Detectors lead sulfide

Infrared detectors -lead sulfide m [LEAD COMPOUNDS - LEAD SALTS] (Vol 15) -mercury compounds m [MERCURY COMPOUNDS] (Vol 16) -metal tellundes as [TELLURIUM AND TELLURIUM COMPOUNDS] (Vol 23)... 

Lead sulfide is used in photoconductive cells, infrared detectors, transistors, humidity sensors in rockets, catalysts for removing mercaptans from petroleum distillates, mirror coatings to limit reflectivity, high temperature solid-film lubricants, and in blue lead pigments (82). 

Detector elements are prepared either by sublimation in the presence of a small partial pressure of O2 or by chemical deposition from alkaline solution containing a lead salt and thiourea or selenourea (63). Lead sulfide and lead selenide deposit from solutions as mirror-like coatings made up of cubic crystallites 0.2—1 p.m on a side. The reaction may nominally be represented by the following ... 

Bruckman, G. 1933. Preparation and properties of thin lead sulfide films with special reference to their detector action. Kolloid-z 65 1-11. 

The first commercial unit was produced by Dickey-John. It contained a tungsten-halogen lamp, six interference filters, and uncooled lead sulfide (PbS) detectors, using a 0 45° geometry. That is, the light struck the sample straight on and the fight was collected at 45° to the normal. 

Instead of glowbars, as used in MIR, tungsten halogen lamps are the sources of light. The detectors are solid-state semiconductors such as lead sulfide (PbS) or indium gallium arsenide (InGaAs). These are orders of magnitude quieter than typical MIR detectors and often more sensitive. 

Lead sulfide occurs in nature as the mineral galena. Most lead comes from this ore. Additionally, lead sulfide has several industrial applications. It is used in infrared detectors transistors photoconductive cells high temperature lubricants and for glazing earthenware. It also is used as a catalyst in petroleum refining for removal of mercaptans from petroleum distillates. 

The NIR spectrometer used for method development and sample analysis was a Foss NIR Systems Model 6500 Forage Analyzer with a sample transport module and a standard reflectance detector array. The transport module moves the sample compartment up and down during data collection, thereby allowing a more representative spectrum to be obtained from bulky heterogeneous samples. The reflectance array uses two silicon detectors to monitor visible light from 400-850 nm and four lead-sulfide detectors to monitor NIR light from 850-2500 nm. Natural product sample compartment cells in 1/4-cup and 1-cup sizes were used as sample holders in the transport module. This instrument has a maximum resolution of 2 nm. 

Thermal and photoconductive detectors are used to measure radiation intensities, but all have relatively slow responses and are subject to drift. The lead sulfide or telluride photoconductive cell has a response time of about 0.5 ms, but sensitivity decreases sharply above 2900 cm" for the sulfide and above 1700 cm- for the telluride. Thermal detectors are employed at longer wavelengths. The simplest of these is the thermocouple, which has a relatively slow response (about 60 ms), and several are usually linked to form a thermopile. Bolometers... 

Quantum detectors are usually made of semiconductor materials or mixtures. Some commonly used quantum detectors are made of lead sulfide (PbS), lead selenide (PbSe), indium antimony (InSb), or mercury cadmium telluride (MCT, HgTe-CdTe). The absorption of infrared radiation in quantum detectors excites electrons... 

Lead sulfide (PbS) is a narrow band gap semiconductor used for many optical applications, like IR detectors [1], It is well known that semiconducting properties of PbS can be tailored by reducing the size of particles down to the nanometer scale. Semiconducting properties are greatly affected by the atomic structure. However, the atomic structure of nanoparticles may not be the same as the structure of the same substance in bulk. This paper focuses on study of the atomic structure of PbS nanoparticles. 

Near-IR light in the 1100- to 2500-nm range was transmitted through the concentrator onto the exterior arterial wall. The scattered light was detected at the proximal end of the CPC by lead sulfide detectors, located off axis of the incident beam. False color maps are then produced wherein the types and amounts of each type of plaque are determined. 

The temperature of solid specimens in the plasma was determined by means of an infrared radiation thermometer (Infrascope Model 3-1C00, Huggins Laboratories Inc., Sunnyvale, Calif.) attached to a chart recorder. This device employs a lead sulfide detector and suitable filters to permit remote measurement of 1.2 to 2.5/x radiation emitted by the specimen. Line filters and electrostatic shielding were employed to minimize interaction of the radiofrequency field with the infrared thermometer. To compensate for variations in emissivity and inhomogeneity in the optical field, empirical calibration curves were constructed based on measurements of new and partially oxidized graphite pellets in a con-... 

This type of detector is constituted, for the mid-IR region, of a ternary alloy of mercury-cadmium telluride (MCT) or indium antimonide (InSb) deposited upon an inert support and for the near-IR of lead sulfide (PbS) or an other ternary alloy of indium/gallium/arsenic (InGaAs). Sensitivity is improved when these detectors are cooled down to liquid nitrogen temperature of (77 K). 

Photon detectors consist of a thin film of semiconductor material, such as lead sulfide, lead telluride, indium antimonide, or germanium doped with copper or mercury, deposited on a nonconducting glass and sealed into an evacuated envelope. Photon flux impinging on the semiconductor increases its conductivity. Lead-sulfide detectors are sensitive to radiation below about 3 fj.m in wavelength and have a response time of about 10 /nsec. Doped germanium detectors cooled to liquid-helium temperatures are sensitive to radiation up to about 120 jitm in wavelength, and have a response time of approximately 1 nsec. 

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