candela was redefined as the luminous intensity of a monochromatic source with a frequency of 5.40 x 1014 cycles s-1 (A, of 555 nm) emitting 0.01840 Js-1 or 0.01840 W (1.464 mW steradian-1, where W is the abbreviation for watt and steradian... 

Three types of infrared instruments are found in modem laboratories dispersive spectrometers (or spectrophotometers), Fourier-transform (FTIR) spectrometers, and fdter photometers. The first two are used for obtaining complete spectra for quali-... 

All the component parts used in photometers have the same working principle as those already described in other spectrometers, for example, the infrared spectrometer. The prism and refraction grids are used as monochromators. The detector is usually made of different types of photoresistors depending on the instrument type. 

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