Electronic dimensionality

Keywords Charge transfer solid Electronic dimensionality Functional organic solid Ionicity diagram Organic metal Organic superconductor Phase transition Quantum spin liquid state Switching... 

Fig. 3 Strategy for chemical modification of the TTF molecule to increase or decrease the electronic dimensionality (D) by the aid of enhance or suppress the self-aggregation ability of the donor molecules, respectively. Typical Fermi surfaces of TMTSF (a (TMTSF)2NbF6), BO (b (BO)2.4l3), TTP (c (BEDT-TTP)2l3, Scheme 8) [88], ET (d / -(ET)2l3), and EDO (e (EDO)2PEg) CT solids are depicted. PIPT photo-induced-phase-transition...

Thus it is clear from this study that models which successfully dominate conventional 3D semiconductors lead to pathological solutions on restricting the electron dimensionality. At best they can describe the electron before the SWAP forms, or in a duration when the SWAP may temporeirily break up. In no way can they explain the facts in PDA. 

Several works have shown the real effect of a reduced electronic dimensionality in these molecular compounds, especially for the q-lD Bechgaard salts [458] but existing also under a weaker form in q-2D systems. In these q-lD systems, an interchain coupling exists which controls the nature of the phase transition [459]. The g-ology model predicts the occurrence of several types of order [460] ... 

As a complementary point to the spin susceptibility measurements, the dynamic approach is also sensitive to the electronic correlations but more significantly to the electronic dimensionality. Thanks to selected examples, we will show that the g-factor and the linewidth characteristics are very powerful probes for the phase identifications and the occurrence of phase transitions as long as single crystals are investigated. 

As shown earlier the conductivity properties are strongly related to the structural classification, which has been already presented. It appears nevertheless that we are not always in the presence of ideal tri-periodic molecular systems but with different kinds of disorders. The influence of these disorders is a rather complicated effect. It depends roughly on two parameters, which are the electronic dimensionality and the nature of the local perturbation. As pointed out in Section 4.1, in pure ID systems any disorder will induce an electronic localization. It appears therefore that this effect will be efficient in disordered ID conductors but weaker in q-2D ones (see Figure 3.12 for a topological classification). 

Gordon R., Bender R., Herman G.T. Algebraic reconstruction techniques (ART) for three-dimensional electron micrographs and X-ray photography., J. Theor. Biol., V. 29, 1970, p. 471-481. 

Another important application area is the non-destructive defectoscopy of electronic components. Fig.2a shows an X-ray shadow image of a SMC LED. The 3-dimensional displacement of internal parts can only be visualized non-destructively in the tomographic reconstmction. Reconstructed cross sections through this LED are shown in Fig.2b. In the same way most electronic components in plastic and thin metal cases can be visualized. Even small electronic assemblies like hybrid ICs, magnetic heads, microphones, ABS-sensors can be tested by microtomograpical methods. 

Therefore it is reasonable to prepare already the data acquisition for a three dimensional evaluation in cone-beam-technique by means of two-dimensional detectors. The system is already prepared to integrate a second detector- system for this purpose. An array of up to four flat panel detectors is foreseen. The detector- elements are based on amorphous silicon. Because of the high photon energy and the high dose rates special attention was necessary to protect the read-out electronics. Details of the detector arrangement and the software for reconstruction, visualisation and comparison between the CT results and CAD data are part of a separate paper during this conference [2]. 

Gallagher Feeder S M and Jonas D 1999 Two-dimensional electronic correlation and relaxation spectra theory and model calculations J. Phys. Chem. A 102 10 489-505... 

Surfaces are found to exliibit properties that are different from those of the bulk material. In the bulk, each atom is bonded to other atoms m all tliree dimensions. In fact, it is this infinite periodicity in tliree dimensions that gives rise to the power of condensed matter physics. At a surface, however, the tliree-dimensional periodicity is broken. This causes the surface atoms to respond to this change in their local enviromnent by adjusting tiieir geometric and electronic structures. The physics and chemistry of clean surfaces is discussed in section Al.7.2. 

Surface states can be divided into those that are intrinsic to a well ordered crystal surface with two-dimensional periodicity, and those that are extrinsic [25]. Intrinsic states include those that are associated with relaxation and reconstruction. Note, however, that even in a bulk-tenuinated surface, the outemiost atoms are in a different electronic enviromuent than the substrate atoms, which can also lead to intrinsic surface states. Extrinsic surface states are associated with imperfections in the perfect order of the surface region. Extrinsic states can also be fomied by an adsorbate, as discussed below. 

There are many other experiments in which surface atoms have been purposely moved, removed or chemically modified with a scanning probe tip. For example, atoms on a surface have been induced to move via interaction with the large electric field associated with an STM tip [78]. A scaiming force microscope has been used to create three-dimensional nanostructures by pushing adsorbed particles with the tip [79]. In addition, the electrons that are tunnelling from an STM tip to the sample can be used as sources of electrons for stimulated desorption [80]. The tuimelling electrons have also been used to promote dissociation of adsorbed O2 molecules on metal or semiconductor surfaces [81, 82]. 

Lee M, Flaseltine J N, Smith A B III and Flochstrasser R M 1989 Isomerization processes of electronically excited stiibene and diphenylbutadiene in liquids Are they one-dimensional J. Am. Chem. See. Ill 5044-51... 

Plenary 10. Hiro-o Hamaguchi, e-mail address lilrama ,chem.s.u-tokvo.ac.ip (time and polarization resolved multiplex 2D-CARS). Two-dimensional (tune and frequency) CARS using broadband dye source and streak camera timing. Studies dynamic behaviour of excited (pumped) electronic states. Follows energy flow within excited molecules. Polarization control of phase of signal (NR background suppression). 

A succinct picture of the nature of high-energy electron scattering is provided by the Bethe surface [4], a tlnee-dimensional plot of the generalized oscillator strength as a fiinction of the logaritlnn of the square of the... 

The otiier type of noncrystalline solid was discovered in the 1980s in certain rapidly cooled alloy systems. D Shechtman and coworkers [15] observed electron diffraction patterns with sharp spots with fivefold rotational synnnetry, a syimnetry that had been, until that time, assumed to be impossible. It is easy to show that it is impossible to fill two- or tliree-dimensional space with identical objects that have rotational symmetries of orders other than two, tliree, four or six, and it had been assumed that the long-range periodicity necessary to produce a diffraction pattern with sharp spots could only exist in materials made by the stacking of identical unit cells. The materials that produced these diffraction patterns, but clearly could not be crystals, became known as quasicrystals. 

X-ray scattering arises from fluctuations in electron density. The general expression of the absolute scattered intensity (simplified as I(q) from now on) from the tliree-dimensional objects iimnersed in a different... 

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