Radiation with matter

If the parent half-life is greater than the daughter half-life (say a factor of 10-100), and also if the time of decay (t) is very long, then e Ad( is almost zero compared with e Ap(. Then 

If the parent half-life is much greater than the daughter half-life (by factors of hundreds or thousands), then Ap is very negligible compared with Ad. Then Eq. (1.15) becomes 

This equation represents a secular equilibrium in which the daughter activity becomes equal to the parent activity, and the daughter decays with the half-life of the parent. The 82Sr-82Rb generator is an example of secular equilibrium. 

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As discussed in more detail elsewhere in this encyclopaedia, many optical spectroscopic methods have been developed over the last century for the characterization of bulk materials. In general, optical spectroscopies make use of the interaction of electromagnetic radiation with matter to extract molecular parameters from the substances being studied. The methods employed usually rely on the examination of the radiation absorbed. 

The interaction of electromagnetic radiation with matter can be explained using either the electric field or the magnetic field. For this reason, only the electric field component is shown in Figure 10.2. The oscillating electric field is described by a sine wave of the form... 

The following sources present a theoretical treatment of the interaction of electromagnetic radiation with matter. 

The plane of polarization is conventionally taken to be the plane containing the direction of E and that of propagation in Figure 2.1 this is the xy plane. The reason for this choice is that interaction of electromagnetic radiation with matter is more commonly through the electric component. 

V. S. Gorelik, in Temporal Characteristics of Laser Pulses and Interaction of Laser Radiation with Matter, N. G. Basov (ed.). Consultants Bureau, New York, 1977... 

The physical basis of spectroscopy is the interaction of light with matter. The main types of interaction of electromagnetic radiation with matter are absorption, reflection, excitation-emission (fluorescence, phosphorescence, luminescence), scattering, diffraction, and photochemical reaction (absorbance and bond breaking). Radiation damage may occur. Traditionally, spectroscopy is the measurement of light intensity... 

The field of science that studies the interaction of electromagnetic radiation with matter is known as spectroscopy. Spectroscopic studies on the wavelength, the intensity of the radiation absorbed, emitted, or scattered by a sample, or how the intensity of the radiation changes as a function of its energy and wavelength, provide accurate tools for studying the composition and structure of many materials (Davies and Creaser 1991 Creaser and Davies 1988). 

Interaction of Radiation with Matter Energy Transfer from Fast Charged Particles... 

Interactions of Ultraviolet and Microwave Radiation with Matter... 

Most of what we know about the structure of atoms and molecules has been obtained by studying the interaction of electromagnetic radiation with matter. Line spectra reveal the existence of shells of different energy where electrons are held in atoms. From the study of molecules by means of infrared spectroscopy we obtain information about vibrational and rotational states of molecules. The types of bonds present, the geometry of the molecule, and even bond lengths may be determined in specific cases. The spectroscopic technique known as photoelectron spectroscopy (PES) has been of enormous importance in determining how electrons are bound in molecules. This technique provides direct information on the energies of molecular orbitals in molecules. 

Concepts Interaction of radiation with matter Light and matter interact by scatter and absorption. Absorption only occurs when the colour of the radiation is the same as an energy separation within the molecule, but scatter occurs at all wavelengths... 

The fundamentals of the interaction of radiation with matter have been considered in several texts (1-8). 

There are many subtleties In the interaction of ionising radiation with matter for more details, reference should be made to the many texts (2-4), reports (5-8) and papers In the literature. 

Measurements of the intensity and wavelength of radiation that is either absorbed or emitted provide the basis for sensitive methods of detection and quantitation. Absorption spectroscopy is most frequently used in the quantitation of molecules but is also an important technique in the quantitation of some atoms. Emission spectroscopy covers several techniques that involve the emission of radiation by either atoms or molecules but vary in the manner in which the emission is induced. Photometry is the measurement of the intensity of radiation and is probably the most commonly used technique in biochemistry. In order to use photometric instruments correctly and to be able to develop and modify spectroscopic techniques it is necessary to understand the principles of the interaction of radiation with matter. 

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