Radiation reflection

For opaque materials, the reflectance p is the complement of the absorptance. The directional distribution of the reflected radiation depends on the material, its degree of roughness or grain size, and, if a metal, its state of oxidation. Polished surfaces of homogeneous materials reflect speciilarly. In contrast, the intensity of the radiation reflected from a perfectly diffuse, or Lambert, surface is independent of direction. The directional distribution of reflectance of many oxidized metals, refractoiy materials, and natural products approximates that of a perfectly diffuse reflector. A better model, adequate for many calculational purposes, is achieved by assuming that the total reflectance p is the sum of diffuse and specular components p i and p. ... 

Clouds of Nonblack Particles The correction for nonblackness of the particles is complicated by multiple scatter of the radiation reflected by each particle. The emissivity . of a cloud of gray particles of individual surface emissivity 1 can be estimated by the use of Eq. (5-151), with its exponent multiplied by 1, if the optical thickness alv)L does not exceed about 2. Modified Eq. (5-151) would predict an approach of . to 1 as L 0°, an impossibihty in a scattering system the asymptotic value of . can be read from Fig. 5-14 as /, with albedo (0 given by particle-surface refleclance 1 — 1. Particles with a perimeter lying between 0.5 and 5 times the wavelength of interest can be handledwith difficulty by use of the Mie equations (see Hottel and Sarofim, op. cit., chaps. 12 and 13). 

The portion of the incoming radiation reflected and scattered back to space is the albedo. The albedo of clouds, snow, and ice-covered surfaces... 

Percent of Incident Radiation Reflected by a Water Surface (Albedo of Water)"... 

When infrared radiation with electric field amplitude Eo impinges on the film-covered substrate, some is reflected from the ambient/film interface while some is transmitted into the film and then reflected at the film/substrate interface. Some of the radiation reflected at the film/substrate interface is reflected back into the film at the film/ambient interface. However, some is transmitted into the ambient (see Fig. 4). The reflection coefficient (r) for the film/substrate system is calculated by summing the electric field amplitudes for all of the waves reflected into the ambient and then dividing by the electric field amplitude Eo) of the incident radiation. 

The value of a0 = 5.370 0.005 A (table I) was obtained from a photograph of radiation reflected on the same plate from (100) of sulvanite and (0001) of /3-alumina, for which a spacing of 11.225 A was assumed1). This agrees well with the value X 10.750 = 5.375 A from de Jong. 

Fig. 17-1 The global climate system, (a) Energy fluxes, including incoming solar radiation, reflected radiation, emitted longwave radiation (from an effective altitude of ca. 6 km), and atmospheric and oceanic heat flux toward the polar regions, (b) The atmospheric circulation corresponding to part (a). Refer back to Fig. 7-4 and associated text for a discussion of the general circulation.

This interaction leads to at least four (4) components, namely R- the radiation reflected, A- the radiation absoit>ed, T- the radiation transmitted, and S - the radiation scattered. A depiction of these interactions is given in the following diagram ... 

The formal definition of this quality factor, Q, is the amount of power stored in the resonator divided by the amount of power dissipated per cycle (at 9.5 GHz a cycle time is l/(9.5 x 109) 100 picoseconds). The dissipation of power is through the resonator walls as heat, in the sample as heat, and as radiation reflected out of the resonator towards the detector. The cycle time is used in the definition because the unit time of one second would be far too long for practical purposes within one second after the microwave source has been shut off, all stored power has long been dissipated away completely. 

Albedo The amount of radiation reflected from a surface across all wavelengths. 

To study the ultraviolet or visible absorption spectroscopy of a solid material, the radiation reflected from the surface of the sample is detected and recorded as a function of the incident wavelength. The fraction of light reflected from a sample surface is given by... 

In some techniques, including XRD, some IR spectroscopic techniques, and neutron activation, the surface of the soil sample is analyzed using radiation reflected or emitted from the sample. In the other types of spectroscopy, such as NMR, information is obtained from radiation passing through the sample. Infrared spectroscopy (both NIR and MIR) can be used in both transmission and reflection analyses. 

The laser interferometer consists of two coupled resonators, one containing the laser, the other the plasma under investigation (Fig. 10). The laser radiation, reflected back from mirror A/s, which contains phase information about the refractive index of the plasma, interferes with the laser wave in cavity A, resulting in an amplitude modulation of the laser output 267). This modulation can be related to the refractive index and therefore to the plasma frequency and electron density. With a curved rather than a planar mirror, the sensitivity can be increased by utilizing transverse cavity modes 268). 

