Ellipsoids aluminum

There are claims that also aluminum produces enhancements. Liao and Stern " saw Raman scattering of p-nitrobenzoic acid adsorbed on oxide-covered ( 3-nm thickness) aluminum ellipsoids, which was 500-fold weaker than exhibited on silver. The intensities on aluminum increased by a factor of 3 changing the exciting energy from 2.2 to 2.7 eV, though the optical parameters of aluminum are rather constant in this region. Lopez-Rios et also reported surface Raman spectra from (perhaps) molecular oxygen and carbon oxides adsorbed on aluminum in UHV conditions. No SERS of pyridine was seen. 

Fig. 4. Thermal ellipsoidal drawing45 of [Li(12-crown-4)2]+ [Trip2GaGaTrip2]. Important bond distances and angles for this compound, and its aluminum analog, are given in Table II.

Fig. 14. Thermal ellipsoidal plot of Trip2AlP(l-Ad)SiPh3, which is currently the only structurally characterized unassociated aluminum diorganophosphide. [Reprinted with permission from Wehmschulte, Ruhlandt-Senge, and Power.75a Copyright 1994 American Chemical Society.]...

Fig. 5.2.6 SEM images of the ellipsoidal particles of basic aluminum sulfate prepared in the presence of 1.67 mol dm-3 chloride ions under the otherwise standard conditions. (From Ref. 1.)...

Figure 12.6 Calculated absorption spectra of aluminum spheres, randomly oriented ellipsoids (geometrical factors 0.01, 0.3, and 0.69), and a continuous distribution of ellipsoidal shapes (CDE). Below this is the real part of the Drude dielectric function.

Extinction calculations for aluminum spheres and a continuous distribution of ellipsoids (CDE) are compared in Fig. 12.6 the dielectric function was approximated by the Drude formula. The sum rule (12.32) implies that integrated absorption by an aluminum particle in air is nearly independent of its shape a change of shape merely shifts the resonance to another frequency between 0 and 15 eV, the region over which e for aluminum is negative. Thus, a distribution of shapes causes the surface plasmon band to be broadened, the... 

Figure 12.20 Extinction spectra calculated for small aluminum spheres and a continuous distribution of ellipsoids (CDE) in air (---) and in a medium with c = 2.3 (—). The circles show data...

Ellipsoidal cryptands can also be synthesized by direct alkylation procedures <77AG(E)720,80CB1487), obviating the need for a diborane or lithium aluminum hydride reduction step. In the case of [l.l.l]cryptand (15a) yields of the final amine alkylation step are enhanced by the amine proton itself acting as a template (81CC777). 

It is evident from Fig. 5 that the ratios /uly for the aluminum and the nitrogen ions increased with rising temperature. Measurements of the linear expansion coefficient (a) by the x-ray diffraction method showed that this coefficient was also anisotropic. In the temperature range 298-670°K, the linear expansion coefficient along the c axis ) was (3.0 0.2) XO d , and in the basal plane it was a y = (3.8 0.2) 10 d ". The ellipsoid of the square of the linear expansion coefficient was elongated in the basal plane (Fig. 4). 

Fig. 4. Ellipsoids of mean-square dynamic displacements of the aluminum and the nitrogen ions at 19 °C and the ellipsoid of the squares or components of the linear expansion coefficient.

Although the structural chemistry of molybdenum and vanadium phosphates is very diverse these compounds seem to be prototypes for open framework transition and main group metal phosphates. Recent results have shown that zeolite-like compounds like zinc/cobalt phosphates [731, indium phosphates [74], nickel/aluminum phosphates [75], cobalt/boron phosphates [76], manganese and cobalt phosphonates with giant 44-membered rings forming ellipsoidal cavities [77] can be synthesized. All these examples show that the diverse chemistry of octahedral-tetrahedral framework structures is a vast field where... 

Isothermal omega (cOiso) forms during aging (at temperatures up to about 475 °C, or 890 °F) for alloys containing intermediate amounts of beta stabilizers. Ellipsoidal and cuboidal morphologies have been observed, depending on the misfit between the coherent C0is<, precipitates and the beta matrix. The stability of (Oiso depends on the relative concentration of alpha and beta stabilizers such as aluminum and vanadium (see Fig. 7). 

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