Radiation bands

Bands initially present in unirradiated PE Bands induced due to y radiation Bands induced due to reactor radiation Literature Intensity change on y radiation Low y dose Middle y dose Highy dose... 

The spectrum of the red luminescence has a complex stmcture. We were able to separate three components of red luminescence that each have their own kinetics and that differ by the character of excitation. The radiation band at 7300-7800 A is predominantly excited by light with A,i = 3700-4800 A and has a three - exponential time dependence of afterglow with time constants of 3 msec, 15 msec, and 75 msec. The relatively strong emission line at 7175 A has maxima in the excitation spectrum at 3700 and 5200 A. It is characterized by an afterglow time constant of x = 33 psec. Several narrow lines in the 6900-7200 A region are well excited with A,=4000-4800 A and are characterized by Xi = 3 and %2 = 22 msec. 

Colors and impurities obviously filter out certain radiation bands. Increasing the thickness of a container will obviously increase the absorption of any given absorbed band. One of the most difficult items to measure is the effect of the container geometry on the exposure. Depending on the physical shape of the container and the angle(s) of incidence of the radiation (cosine law effect), radiation can be reflected or refracted by flat surfaces and possibly focused internally by rounded corners. 

Here /g is the intensity of incident monochromatic radiation, I is the intensity of radiation at a distance I cm, and e is the decadic molar extinction coefficient of an absorbing species (concentration, c mole. 1 ). This law is strictly valid only if molecular interactions are unimportant at all concentrations. Deviations occur for a variety of reasons this means that the validity of the law should be checked under the particular experimental conditions. An initial determination of the absorption spectrum of the compound under investigation is obligatory. This produces immediate qualitative information, particularly about the usefulness of the source of radiation. Banded, diffuse or continuous spectra give direct information about the complexity and variety of primary processes that may occur. Further information will be gained from the effect of radical traps such as Oj or NO, and of various energy transfer agents. 

The same system was used to record temporal data from a H2/air flame using spectral band-pass filters. Fig. 6 shows water flame spectra obtained under two different flame conditions a near stoichiometric flame and a lean flame. The spectral data match the known theoretical spectra of water. The width of the spectral band is an indicator of water temperature. Thus, we can determine the density and temperature of the water vapor within the flame using a set of three spectral bands corresponding to the center and wing of the water band, and a null band outside of the water radiation band. 

This underlines the fact that the biological effects of UV radiation may well be used for medical purposes, in spite of their detrimental side effects. These side effects drive continuing efforts to perform therapeutic efforts involving less, or sharper defined, UV radiation at minimal dosage or the use of less harmful radiation bands, such as visible light. 

In addition to the line spectra produced by electric arc or spark, band spectra are produced as well as continuous background radiation. Band spectra come from the molecular species in the vapor state that is produced from the spark. The molecular energy levels are superimposed over the electronic energy levels. Typically, cyanogens (CN), siloxanes (SiO), and hydroxyl radicals are sources of band spectra. Continuous background spectra are produced from the arc and spark source itself. The heating of the electrodes will produce radiation that is temperature dependent and approximates that of a black body [1],... 

Infrared spectra (i.r.) Infrared spectra of the materials II and III were obtained with a BROKER IFS48 FT-IR spectrometer purged with nitrogen gas and using a mid band mercury cadmium telluride (MCI) detector. A HARRICK Praying Mantis diffuse reflectance attachment with two ellipsoidal mirrors collected the diffuse reflectance spectra. To avoid residual radiation bands all samples were diluted with KBr powder (Uvasol quality, E. Merck) so that the sample concentration was about 10 %. 

Andrady [122] reported an activation spectrum for yellowing of expanded, extruded polystyrene sheets, exposed to filtered xenon-source radiation, using the cut-on filter technique. Yellowness Index as well as the L, a, b color parameters were determined. The activation spectrum for yellowing shown in Fig. 12 shows the most effective radiation band in the source spectrum to be X = 310-345 nm. 

In figure 2.12, the whole area under each curve represents black body radiation from solid surfaces (per Planck s Law). Two shaded bars show the narrow radiating bands for carbon dioxide gas. Similar but shorter bands for the other common triatomic gas, H2O, are shown in figures 2.17 and 2.18. 

The work used samples obtained by means of casting polymerization in the shape of disks with diameter 20-40 mm and thickness mm Fixation of samples under study was affected by radiation of mercury lamp at 436 nm or that of "blue" LED with maximum of radiation band at 470 nm. Schematic diagram of information recording in such medium is shown on Fig. 7b by the example of constructing a hologram-grating. 

Direct, in situ HPTLC-FTIR measurement is carried out by diffuse reflectance using a DRIFT (Diffuse Reflection Infrared Fourier Transform Spectroscopy) unit (Fig. 15) (40-45). It is necessary to take account of the fact that at wavelengths where the absorption is large and the refractive index is high, the incident radiation is almost 100% normally reflected at the surface so that there is scarcely any diffuse reflection, which is that part of the reflection that contains the spectral information concerning the sample, in contrast to the normal (Fresnel) reflection. This means that reflectance minima and not the expected reflectance maxima are obtained at wavelengths of strong absorption. With silica gel, the absorption maxima, also known as residual radiation bands, dominate appreciably in the 1300-... 

While both conductive and convective transfers involve the flow of energy through a solid or fluid substance, no medium is required to achieve radiative heat transfer. As a matter of fact, electromagnetic radiation travels more efficiently through a vacuum. The thermal radiation band is shown within the electromagnetic spectrum in Figure 6.7. 

Notwithstanding the complexity of experiments under natural radiation, various spectral studies have been performed by removing increasingly larger portions of the solar UV spectrum by means of different combinations of long-pass filters, or by supplementing UV radiation by means of appropriate fluorescent lamps. Recently, a sophisticated irradiation s) tem was described, which uses filters and supplementary UV lamps and can provide computer-controlled modulated changes in any radiation band between about 250 and 730 nm. ... 

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