Photoelectric effect and

Einstein, in 1906, applied this theory to the photoelectric effect and showed that... 

Absorption Coefficient—Fractional absorption of the energy of an unscattered beam of x- or gamma-radiation per unit thickness (linear absorption coefficient), per unit mass (mass absorption coefficient), or per atom (atomic absorption coefficient) of absorber, due to transfer of energy to the absorber. The total absorption coefficient is the sum of individual energy absorption processes (see Compton Effect, Photoelectric Effect, and Pair Production). 

Schrodinger s equation is widely known as a wave equation and the quantum formalism developed on the basis thereof is called wave mechanics. This terminology reflects historical developments in the theory of matter following various conjectures and experimental demonstration that matter and radiation alike, both exhibit wave-like and particle-like behaviour under appropriate conditions. The synthesis of quantum theory and a wave model was first achieved by De Broglie. By analogy with the dual character of light as revealed by the photoelectric effect and the incoherent Compton scattering... 

But light is also a particle. Some properties of light cannot be explained by the wave-like nature of light, such as the photoelectric effect and blackbody radiation (see Section 9.4), so we also need to think of light comprising particles, i.e. photons. Each photon has a direction as it travels. A photon moves in a straight line, just like a tennis ball would in the absence of gravity, until it interacts in some way (either it reflects or is absorbed). 

It was noted earlier that EXAFS is a result of two fundamental processes (a) K- (or L-) absorption of an X-ray photon which is the photoelectric effect and (b) an effective diffraction of the electron so emitted. In the case of an isolated absorbing atom (absorber) one sees only the characteristic rise in absorbance, // (= In /(,//), at the energy corresponding to the edge and an exponential decrease thereafter. When the absorber is surrounded by other atoms, // exhibits undulations sometimes up to 2000 eV beyond the edge. Undulations starting 30 eV beyond the edge constitute the EXAFS. As an example, the EXAFS of a bimetallic catalyst is shown in Fig. 2.12. 

Depending on their function, radiometers can be either thermal or photon detectors. In thermal detectors, the incident photon energy is converted into heat, which is then measured. The measured data are independent of wavelength. Photon detectors are based on photoelectric effect and measure spectrum intensity. The results are dependent on wavelength. 

Describe how the photoelectric effect and electron diffraction demonstrate the particle-like character of radiation and the wave-like character of particles respectively. Show how Heisenberg s uncertainty principle embraces the concept of wave particle duality. 

Photon detectors are based on photoelectric effect and measure spectrum intensity. The results are dependent on wavelength. 

A distinction must be made between Ihe coniacl potentials in air and the so-called "intrinsic contact potentials in a vacuum with all adsorbed gases removed According to Millikan, the intrinsic potential difference between two metals A and B is expressed by VAfl = (i(v4 - vg /e. in which It is Planck s constant. t, i and ug are the critical frequencies of phutoeleclric emission for the two metals (see Photoelectric Effect), and e is the electronic charge. In any ease, if (he electronic work funclions of the metals are )>,t and ps- the contact potential difference is V. sa = [p./, - pn)/e. The work funclions. and hence V, . are in general dependent upon the medium surrounding the metals. Accurate measurements of these potentials are. unlorlunnlely, very difficult. 

Sommerfeld applied the theory of quanta to the emission of X- and y-rays, to the photoelectric effect, and sketched the theory of the ionization potential. At the beginning of his paper he discussed in some detail the relationship observed in the emission of X- (or y-) rays by cathode (or 0) rays and arrived at the conclusion that large quantities of energy are emitted in shorter times and small quantities of energy in larger times. 9 According to Sommerfeld this empirical result speaks in favor of the central role played in atomic and molecular phenomena by the quantum of action h introduced by Planck, the dimensions of which are energy multiplied by time. 

For normal chemical systems, the characterization of mixtures of compounds is undesirable and generally unnecessary if means of separation of the components are available. However, photochromic systems inherently display properties of mixtures except when the system is completely converted to either of its forms. This causes measurements of heats of combustion, photoelectric effects, and electrical conductivity to be particularly difficult. A variety of such studies is presented in the following sections to illustrate the utility of these measurements. 

The first convincing description of stationary quantum states was provided by the assumed wave nature of matter proposed by Louis de Broglie. The proposal had its roots in Einstein s explanation of the photoelectric effect and Compton s analysis of X-ray scattering. 

It was mentioned in the chapter on electrons that when ultra-violet light falls on a metal like zinc, it causes electrons to be emitted by the metal. This effect is called the photoelectric effect, and it is found that it cannot be explained on... 

Describe the photoelectric effect, and discnss how related paradoxes of classical physics were resolved by quantum mechanics (Section 4.4, Problems 23 and 24). 

Using the law of conservation of energy, relate the work function of a metal to the wavelength of light used to eject electrons in the photoelectric effect and the kinetic energy of those electrons (Section 4.4, Problems 25-28). 

Quantum mechanics represents one of the cornerstones of modem physics. Though there were a variety of different clues (such as the ultraviolet catastrophe associated with blackbody radiation, the low-temperature specific heats of solids, the photoelectric effect and the existence of discrete spectral lines) which each pointed towards quantum mechanics in its own way, we will focus on one of these threads, the so-called wave-particle duality, since this duality can at least point us in the direction of the Schrodinger equation. 

In that year, he published three important papers the theory of Brownian motion an explanation of the photoelectric effect and the special theory of relativity. According to his Brownian motion theory, the fluid molecules move at random by thermal movement, and therefore a small particle would receive a random number of impacts of random strength and from random directions in any short period. If the particle is sufficiently small, this random collision by the fluid molecules would cause... 

Fig. 1(a). Mass attenuation coefficient of X-ray and 7-photons in water, aluminium, iron and lead [2], (Note the relatively small dependence on chemical structure except at low energies, due to the photoelectric effect and, at high energies, to pair production, (b) Total energy absorption due to photoelectric effect, Compton scattering and pair production [2],... 

Three phenomena involving matter and light confounded physicists at the turn of the 20 century (1) blackbody radiation, (2) the photoelectric effect, and... 

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