Current perpendicular to the plane

It is also possible to electrodeposit multilayers in cylindrical pores of a suitable etched polymer membrane. Typically, wires with diameters of about 100 nm and length of 5-10 fim can be obtained. The deposition cycles are similar to the ones described above. Magnetoresistance [this is a term describing the relative decrease (increase) in electrical resistance of a material when subjected to a magnetic field longitudinally (transversely) to the current flow] measurements with the current perpendicular to the planes are possible. In addition, giant magnetoresistance (GMR defined below) effects may be observed as well. 

Fig. 10. Cross-sectional drawing of a vertical cavity surface emitting laser (VCSEL). Proton implantation is used to channel the current through a small active region. Light is emitted in the direction perpendicular to the plane of the wafer. This makes preparation of two-dimensional arrays quite easy.

Davis et. al. (64) have calculated the steady-state thin-layer current component for a series of electrode geometries. In their derivation, these authors have assumed that the flux between the electrodes is one-dimensional (perpendicular to the plane). Particularly relevant to the STM geometry are the equations for the current in a conical electrode/planar electrode TLC, Icon, and those for a hemispherical electrode/planar electrode TLC, Xhsph (64> ... 

Let us consider a metal wire in the form of a circle. If a magnetic field is applied perpendicularly to the plane of the circle a current is induced in the wire. Corresponding to this current there is a magnetic field, resembling that of a magnetic dipole with orientation opposed to the field (Lena s law). 

Fig. 7. A plot of the upheld ring current shifts measured in porphyrins, and in phtalo-cyanine model complexes where aliphatic hydrocarbons were attached to the central metal ion (Caughey and Ibers (18) Esposito et al. (30)). The positions of the observed protons were derived within the accuracy indicated by the ellipses from the known molecular structures. Z and r are the distances from the ring center perpendicular to the plane, and in the plane of the ring, respectively. The dashed line indicates the van der Waal thickness of the porphyrin ring. (Reproduced from ref. (99))...

With current instruments it is possible to make spatial maps of the emission from different species in the Red Rectangle. These maps might provide valuable clues to the origin of different spectroscopic features. For example, in the spectrum of the Red Rectangle, the emission features which correspond to the diffuse interstellar bands are concentrated in what appears to be two hollow cones oriented perpendicular to the plane of this bipolar system (Schmidt Witt 1991). This hollow cone is similar to that proposed by Jura Kroto (1990) to explain the observed (Nguyen-Q-Rieu et al. 1986) HC,N emission (see around AFGL 2688, the Egg Nebula ), a very well studied carbon-rich object that appears to be in transition from a red giant to a planetary nebula. 

The current understanding of the structure of benzene is based on molecular orbital (MO) theory. The six carbon atoms of benzene are sp hybridized. The three sp- hybrid orbitals of each carbon atom, which are arranged at angles of 120°, overlap with those of two other carbon atoms and with the s orbital of a hydrogen atom to form the planar a-bonded skeleton of the benzene ring. The p orbital associated with each carbon contains one electron and is perpendicular to the plane of the ring. 

The currently determined X-ray structure of a tetranuclear heterobimetallic isopropoxide, ErAI3(0-/-Pr),2 (Fig. 25) (251), possesses a noncrystallographi-cally imposed C3 point symmetry, with the rotation axis perpendicular to the plane through the aluminum atoms. The coordination geometry around the erbium atom is a distorted trigonal prism, in contrast to the ideal octahedral coordination for the central aluminum atom in the structure of A1A13(0-/-Pr),2 (see Fig. 2). 

The mycolic esters at the nomeducing ends of the AG present a formidable hydro-phobic barrier that prevents the passage of antibiotics into the organism [28]. The currently accepted structural model of the mycolyl-AG complex was initially proposed by Mitmikin in 1982 [24] and is illustrated in Figure 4. In this model the mycolic acid chains are packed side by side, perpendicular to the plane of the cy-... 

Traditional bonding descriptions for the 6-membered rings have involved N(2/>)-P(3(i) overlap, both in and perpendicular to the plane of the P3N3-ring. However, this model is not consistent with current opinion that phosphorus makes little or no use of its M orbitals. Structure 14.72 provides another resonance form for a 6-membered cyclophospha-zene, and is consistent with the observed P—N bond equivalence, as well as the observation that the N and P atoms are subject to attack by electrophiles and nucleophiles, respectively. Theoretical results support the highly polarized P 5+ N bonds and the absence of aromatic character in the P3N3-ring. ... 

An electric current flowing round a coil of radius r exerts a force F on a small magnet whose axis is at some point on a line drawn through the centre and perpendicular to the plane of... 

The current density is an observable which can be visualised for a molecule through oriented contour lines. Usually the applied field is perpendicular to the plane of the paper, and points inward. Clockwise circulation corresponds to a diamagnetic current since it induces an internal magnetic field pointing against the applied field [21]. 

---