Interest in electromagnetism

This is not really very complicated and it applies equally well to water waves or electromagnetic radiation. What is almost needlessly complicated is the variety of units commonly used to express k and v for electromagnetic radiation. One problem is tradition, the other is the desire to avoid very large or very small numbers. Thus, as Figure 9-7 shows, we may be interested in electromagnetic wavelengths that differ by as much as a factor of 1016. Because the velocity of electromagnetic radiation in a vacuum is constant at 3 X 108 meters sec-1, the frequencies will differ by the same factor. 

The scattering of visible light by polymer solutions is our primary interest in this chapter. However, since is a function of the ratio R/X, as we saw in the last section, the phenomena we discuss are applicable to the entire range of the electromagnetic spectrum. Accordingly, a general review of the properties of this radiation and its interactions with matter is worthwhile before a specific consideration of scattering. 

Edmond Becquerel was interested in and dedicated to science in general. He was a very careful and imaginative experimenter with an acute sense of the practical aspects of science. He put great effort and insight into exploring the practical uses of physics, especially the new phenomena of electricity and magnetism or, when combined, electromagnetism. 

Tlie problem of particular interest in physics and chemistry is concerned with the interaction of electromagnetic radiation, and light in particular, with matter. The electric field of the radiation can directly perturb an atomic or molecular system. Then, as in the Stark effect, the energy of interaction - the perturbation - is given by... 

The plasma is maintained at a temperature of 10 000° C by an external radio frequency current, as described in Section 3.3. At this temperature, many molecular species are broken down, and approximately 50% of the atoms are ionized. So far this is identical to ICP-OES, but for ICP-MS we are not interested in the emission of electromagnetic radiation, but rather in the creation of positive ions. To transfer a representative sample of this plasma ion population to the mass spectrometer, there is a special interface between the plasma and the mass spectrometer. This consists of two sequential cones... 

External fields are introduced in the relativistic free-particle operator hy the minimal substitutions (17). One should at this point carefully note that the principle of minimal electromagnetic coupling requires the specification of particle charge. This becomes particularly important for the Dirac equation which describes not only the electron, but also its antiparticle, the positron. We are interested in electrons and therefore choose q = — 1 in atomic units which gives the Hamiltonian... 

When there is a single bounding surface S that can be extended to infinity where the electromagnetic field vanishes, only the space-charge parts As and < )v will contribute to the energy (21). This possibility is of special interest in this context, which concentrates mainly on photon physics. 

Infrared (IR) radiation refers broadly to that part of the electromagnetic spectrum between the visible and microwave regions. Of greatest practical use to the organic chemist is the limited portion between 4000 and 400 cm-1. There has been some interest in the near-IR (14,290-4000 cm-1) and the far-IR regions, 700-200 cm-1. 

Commercially available instruments include electromagnets of 2.114 and 2.35 Tesla (1 Tesla = 10 kilogauss). For these fields, the range of Larmor frequencies for nuclei of interest in organic structure analysis can be obtained from Fig. 2.35, e.g. ... 

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