Reflection scattering

In the second broad class of spectroscopy, the electromagnetic radiation undergoes a change in amplitude, phase angle, polarization, or direction of propagation as a result of its refraction, reflection, scattering, diffraction, or dispersion by the sample. Several representative spectroscopic techniques are listed in Table 10.2. 

The amount of solar radiation that reaches any point on the ground is extremely variable. As it passes through the atmosphere, 25 to 50 percent of the incident energy is lost due to reflection, scattering nr absorption. Even on a cloud-free day about 30 percent is lost, and only 70 percent of 1,367 W/nf, or 960 W/m, is available at the earth s surface. One must also take into account the earth s rotation and the resultant day-night (diurnal) cycle. If the sun shines 50 percent of the time (twelve hours per day, every day) on a one square meter surface, that surface receives no more than (960 W/m ) X (12 hours/day) X (365 days/year) =... 

The use of nuclear techniques for the detection of buried expls (in mines) has been investigated by the US Army over the past 25 years. The basic approach is the use of a direct beam of highly penetrating radiation to irradiate the soil and the measurement of a reflected, scattered, induced or secondary signal to indicate the presence of a buried mine. A complete historical review and analysis of this work has been prepared by Coleman et al (Ref 18), A brief summary of the highlights of the overall effort is provided here... 

Whereas smokes are often characterized by the mode of their formation, any coned suspension of particles ranging from 0.01 to about 5.0 pm can be considered a smoke. These particles, when suspended in air, reflect, scatter and absorb radiation in a complex manner. A comprehensive model of these interactions in terms of visibility under various conditions was described recently (Ref 62)... 

Sun, W. X., and Shen, Z. X. 2003. Apertureless near-field scanning Raman microscopy using reflection scattering geometry. Ultmmicroscopy. 94 237 44. 

Concentrated light is sent through the container bottom. Looking from the other side of the container, the operator, looking from the side detects light reflections scattered by the particle against a dark background. 

Light impinging on a sample can be transmitted, refracted, reflected, scattered or absorbed. Beer Lambert s law, which is only related to the fraction absorbed, is applicable under the following conditions ... 

In granular solids or in analysis of liquids or slurries in which a considerable amount of particulate material exists, the scattering effect attenuates the optical signal in addition to the absorption. Scattering back from the body of the sample toward the surface produces the intensity to be measured as diffuse reflectance. Scattering also controls the depth of penetration of the sample as well as does its absorptivity (10). The complexity of these two factors acting at once is difficult to predict a priori. This is another reason why the empirical method and the empirical equation coefficients produced by a training set are essential. 

Optical biosensors typically consist of an optical fiber which is coated with the indicator chemistry for the material of interest at the distal tip (Fig. 22). The quantity or concentration is derived from the intensity of absorbed, reflected, scattered, or re-emitted electromagnetic radiation (e.g. fluorescence, bio- and chemiluminescence). Usually, enzymatic reactions are exploited, e.g. [463]. 

Internal transmittance refers to energy loss by absorption, whereas the total transmittance is that due to absorption, reflection, scatter, etc. 

The quantity minimized in least-squares refinement was 2I> (lol l d) where w = 4Fo /standard deviation and Fc and p being a pivot factor (laken as 0.03) used to decrease the weight of intense reflections. Scattering factors for neutral atoms correcied for anomalous scattering were used. The residuals were calculated as... 

In the extrinsic technique, light from a suitable source travels along the FO to the distal end where an immobilized sensing layer is located. Reflected, scattered or emitted light returns from the sample by a second fiber or by bifurcation of the original fiber. The emitted light is interpreted at the detector and is a measure of the concentration of the analyte of interest. The simplest FO biosensor uses absorbance measurements to determine any changes in... 

This equation is commonly referred to as the kinematic expression and is valid whenever the perturbation of the incident free space wavefunction by the scattering medium is sufficiently small. A highly reflective scattering event greatly perturbs the incident wavefunction and consequently the kinematic approximation is inadequate for such interactions. 

Polymers have many important optical properties, such as the refractive index, reflection, scattering, absorption, clarity, gloss, haze, birefringence, stress-optic coefficient, the yellowing induced by photochemical degradation, and the specific refractive index increment in dilute solutions. Its optical properties need to be considered in evaluating the potential usefulness of a polymer in many applications such as (but not limited to) compact disk coatings, automotive... 

Pharmaceutical vehicles (e.g., creams, gels, lotions, or solutions) can decrease the amount of light reflected, scattered, or absorbed in the skin1819 or increase the percutaneous absorption of drugs in the skin of humans and mice.20,21... 

Mirror to reflect scattered light into the detector... 

To summarize, rays are traced until the flux decreases below a specific cutoff value or the ray has undergone a specific number of internal or external reflections. Scattered rays carry six Stokes vectors and the six separate... 

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