Attenuated total reflectance infrared (ATR-IR) is used to study films, coatings, threads, powders, interfaces, and solutions. (It also serves as the basis for much of the communication systems based on fiber optics.) ATR occurs when radiation enters from a more-dense material (i.e., a material with a higher refractive index) into a material that is less dense (i.e., with a lower refractive index). The fraction of the incident radiation reflected increases when the angle of incidence increases. The incident radiation is reflected at the interface when the angle of incidence is greater than the critical angle. The radiation penetrates a short depth into the interface before complete reflection occurs. This penetration is called the evanescent wave. Its intensity is reduced by the sample which absorbs. 

Incoming radiation from the Sun and backradiation emitted by Earth interacts with the atmosphere. Although about half of the Sun s radiation passes directly to Earth s surface, a portion is reflected back directly into space, while another portion is absorbed by atmospheric gases and reradiated. Figure 18.3 shows the fate of radiation intercepting Earth. About half of the incoming solar radiation actually reaches the surface of Earth. The rest is reflected or absorbed by the atmosphere or clouds. Infiared radiation reflected from Earth s surface is partially absorbed and reflected by the atmosphere and clouds. Some of this radiation is reradiated back toward Earth s... 

These sources are direction radiation from the sun, radiation scattered by gases and particles, and radiation reflected from the earth s surface. 

Poulter (Ref 12) observed effects similar to those of Ref 11 and concluded that the action of foil was not due to confinement since the foil was too thin to provide such Confinement. He suggested rather that the propagation of deton was assisted by radiation, reflected from the inside surface of the foil, which otherwise would be lost (See also Ref 13, p 202)... 

Chemical State Radiation Reflection or Diffraction Infrared attenuated total reflectance (ATR) Infrared reflectance Ultraviolet spectroscopy X-ray diffraction Resonant Response NMR EPR... 

B. Dimensional Stability Boroscope Miniaturized T.V. Microscope Radiation Reflectance or Diffraction Photocell (visible) X-ray diffraction U.V. reflectance spectroscope y-Ray back-scatter Scintillation read out Infrared reflectance Radiation emission Infrared scan Profilometer... 

Diffuse reflectance R is a function of the ratio K/S and proportional to the addition of the absorbing species in the reflecting sample medium. In NIR practice, absolute reflectance R is replaced by the ratio of the intensity of radiation reflected from the sample and the intensity of that reflected from a reference material, that is, a ceramic disk. Thus, R depends on the analyte concentration. The assumption that the diffuse reflectance of an incident beam of radiation is directly proportional to the quantity of absorbing species interacting with the incident beam is based on these relationships. Like Beer s law, the Kubelka-Munk equation is limited to weak absorptions, such as those observed in the NIR range. However, in practice there is no need to assume a linear relationship between NIRS data and the constituent concentration, as data transformations or pretreatments are used to linearize the reflectance data. The most used linear transforms include log HR and Kubelka-Munk as mathemati-... 

Krasnopol skiy, V.A. (1966) The ultraviolet spectrum of solar radiation reflected by the terrestrial atmosphere and its use in determining the total content and vertical distribution of atmospheric ozone. Russian Geomagnetism andAeronomy 6 236-242. 

Fourier transform (FT) IR spectroscopy is one of several nondispersive optical spectroscopies based on interferometry. A two-beam interferometer first proposed by Michelson is the basis of most modern FT-IR spectrometers, as exemplified by the schematic of the Bruker Equinox 55 spectrometer (Bruker Optik, Ettlingen, Germany) in Fig. 2. Simply described, the interferometer comprises a beam splitter and two mirrors. A collimated beam of IR energy is split at the beam splitter into equal halves. Half of the energy travels through the beam splitter to one of the mirrors, which is positioned at a fixed distance away from the beam splitter. The reflected beam travels perpendicular to the incident beam to a moving mirror. IR radiation reflects off the fixed and moving mirrors and recombines at the beam splitter. The recombined IR beam projects from the interferometer towards the detector on an optical path perpendicular to the source beam. 

ADEOS An improved, satellite Earth-observing system equipped with modernized radiometer of the visible and near-IR intervals (AYNIR), ocean color and temperature scanner (OCTS), and radiometer POLDER to carry out global systematic measurements of polarization and spectral characteristics of solar radiation reflected by the Earth-atmosphere system. The satellite ADEOS-2/ Midori-2 was launched on December 14, 2002 by the Japan Space Agency and is an ideal means of global monitoring. 

Estimates of albedo changes from data on the outgoing shortwave radiation reflected by the Moon (2000-2004) + 16... 

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