Field cooling modes

The X versus T and /T versus T plots at 0.01 T in the zero-field-cooled (ZFC) mode are given in Fig. 5.15. The X -T plot is slightly curved over the wide temperature range (see the inset), but generally obeys the Curie-Weiss law. The effective magnetic moment and the paramagnetic Curie temperature Op evaluated for 10-70 K range are 2.54(2. /... 

In SG-state experiments with T -c Tg, the main interest concerns the position of the resonance signal as a function of field and frequency. The prototype of this class of experiments was performed by Monod and Berthier (1980) who found that the resonance frequency depends linearly on the external field, i.e. 0 =y aH + where H is the applied static field and the constant 1. For zero-field cooled samples a 0.5, while for those cooled in large fields a 1. The additional field Tfc is a property of the system and represents an anisotropy field. Similar observations have been reported by Schultz et al. (1980) who found in addition a second resonance mode. They proposed a rather unconventional form of the anisotropy energy. Later on Fert and Levy (1980) proposed a three-site Dzyaloshinsky-Moriya mechanism to explain these results, while S.E. Barnes (1981b) pointed out that the observed EPR modes in Cu Mn alloys can be described using an Edwards-Anderson-type theory for spin glasses including an anisotropy term. 

In addition to packed catalyst bed, a fluidized bed irradiated by single and multi-mode microwave field, respectively, was also modeled by Roussy et al. [120]. It was proved that the equality of solid and gas temperatures could be accepted in the stationary state and during cooling in a single-mode system. The single-mode cavity eliminates the influence of particle movements on the electric field distribution. When the bed was irradiated in the multimode cavity, the model has failed. Never-... 

The helium gas in the trap not only helps in trapping the ions but also cools them (i.e., the kinetic energy of a trapped ion is dissipated through repeated collisions with the He gas), thus forcing the ions to the center of the trap where the quadrupole field is best defined. Both sensitivity and mass resolution are significantly enhanced by the presence of the He gas. Moreover, the same He can also be used to induce fragmentation when working in the MS" mode (see below). 

The vibrational spectrum of benzene around 1000 cnf has also been measured. IQ. Benzene was physisorbed on a cooled copper substrate in the vacuum chamber. Figure 19 shows the transmission for several thicknesses of benzene and a prism separation of 3 cm. The thickness was determined from the measured transmission in transparent regions using Eg. (7). The solid curves were calculated from Eqs. (5) and (6) using optical constants for benzene obtained from an ordinary transmission experiment.il The benzene film was assumed to be isotropic. Of the two absorption lines seen, one belongs to an in-plane vibrational mode, and one to an out-of-plane vibration. Since the electric field of the SEW is primarily perpendicular to the surface, the benzene molecules are clearly not all parallel or all perpendicular to the copper surface. Also it should be noted that the frequencies are the same (within the experimental resolution) as those of solid benzene22 and of nearly the same width. These features indicate that the benzene interacts only weakly with the copper surface, as would be expected for physisorbed molecules. 

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