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THERMODYNAMICS OF RADIATION

Electromagnetic radiation which interacts with matter also reaches a state of thermal equilibrium with a definite temperature. This state of electromagnetic radiation is called thermal radiation, also called heat radiation in earlier literature. In fact, today we know that our universe is filled with thermal radiation at a temperature of about 2.8 K. [Pg.283]

It has long been observed that heat can pass from one body to another in the form of radiation with no material contact between the two bodies. This was called heat radiation. When it was discovered that motion of charges produced electromagnetic radiation, the idea that heat radiation was a form of electromagnetic radiation was taken up, especially in the works of Gustav Kirchhoff (1824-1887), Ludwig Boltzmann (1844-1906), Josef Stefan (1835-1893) and Wilhelm Wien (1864-1928) and its thermodynamic consequences were investigated [1]. [Pg.283]


In the present state of science, it seems hardly possible to frame a dynamic theory of molecular action which shall embrace the phenomena of thermodynamics, of radiation, and of the electrical manifestations which accompany the union of atoms. .. Even if we confine our attention to phenomena distinctively thermodynamic, we do not escape difficulties in as simple a matter as the number of degrees of freedom of a diatomic gas. .. Certainly, one is building on an insecure foundation, who rests his work on hypotheses concerning the constitution of matter. [Pg.440]

S.2 General considerations on the thermodynamics of radiation-induced depolymerization... [Pg.389]

In the following pages I have endeavoured to deduce the principles of Thermodynamics in the simplest possible manner from the two fundamental laws, and to illustrate their applicability by means of a selection of examples. In making the latter, I have had in view more especially the requirements of students of Physical Chemistry, t6 whom the work is addressed. For this reason chemical problems receive the main consideration, and other branches are either treated briefly, or (as in the case of the technical application to steam and internal combustion engines, the theories of radiation, elasticity, etc.) are not included at all. [Pg.561]

The most common states of a pure substance are solid, liquid, or gas (vapor), state property See state function. state symbol A symbol (abbreviation) denoting the state of a species. Examples s (solid) I (liquid) g (gas) aq (aqueous solution), statistical entropy The entropy calculated from statistical thermodynamics S = k In W. statistical thermodynamics The interpretation of the laws of thermodynamics in terms of the behavior of large numbers of atoms and molecules, steady-state approximation The assumption that the net rate of formation of reaction intermediates is 0. Stefan-Boltzmann law The total intensity of radiation emitted by a heated black body is proportional to the fourth power of the absolute temperature, stereoisomers Isomers in which atoms have the same partners arranged differently in space, stereoregular polymer A polymer in which each unit or pair of repeating units has the same relative orientation, steric factor (P) An empirical factor that takes into account the steric requirement of a reaction, steric requirement A constraint on an elementary reaction in which the successful collision of two molecules depends on their relative orientation. [Pg.967]

Max Planck (1858-1947 Nobel Prize for physics 1918) at first did not have the atom in his sights. He was more interested in thermodynamics, and especially in the laws of radiation. In 1900 he surprised the Physical Society of Berlin — and later the whole world — with an experimentally based realization that changed the world view. In contrast to time and space, energy is guantized. Thus it does not form a continuum, but is essentially "grainy". The smallest unit is the Planck constant, a fundamental natural constant. [Pg.24]

The solid state polymerisation of diacetylenes (2) with U.V. radiation, heating or shear force is most indicative of the predominant influence of electron-lattice coupling. The details of the chemical changes that occur during th polymerisation process are crucial (2,40) but the overall description only needs part of this chemical information. The kinetics and thermodynamics of the polymerisation process using an elastic strain approach have been worked out in (41). [Pg.181]

A third approach within the newly defined physical chemistry was to prove crucial to dealing with the old problems of affinity and reaction mechanisms. Like thermodynamics and radiation theory, it promised and eventually delivered a conceptual framework that constituted a truly theoretical chemistry. At the same time, this new ionic and electronic approach to chemical explanation served as an important testing ground for theoretical physicists primarily concerned with the physics tradition of ether- and electrodynamics. Helmholtz,... [Pg.147]

Difficulties develop if the thermometer is exposed to certain types of radiation. However, calculations indicate that under normal circumstances, these radiation fields raise the temperature by only about 10 °C, which is a quantity that is not detectable even with the most sensitive current-day instruments [4]. Similarly, we shall neglect relativistic corrections that develop at high velocities, for we do not encounter such situations in ordinary thermodynamic problems. [Pg.33]

The importance of chemistry to the nuclear power industry is now well recognized. Chemical control in water circuits is an accepted part of the operating requirements of nuclear generating stations, as it is for modern fossil-fired stations. While there have been major advances in knowledge of the chemistry of aqueous systems at temperatures above lOQoC, there is still a need for further work. As we improve our understanding of thermodynamics and kinetics of solid-aqueous reactions and the effect of radiation on them, we can expect further advances in controlling radiation fields in reactor circuits and in minimizing iron deposition in GS plants. [Pg.328]

Miodownik et al. 1979, Watkin 1979). Irradiation can cause void-swelling, suppression of a formation in stainless steels and non-equilibrium precipitation of silicides. These phenomena are complex and occur by a combination of thermodynamic and kinetic effects. However, it was shown by Miodownik et al. (1979) that a thermodynamic analysis could be used to good effect to rationalise the effect of radiation on silicide formation. Although the work was done for a simple alloy system, it demonstrates how thermodynamics can be used in unusual cirounstances. [Pg.417]

Johnson R. A thermodynamic method for investigation of radiation-induced changes in the microcirculation of human tumors. Int J Radiat Oncol Biol Phys 1976 1 659-670. [Pg.375]

To evaluate the thermodynamic and radiation properties of a natural or perturbed state of the upper atmosphere or ionosphere, the thermal and transport properties of heated air are required. Such properties are also of particular interest in plasma physics, in gas laser systems, and in basic studies of airglow and the aurora. In the latter area the release of certain chemical species into the upper atmosphere results in luminous clouds that display the resonance electronic-vibrational-rotational spectrum of the released species. Such spectra are seen in rocket releases of chemicals for upper-atmosphere studies and on reentry into the atmosphere of artificial satellites. Of particular interest in this connection are the observed spectra of certain metallic oxides and air diatomic species. From band-intensity distribution of the spectra and knowledge of the /-values for electronic and vibrational transitions, the local conditions of the atmosphere can be determined.1... [Pg.227]


See other pages where THERMODYNAMICS OF RADIATION is mentioned: [Pg.484]    [Pg.485]    [Pg.487]    [Pg.4]    [Pg.283]    [Pg.284]    [Pg.286]    [Pg.288]    [Pg.290]    [Pg.292]    [Pg.294]    [Pg.296]    [Pg.484]    [Pg.485]    [Pg.487]    [Pg.4]    [Pg.283]    [Pg.284]    [Pg.286]    [Pg.288]    [Pg.290]    [Pg.292]    [Pg.294]    [Pg.296]    [Pg.387]    [Pg.248]    [Pg.43]    [Pg.77]    [Pg.408]    [Pg.354]    [Pg.520]    [Pg.263]    [Pg.120]    [Pg.275]    [Pg.97]    [Pg.187]    [Pg.43]    [Pg.77]    [Pg.4]    [Pg.8]    [Pg.136]    [Pg.163]    [Pg.322]    [Pg.562]    [Pg.759]    [Pg.970]    [Pg.1049]   


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Radiation thermodynamics

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