Charge coupled devices infrared sensitive

Because charge-coupled devices are sensitive to infrared light, they can be used in some solid-state night-vision devices—and some commercial cameras and video cameras have night-vision capability. 

A photomultiplier tube is a sensitive detector of visible and ultraviolet radiation photons cause electrons to be ejected from a metallic cathode. The signal is amplified at each successive dynode on which the photoelectrons impinge. Photodiode arrays and charge coupled devices are solid-state detectors in which photons create electrons and holes in semiconductor materials. Coupled to a polychromator, these devices can record all wavelengths of a spectrum simultaneously, with resolution limited by the number and spacing of detector elements. Common infrared detectors include thermocouples, ferroelectric materials, and photoconductive and photovoltaic devices. 

Major technological and scientific innovation in the past 10 to 15 years has significantly broadened the applicability of Raman spectroscopy, particularly in chemical analysis. Fourier transform (FT)-Raman, charge-coupled device (CCD) detectors, compact spectrographs, effective laser rejection filters, near-infrared lasers, and small computers have contributed to a revolution in Raman instrumentation and made routine analytical applications possible. An increase in instrumental sensitivity by factors as large as 10, plus decreases in both interferences and noise resulted from this revolution. The number of vendors of Raman spectrometers increased from 3 to 12 over a 10-year period, and integrated commercial spectrometers led to turnkey operation and robust reliability. 

The Raman effect is due to the same vibrations that give rise to the infrared spectrum. Raman scattering describes the inelastic scattering of incident light by certain vibrational transitions (described as Raman active). Note that this is not a fluorescence effect. The molecule is not electronically excited and the incident photon interacts with the vibration of the molecule on a time-scale of the order of 10 seconds. The Raman effect is also weak—except for resonant transitions, no more than one photon in a million is inelastically scattered in this way. Hence the need for powerful sources of monochromatic radiation (lasers) and sensitive detectors (photo-multiplier tubes or charge-coupled devices). 

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