Continuous radiation

Some X-ray photoelectron spectrometers are equipped with monochromators that can be used to remove unwanted radiation, such as the continuous radiation and even some of the weaker characteristic X-rays such as K<,3, K 4, Kas, and Ko,6, from the emission spectrum of the anode. A monochromator can also be used to resolve the K i,2 line into its two components K i and Ka2- Using a monochromator has at least two beneficial effects. It enables the narrow, intense K<, line to be used to excite spectra at very high resolution. A monochromator also prevents unnecessary radiation (continuous, K<,2, Ka3, K<,4, Kas, and Ka6) that might contribute to thermal or photochemical degradation from impinging on the sample. 

Brems-futter, n. brake lining, -leistung, /. brake horsepower, -atrahlen, f.pl. rays due to retarding of particles, -strahlung, /. radiation due to retarding of particles (usually continuous radiation). 

There is in addition to the pulse radiolysis technique the classical continuous radiation method. This later procedure uses either the 60Co-y sources or in the case of Pu the self a irradiation due to the radioactive decay. 

Cretaceous 138 Myr Gondwana begins to break up. Continued radiation of flowering plants mammals begin diversifying. Meteorite strikes Yucatan Peninsula at end of period causing mass extinction (ca. 75% of all species disappear)... 

High voltage hydrogen discharge lamps which give continuous radiation in the ultra-violet can be constructed quite simply and elaborate designs are unnecessary for many purposes. A very simple... 

Thermal radiation emitted by an object can be continuous, discontinuous or, in most cases, a mixture. A continuous radiation profile corresponds to an ideal black body, where only the temperature of the emitting object determines the emission profile. Discontinuous thermal emission spectra are caused by photons emitted during the relaxation of excited vibrational states. Since vibrational states are quantised, this results in emission bands at the wavelengths of the corresponding IR absorption bands. 

Table 32.19 (continued) Radiation Effects on Selected Terrestrial Plants... 

Consider continuous radiation with specific intensity I incident normally on a uniform slab with a source function 5 = Bv(Tex) unit volume per unit solid angle to the volume absorption coefficient Kp and is equal to the Planck function Bv of an excitation temperature Tcx obtained by force-fitting the ratio of upper to lower state atomic level populations to the Boltzmann formula, Eq. (3.4). For the interstellar medium at optical and UV wavelengths, effectively S = 0. 

If continuous radiation is incident on the atom, Eq. (A3.26) must now be summed over all frequencies lines are usually so narrow that Jv can be taken as constant for — oo < Aco < oo. F0.p2i 2 has to be expressed in terms of Jv. To do this, note that for unpolarized isotropic radiation... 

The first application of quantum theory to a problem in chemistry was to account for the emission spectrum of hydrogen and at the same time explain the stability of the nuclear atom, which seemed to require accelerated electrons in orbital motion. This planetary model is rendered unstable by continuous radiation of energy. The Bohr postulate that electronic angular momentum should be quantized in order to stabilize unique orbits solved both problems in principle. The Bohr condition requires that... 

For many of the analytical techniques discussed below, it is necessary to have a source of X-rays. There are three ways in which X-rays can be produced in an X-ray tube, by using a radioactive source, or by the use of synchrotron radiation (see Section 12.6). Radioactive sources consist of a radioactive element or compound which spontaneously produces X-rays of fixed energy, depending on the decay process characteristic of the radioactive material (see Section 10.3). Nuclear processes such as electron capture can result in X-ray (or y ray) emission. Thus many radioactive isotopes produce electromagnetic radiation in the X-ray region of the spectrum, for example 3He, 241Am, and 57Co. These sources tend to produce pure X-ray spectra (without the continuous radiation), but are of low intensity. They can be used as a source in portable X-ray devices, but can be hazardous to handle because they cannot be switched off. In contrast, synchrotron radiation provides an... 

In a laboratory generator, electrons are accelerated by a potential around 30 kV towards a solid target, where they are stopped by impact. The output contains the line spectmm superimposed upon a continuous spectrum. The line, or characteristic spectrum is characteristic of the element and is used in X-ray fluorescent analysis to identity the type and amount of an element present in a sample. The continuous radiation is also called the Bremsstrahlung, from the... 

Elkana et al. [138] made a careful study of the transfer of energy from excited naphthalene donor molecules to anthranilic acid acceptor molecules by observing the acceptor and donor fluorescence intensities when the donor was excited with continuous radiation (A = 272nm). The solvents were changed from glycerol to increasingly more and more... 

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