Electricity, interaction with matter

Electricity interacts with matter because electrons are part of matter and form the chemical bonds. When electrons are transferred from one molecule to the other we call it a redox reaction. Since electric current is the movement of electrons, micro electric currents then exist in the solution where redox reactions take place. If all these micro-currents were made to flow in one direction we should be able to measure them as one macro electric current. Batteries (which are also called galvanic cells or voltaic piles ) are devices which do exactly this they produce electric current by making redox reactions take place at electrodes, i.e. at the metal solution boundary. The metal can be either the source or the sink for electrons. Thus electric current is made to flow from the metal into the solution or from the solution into the metal. Can one do the reverse Can one induce redox reactions by passing through the solution current from a source The answer is definitely yes . The instrument by which such changes are produced is an electrolytic cell . A simple cell can be constructed from two pieces of dissimilar metals dipping into a solution of some electrolyte in a beaker. The metal pieces are now the electrodes. This book is concerned with chemical reactions produced by electric current or electric current produced by chemical reactions at electrodes. It is concerned with redox reactions in cells. 

Electric Fields and Their Interaction with Matter... 

As our discussion of scattering proceeds, we shall examine the coupling between the oscillating electrical field of light and the electrons of the scatterer in detail. First, it is useful to consider the interaction of an electric field with matter, as this manifests itself in the dielectric behavior of a substance. This will not only introduce us to the field-matter interaction, but will also provide some relationships which will be useful later. 

The first theoretical attempts in the field of time-resolved X-ray diffraction were entirely empirical. More precise theoretical work appeared only in the late 1990s and is due to Wilson et al. [13-16]. However, this theoretical work still remained preliminary. A really satisfactory approach must be statistical. In fact, macroscopic transport coefficients like diffusion constant or chemical rate constant break down at ultrashort time scales. Even the notion of a molecule becomes ambiguous at which interatomic distance can the atoms A and B of a molecule A-B be considered to be free Another element of consideration is that the electric field of the laser pump is strong, and that its interaction with matter is nonlinear. What is needed is thus a statistical theory reminiscent of those from time-resolved optical spectroscopy. A theory of this sort was elaborated by Bratos and co-workers and was published over the last few years [17-19]. 

Also very broad, complex and of great importance in physics and chemistry is the sixth topic, where electric and magnetic fields interact with matter. Condensed matter is a field where theoretical studies are performed from few-atom clusters to crystals, materials and interfaces the theory becomes more and more complex and new scientific ideas and models are sought. The theory with which to study chemical reactions and... 

Although the Kramers-Kronig relations do not follow directly from physical reasoning, they are not devoid of physical content underlying their derivation are the assumptions of linearity and causality and restrictions on the asymptotic behavior of x> As we shall see in Chapter 9, the required asymptotic behavior of x is a physical consequence of the interaction of a frequency-dependent electric field with matter. 

The electrical interaction with the field is a matter of the work of taking a charged ion through a distance Xj — jq, i.e., from the OHP to the IHP. The electrical field, X, in a parallel-plate condenser is q /EEq. From Eq. (6.20), the difference in energy in bringing a test charge z e0 from jq to x, in this electrical field is... 

James Clerk Maxwell derived the Maxwell Equations in 1864. These expressions completely describe electric and magnetic fields and their interaction with matter. Also see Ludwig Boltzmann below for Maxwell s contribution to thermodynamics. 

Optical nonlinearities can be explained by considering the interaction of strong electric fields with matter. If the fields have optical frequencies, the phenomena resulting from the nonlinear interactions are called nonlinear optical phenomena. Most texts on nonlinear optics (e.g., Refs. 22-25) begin the discussion of this area from considerations of macroscopic relations between the vector quantities P (the polarization vector), D (the displacement vector), and E (the electric field vector). Chemists, however, consider the molecular origin of physical phenomena, so the description of NLO phenomena that follows starts from consideration of the behavior of a single molecule in a strong electric field. 

When light interacts with matter, and the photons are not absorbed, it does so by inducing a polarization in the medium. Since the interaction energy between the electric field of the incident radiation and the molecules making up the medium is small compared to the total energy of the molecules, the incident radiation can be treated as a perturbation to the total energy of the medium. (This is true for pulsed laser beams as well as ambient light [13].) Therefore, the polarization of the medium, P, can be expanded as a power series in the electric field [13,14]. 

There are two inherently different methods by which an electric current interacts with matter (1) An electric current can cause a chemical reaction. (2) A chemical reaction can produce an electric current. The first of these is done in an electrolysis cell, and the second in a voltaic cell, also called a galvanic cell. Two entirely different sorts of calculations are generally used for the two kinds of cells. (Although the same type of calculations done for electrolysis cells can be done for voltaic cells, they are practically never asked for.)... 

To calculate the quantities of electricity and electrical energy interacting with matter, we must learn the electrical units involved ... 

Radiation interacts with matter through the effects of the electric field vector on the electron distributions in molecules. Absorption of radiation involves raising a system from one energy level to a higher level by the absorption of a quantum of energy (a photon). Elastic scattering of radiaLion involves no such quantum jumps and can be discussed in classical terms. ... 

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