Electronic elementary excitation

More advanced teclmiques take into account quasiparticle corrections to the DFT-LDA eigenvalues. Quasiparticles are a way of conceptualizing the elementary excitations in electronic systems. They can be detennined in band stmcture calculations that properly include the effects of exchange and correlation. In the... 

Chemiluminescence is light emission from the relaxation of electrons populating excited states in an elementary step of a chemical reaction. Since, the process of population of excited states is related kinetically to the kinetics of the given chemical reaction, the emission of chemiluminescence over time should thus be related to the rate of the chemical reaction. 

All occupation number vectors in F(m,N) can be obtained from an occupation number vector I n> with N electrons by applying one or several elementary excitation operators on I n>. If a single excitation operator is applied we obtain a single excitation, if two excitation operators are involved, we obtain a double excitation, etc. 

The conduction electrons move independently in the liquid. This latter assumption raises some difficulties, since the Coulomb interaction between the electrons is large. The difficulty is overcome by realizing that we need not consider the motions of electrons which are strongly correlated, but only the motions of Landau quasi particles (25), each electron being surrounded by a correlation hole. In more formal language, we may say that the quasi particles stand in one-to-one correspondence with the electrons and represent the elementary excitations of the Fermi liquid. 

An important prediction of LL theory is that the low-energy elementary excitations of a one-dimensional metal are not electronic quasiparticles, as... 

The conductance for a spacing of 2 /xm between gates g and g2 is shown in Fig. 2. The measured bright and dark curves in the plot can be interpreted as spectral peaks tracing out the dispersions of the elementary excitations in the wires. [3] In the case of noninteracting electrons, the curves are expected to map out parabolas defining the continua of electron-hole excitations across... 

Gordeev Yu.S, Mikuushkin V.M., Shnitov V.V. Spectra of elementary excitations of C6o fullerite and influence on their of electron irradiation. Fiz.Tv.Tela (in Russian) 2000 42 371-377. 

The elementary excitations of a conjugated polymer chain can be described within the mono-electronic approach as electron and hole quasiparticles [74] in a one-dimensional band structure, possibly weakly bound into extended Wannier-type excitons [71,75]. Within this framework, electron-phonon interactions lead to a peculiar family of exotic excitations including solitons, polarons, polaron pairs and bipolarons. In many cases, however, disorder is so significant that the polymer films are better described as an ensemble of relatively short conjugated segments [76], essentially behaving... 

In order to derive Rosenfeld s equation from Eq. (3.14) we must make some such argument as the following. Let us assume that the self-consistent quantum field theory (Sect. 2) has been worked through and has yielded composite -particle elementary excitations that we identify with molecules. We can then define a charge and current density for a molecule containing n electrons and nuclei,... 

More than 15 years after the discovery of high-Tc superconductivity in layered cuprates its mechanism is still under debate. This has to do with the asymmetry of physical properties between the electron-doped and hole-doped side of the complex phase diagram, temperature vs. doping, T(x), and with the fact that no consensus has been reached about the question what are the key experiments a theory of high-Tc superconductivity must be able to explain. In this paper we argue that the elementary excitations and their interdependence with spin excitations in the cuprates are of central interest in order to learn more about the correlations in general and, in particular, about the mechanism for Cooper-pairing in these systems. 

Exciton — A bound and thus localized pair of an - electron in the conduction band and a hole in the valence band. An exciton is an elementary excitation and quasiparticle in solids. See also Frenkel, defects in solids. Ref [i] Eliott SR (1998) The physics and chemistry of solids. Wiley, Chichester... 

Band Structure Calculations and Experimental Results The spectroscopic properties discussed above are related primarily to intrachain electronic structure. One exception is the stability of gap states (e.g., polarons) versus the three-dimensional interaction effects mentioned in Chapter 11, Section IV.D. Energy and charge transport are, of course, dependent on interchain transfers. So while there are only a few three-dimensional band structure calculations (e.g., for PA [184] and PPV [185]), there are many theoretical calculations concerning infinite perfectly periodic one-dimensinal chains, the effects of local perturbations, and the elementary excitations of these chains solitons, polarons, and bipolarons. Only a few hints of that work will be given here. It has been discussed and reviewed several times (see, e.g., Refs. 186 to 188). 

If the lowest energy elementary excitations are bound singlet and triplet excitons, the theoretical maximum EL quantum efficiency is 25% of the photoluminescence (PL) quantum efficiency. On the contrary, if separated electron and hole polarons are the elementary excitations, the maximum theoretical EL efficiency can approach unity. Thus, a quantitative comparison of the quantum efficiencies for electroluminescence and photoluminescence can, in principle, provide fundamental information on the nature of the excited states. 

The properties of the target are described by its dielectric function s(k, a>), where hk and Hm represent the momentum and energy transfer to the system in an elementary inelastic process. This approach has the possibility of describing in a condensed way the screening of the intruder ions as well as the excitations of valence electrons in the solid, including both collective and single-particle (or electron-hole) excitations [13,14]. The stopping power in... 

Elementary Excitation in the Superfluid Clusters. The existence of a roton-type collective excitation spectrum in large ( He)jy clusters N = lO -lO ) at 0.4 K was established from electronic spectroscopy of large molecules (e.g., glyoxal [70]) which manifests coupled electronic-roton excitations [70]. 

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