Ionizing radiation basic concepts

Absorbed dose is a fundamental and basic physical quantity which can be used in all fields where ionizing radiations are used. It is directly related to the physical, chemical, and biological effects produced by the irradiation. The concept of absorbed dose thus has broad applications and is indeed widely used. Metrological institutions provide standards and calibration of instruments in terms of absorbed dose. 

Abstract Photochemistry is concerned with the interaction between light and matter. The present chapter outlines the basic concepts of photochemistry in order to provide a foundation for the various aspects of environmental photochemistry explored later in the book. Electronically excited states are produced by the absorption of radiation in the visible and ultraviolet regions of the spectrum. The excited states that can be produced depend on the electronic structure of the absorbing species. Excited molecules can suffer a variety of fates together, these fates make up the various aspects of photochemistry. They include dissociation, ionization and isomerization emission of luminescent radiation as fluorescence or phosphorescence and transfer of energy by intramolecular processes to generate electronic states different from those first excited, or by intermo-lecular processes to produce electronically excited states of molecules chemically different from those in which the absorption first occurred. Each of these processes is described in the chapter, and the ideas of quantum yields and photonic efficiencies are introduced to provide a quantitative expression of their relative contributions. 

The basic principle of the VK-300 safety design is consistent implementation of the defence-in-depth concept based on a system of physical barriers to ionizing radiation and radioactive substance propagation to the environment. The system of barriers incorporates ... 

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