Energy, of electromagnetic waves

Describe the relationship among frequency, wavelength, and energy of electromagnetic waves. 

Thus, the energy of electromagnetic waves is directly proportional to the reciprocal wavelength. In particular in vibrational spectroscopy, the reciprocal wavelength is used and denoted as wavenumber k ... 

The thermal energy of the hot source is converted into the energy of electromagnetic waves. These waves travel through space into straight lines and strike a cold surface. The waves that strike the cold body are absorbed by that body and converted back to thermal energy or heat. When thermal radiations falls upon a body, part is absorbed by the body in the form of heat, part is reflected back into space and in some case part can be transmitted through the body. 

Each body having a temperate above absolute zero radiates energy in the form of electromagnetic waves. The amount of energy emitted is dependent on the temperature and on the emissivity of the material. The wavelength or frequency distribution (the spectrum) of the emitted radiation is dependent on the absolute temperature of the body and on the surface properties. 

Radiation. All materials radiate thermal energy in the form of electromagnetic waves. When this radiation falls on a second body it may be partially reflected, transmitted, or absorbed. It is only the fraction that is absorbed that appears as heat in the body. 

Radiant Energy—The energy of electromagnetic radiation, such as radio waves, visible light, x and gamma rays. 

If the effect of the temperature on reaction rate is well known, and is very easy to express, the problem is very different for effects of electromagnetic waves. What can be expected from the orienting action of electromagnetic fields at molecular levels Are electromagnetic fields able to enhance or modify collisions between reagents All these questions are raised by the use of microwaves energy in chemistry. 

The spectrum of electromagnetic waves, showing the relationship between wavelength, frequency, and energy... 

Figure 32.1 The spectrum of electromagnetic waves, showing the relationship between wavelength, frequency, and energy. (Modified from Kiefer, J. 1990. Biological Radiation Effects. Springer-Verlag, Berlin. 444 pp.)...

There are two principle ways for optical detection of protein concentrations either the macromolecule or its label emits energy (after excitation by light) -then a fluorescence signal can be measured or it absorbs energy from electromagnetic waves passing the sample - then the optical absorption of the sample can be measured by UV/Vis spectroscopy and concentrations can be calculated according to Lambert-Beers Law. 

The transfer or conversion of energy is always associated with the emission of electromagnetic waves. We met this concept in its simplest form in Chapter 2, when we looked at the transfer of infrared radiation (i.e. heat). This emission of photons occurs because all objects contain electrically charged particles and, whenever an electrically charged particles accelerates, it emits electromagnetic waves. 

At the end of the nineteenth century classical physics assumed it had achieved a grand synthesis. The universe was thought of as comprising either matter or radiation as illustrated schematically in Fig. 2.1. The former consisted of point particles which were characterized by their energy E and momentum p and which behaved subject to Newton s laws of motion. The latter consisted of electromagnetic waves which were characterized by their angular frequency and wave vector and which satisfied Maxwell s recently discovered equations, ( = 2nv and — 2njX where v and X are the vibrational frequency... 

RADIATION. 1. The emission and propagation of energy through space or through a material medium in the form of waves for instance, the emission and propagation of electromagnetic waves, or of sound and clastic waves. 

Radiation may consist of particles, of electromagnetic waves, and of compres-sional (i.e. sound) waves. Thus a discussion of the chemical effects of low energy radiation could have a vast scope and would be very superficial and indeed meaningless unless limited carefully. Such a limitation must needs be arbitrary. Since the action of compressional waves is different in character from that of either moving charged particles or electromagnetic waves we will omit completely any discussion of their effects. 

It turns out that electromagnetic waves exhibit properties of both waves and particles, or equally valid, electromagnetic waves are neither waves nor particles. This fundamental paradox is at the heart of quantum theory. You can perform experiments that unequivocally demonstrate light is definitely a wave. You can also perform experiments that unequivocally demonstrate light is definitely a particle. Nonetheless, there is one important relationship that allows the energy of electromagnetic radiation to be calculated if the frequency or wavelength is known ... 

Charged point defects on regular lattice positions can also contribute to additional losses the translation invariance, which forbids the interaction of electromagnetic waves with acoustic phonons, is perturbed due to charged defects at random positions. Such single-phonon processes are much more effective than the two- or three phonon processes discussed before, because the energy of the acoustic branches goes to zero at the T point of the Brillouin zone. Until now, only a classical approach to account for these losses exists, which has been... 

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