Spectral Response Designation

Spectral Response Numbers and Wavelength Regions of Maximum Response 

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The instruments used for color measurements are nowadays spectrophotometers determining the reflectance of a sample. Three-filter colorimeters, trying to mimic the spectral response of the human eye are now next to obsolete. For applications in the field of uni-pigments photometer illuminating/viewing geometries are standardized as methods A and B, and are designed to suit the individual application (see Section 1.4.2). For standards, see Table 1.1 ( Color Differences, Conditions/ Fvaluation... ). 

It is however possible to design specifically NP arrays with a strong polarization dependence in order to investigate polarization effects. This has recently been reported [21] using arrays of elongated gold NPs (with elliptic cross-section), which exhibit two distinct LSP resonances, each associated with a polarization along the two main axis of the ellipse. The spectral response for... 

A UV filter radiometer provides a convenient measure of the total UV output of a photon source, if properly designed for a specific source. They are broadband meters designed to measure incident radiation in the entire selected, UV region. An optical filter is used to limit the spectral responsivity to a certain band (e.g., UVB, near-UVA, or far-UVA). Ideally, the spectral responsivity is constant within the band and zero outside, but this is not the case in practice. Also, the characteristics of the filters may change with time and the device should be calibrated at least once per year. 

Figure 4.8. Schematic diagram showing basis of experiments designed to investigate energy transfer from a sensitizing molecule (S) to an acceptor molecule (A). The number of monolayers separating the two species governs the spectral response of the fluorescence spectrum, (a) The acceptor molecule does not absorb the UV radiation, (b) The separation distance is sufficiently small for the excitation energy of S to be transferred to A.

Comprehensive reviews (Kl, Ul) of the active sites of cholinesterase both postulated the presence not only of an esteratic site for butyrylcholinesterase but also of an anionic site. Additionally, in the region of the anionic site, there are two hydrophobic areas, one directly surrounding the anionic group and the second located at some distance from it (Kl). The presence of hydrophobic areas has been established (B32, C3, H29, H45, MIO) by the use of fluorescent probes with spectral responses which reflect the environment of the probe. Such probes can be used to monitor changes in the conformations of enzymes and can be designed to be active-site-directed, competitive inhibitors (H30). Aspects of the spectroscopy of intrinsic and extrinsic fluorescent probes have been reported (C3). 

Designing an imager for automotive applications necessitates balancing various factors. A high geometrical resolution (e.g., 4kx4k) can only be achieved by squeezing pixel pitch and in sequence the fill factor and sensitivity. The need for deep submicron CMOS processes shifts the maximum of the spectral response towards the blue end of the visual spectrum with small quantum efficiency. 

Another factor affecting the spectral response is the surface reflectivity of the photodiode protection film, which is made of materials including Si02. The refractive indexes for air, SiOz, and silicon are 1, about 1.45, and about 3.5, respectively. The differences in the refractive indexes result in the photodiode s spectral response being dependent on Si02 thickness. The photodiode including its protection film is therefore designed optimally to minimize the surface reflection effect. 

Unless one really needs the large cathode area of the end-on tubes (and for this problem lenses were created), we find that an excellent tube like the Hamamatsu 928 (Hamamatsu Corp., 420 South Ave., Middlesex, N.J. 08846) to be an extremely versatile performer. This PM has a very broad spectral response from 200 nm to 900 nm, exhibits little if any hysteresis, and can tolerate gross current overloads. A new development has been a miniature PM by Hamamatsu (R1635) that has a risetime of 800 psec. However, since it is an end-on design at present it has limited anode current capability and insufficient red response for many applications. 

A spectrum obtained for a sediment sample is rich in chemical information. However, the information is found in several overlapping combination bands and spectral overtones, rather than in distinct absorption peaks. The development of a reliable calibration model is therefore one of the most important steps to gain quantitative information on chemical compounds from the spectral response of a sample. This involves a thorough consideration of experimental design and multivariate calibration. 

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