Spectral transmissivity

Figure 5.8 Transmission spectral characteristics of a colour filter.

A major use for photomultiplieis has been in (he scintillation counter wherein combination with a fluorescent material, it is used to detect nuclear radiation. They also have been used ill star and planet tracking for guidance systems as well as in star photometry and quantitative measurements of soft x-rays in outer space. Additional uses include facsimile transmission, spectral analysis, process control, and wherever extremely low-liglit levels must be detected. For applications in photometers, see also Photometers. 

The method utiHzes the angular dependence of the dielectric filter on impacting photon direction, with its transmission spectral profile shifting to the blue, in fine with the increase in the deviation of photons away from normal incidence. This feature enables the filter to serve as a unidirectional mirror, passing a semi-colhmated laser beam through unhindered from one side while at the other side reflecting any photons emerging from the sample predominantly at random directions, back into the sample. 

The photoelectron spectrum of 1,3,5-triazine has been recorded <84JA2805>. The assignments remain unchanged from those previously reported <72HCA255>. Investigation of the vapors over heated 1,3,5-triphenylhexahydro-1,3,5-triazine, by UV photoelectron and electron transmission spectral techniques, found them to consist mainly of monomeric A-methyleneaniline <85JCS(P2)1623>. 

The potential importance of diamond in technology follows from the wide range of technically desirable thermomechanical, optical, and electronic properties exhibited by diamond [9-13]. In addition to its extreme hardness and exceptional wear resistance, diamond is the stiffest known material, has a broad transmission spectral range (from the ultraviolet to the far infrared and extending to microwave frequencies), has the highest room-temperature thermal conductivity, one of the lowest thermal expansion coefficients and is radiation hard and chemically inert to all acid and base reagents. 

The transmission spectral sensitivity is defined similarly to the case of reflection (1.5.4°) ... 

McCall, S. H. C. P., Pierre, J. E., Mabee, A., Tennyson, R., Morison, D., Kleiman, J., Iskanderova, Z., and Gudimenko, J. (1994). The Atomic Oxygen Exposure Effects Module of the Database for the Properties of Black, White, Reflective and Transmissive Spectrally Selective Surfaces, SPIE Proceedings, Vol. 2260. Presented at the SPIE Conference, Stray Radiation in Optical Systems II, July 24-29, San Diego. 

Conversion of transmittance spectra to absorbance units. This step was required since the PE400 stores spectra in the mapping file as raw transmission spectral vectors. The spectral vector corresponding to a given 6.25 pm X 6.25 pm pixel will be henceforth referred to as pixel spectrum. 

The aim of the experiment was to study the transmission of a signal through the weld and to measure the frequency and phase dependencies of parameters of acoustic signals from the angle of incidence and beam path within the weld volume. One of the shift of the spectral characteristics the signal is shown in Figure 4(a,b). 

The common civil engineering seismic testing techniques work on the principles of ultrasonic through transmission (UPV), transient stress wave propagation and reflection (Impact Echo), Ultrasonic Pulse Echo (UPE) and Spectral Analysis of Surface Waves (SASW). 

Transmission Fourier Transform Infrared Spectroscopy. The most straightforward method for the acquisition of in spectra of surface layers is standard transmission spectroscopy (35,36). This approach can only be used for samples which are partially in transparent or which can be diluted with an in transparent medium such as KBr and pressed into a transmissive pellet. The extent to which the in spectral region (typically ca 600 4000 cm ) is available for study depends on the in absorption characteristics of the soHd support material. Transmission ftir spectroscopy is most often used to study surface species on metal oxides. These soHds leave reasonably large spectral windows within which the spectral behavior of the surface species can be viewed. 

Transmission. The spectral transmission of glass is determiaed by reflectioa at the glass surfaces and the optical absorption within the glass. Overall transmission of a flat sample at a particular wavelength is equal to (1 — R), where P is the absorption coefficient, t the thickness of glass, and... 

The emissivity, S, is the ratio of the radiant emittance of a body to that of a blackbody at the same temperature. Kirchhoff s law requires that a = e for aH bodies at thermal equHibrium. For a blackbody, a = e = 1. Near room temperature, most clean metals have emissivities below 0.1, and most nonmetals have emissivities above 0.9. This description is of the spectraHy integrated (or total) absorptivity, reflectivity, transmissivity, and emissivity. These terms can also be defined as spectral properties, functions of wavelength or wavenumber, and the relations hold for the spectral properties as weH (71,74—76). 

Optical Properties. The optical transmission of vitreous siUca is influenced by impurities and the forming process. Ultrapure vitreous siUca has the abihty to transmit from the deep ultraviolet, through the visible, and into the near-infrared spectral range. 

Pure carbon disulfide is a clear, colorless Hquid with a deHcate etherHke odor. A faint yellow color slowly develops upon exposure to sunlight. Low-grade commercial carbon disulfide may display some color and may have a strong, foul odor because of sulfurous impurities. Carbon disulfide is slightly miscible with water, but it is a good solvent for many organic compounds. Thermodynamic constants (1), vapor pressure (1,2), spectral transmission (3,4), and other properties (1,2,5—7) of carbon disulfide have been deterrnined. Principal properties are Hsted in Table 1. 

An important effect of air pollution on the atmosphere is change in spectral transmission. The spectral regions of greatest concern are the ultraviolet and the visible. Changes in ultraviolet radiation have demonstrable adverse effects e.g., a decrease in the stratospheric ozone layer permits harmful UV radiation to penetrate to the surface of the earth. Excessive exposure to UV radiation results in increases in skin cancer and cataracts. The worldwide effort to reduce the release of stratospheric ozone-depleting chemicals such as chlorofluorocarbons is directed toward reducing this increased risk of skin cancer and cataracts for future generations. 

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