Electric susceptibility measurements

Although it is required to refine the above condition I in actuality, this rather simple but impressive prediction seems to have much stimulated the experiments on the electrical-conductivity measurement and the related solid-state properties in spite of technological difficulties in purification of the CNT sample and in direct measurement of its electrical conductivity (see Chap. 10). For instance, for MWCNT, a direct conductivity measurement has proved the existence of metallic sample [7]. The electron spin resonance (ESR) (see Chap. 8) [8] and the C nuclear magnetic resonance (NMR) [9] measurements have also proved that MWCNT can show metallic property based on the Pauli susceptibility and Korringa-like relation, respectively. On the other hand, existence of semiconductive MWCNT sample has also been shown by the ESR measurement [ 10], For SWCNT, a combination of direct electrical conductivity and the ESR measurements has confirmed the metallic property of the sample employed therein [11]. More recently, bandgap values of several SWCNT... 

Si(Pc)0] (S04)o.09)n> i-s limited by the oxidative stability of the sulfate anion. Thermoelectric power, optical reflectivity, magnetic susceptibility, and four-probe electrical conductivity measurements evidence behavior typical of an [Si(PcP+)0]n compound where p 0.20. That is, there is no evidence that the more concentrated counterion charge has induced significant localization of the band structure. 

That the Pd-H system is composed of the units Pd and PdH has been suggested by Linde and Borelius on the basis of experiments on the behavior of the electrical resistance. Oxley7 has also suggested on the basis of susceptibility measurements that the hydrogen is in intimate association with the palladium. The study of the Pd-H system in this laboratory has been extended in other directions and the results will be reported soon. 

Samples were characterized by X-ray diffraction, magnetic susceptibility and chemical analysis with some results summarized in Table 1. The electrical resistivity measurements were made down to 80 K using a four-probe method. Raman scattering experiments used the excitation line A = 514.5 nm of an Ar+ laser in a quasi-backscattering geometry. The laser power of 5 mW was focused to a 0.1 mm diameter spot on the (010) surface. The averaged laser power density amounts to 6 105 W/m2 which is much less compared to earlier Raman studies in manganites [12-15],... 

Susceptance — In alternating current (AC) electrical - immittance measurements, susceptance is the imaginary part of admittance given by ... 

The methods by which the phenomenon of interconfiguration fluctuations may be studied are (i) determination of lattice constant, (ii) magnetic susceptibility measurements, (iii) Mossbauer spectroscopy, (iv) measurement of electrical resistivity, (v) Hall effect, (vi) X-ray absorption spectroscopy and (vii) X-ray photoelectron emission spectroscopy. It is useful to note that a suite of techniques must be used to detect ICF phenomenon in a system. Nuclear magnetic resonance is sparingly used because not all the systems exhibiting ICF contain magnetically active nuclei. 

A measurement of the optical conductivity of PAni samples over the range 2 meV to leV is illustrated in Fig. 9.38. The reflection spectra were obtained using a Fourier transform interferometer and a synchrotron radiation source. The Kramers-Kroiiig transformation, with appropriate extrapolation of the data to zero and high energy, was used to extract the complex frequency-dependent conductivity and its real part, the optical conductivity. The optical conductivity is related to the imaginary component of the electric susceptibility, since the power dissipated by an optical field of amplitude E is given by ... 

The tensor elements of x can be determined from measurements of macroscopic magnetic susceptibility or evaluated from molecular orbital methods and approximate variation perturbation calculations. Recently, calculations of the magnetic quadrupole polarizability of closed-shell atoms, and magneto-electric susceptibilities of atoms, have been made. These matters, which relate to the behaviour of microsystems under the simultaneous action of an electric and a magnetic field, will be dealt with in detml in subsequent sections. 

Figures 13 and 14 show the crystal structure and the temperature dependence of electrical conductivity measured along the one-dimensional axis, fc-axis, of TTF-TCNQ [53]. The conductivity increases with decreasing temperature down to about 60 K below which the conductivity is characterized by thermally activated nature. The metallic properties are ascertained by much experimental evidence such as optical reflectivity, spin-magnetic susceptibility, and thermopower [54]. In the insulating state similar measurements also suggest the presence of a band gap at the Fermi level. These measurements suggest the metal-insulator transition to oceur at 53 K.

When the macroscopic third-order electric susceptibility x jkl is measured in the laboratory (the subscripts /, J, K, L refering to the axes in the laboratory-fixed coordinate system), it is first related to the microscopic third-order coefficients [19] ... 

As shown above, there is a well-defined relationship between refractive index and electric susceptibility. According to Eq. (4.24), the refractive index is a measure of the degree of induced polarization in a given medium. We have to admit, however, in the case of an anisotropic medium that the derivation of the relationship between refractive index, dielectric constant, and permeability is very complex and a nuisance because eri and / n are tensors, and the refractive index is different for each direction of the propagated light. 

Although for p-azoxyanisole (PAA) a number of measurements in electric fields have been reported (I, 5), only Foex ( ) reported measurements in a high magnetic field. In this paper we report the results of magnetic susceptibility measurements on PAA, which have been obtained by using the Faraday method with a sensitive balance described by Poulis et al. (6). The sample consisted of 0.2841 gram of PAA held in an evacuated spherical quartz container. Measurements were made at fields of 2550, 1050, 275, and 200 oersteds at a number of temperatures in the liquid crystal and liquid phase. The absolute accuracy of the susceptibility measurements was about 3%, determined by the irreproducibility in the adjustment of... 

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