Neutron inelastic magnetic

Deenadas et al. (69) reported the heat capacity of NdAl2. This shows superimposition of a Schottky-type heat capacity excess over the normal X-type anomaly. Magnetization measurements (6S) on single crystals of NdAl2 in three crystallographic directions in fields up to 350kG and neutron inelastic scattering experiments (70) yielded consistent crystal field parameters (A (r4) = 40K and A (r6> = - 12K). 

This chapter treats principally the vibrational spectra determined by infrared and Raman spectroscopy. The means used to assign infrared absorption bands are outlined. Also, the rationale for the selection of permitted absorption bands is described. The basis for the powerful technique of Fourier Transform Infrared (FTIR) is presented in Appendix 6A. Polyethylene is used to illustrate both band assignment and the application of selection rules because its simple chain structure and its commercial importance have made polyethylene the most thoroughly studied polymer. The techniques of nuclear magnetic resonance, neutron inelastic scattering and ultraviolet spectroscopy are briefly described. The areas of dielectric loss and dynamic mechanical loss are not presented in this chapter, but material on these techniques can be found in Chapters 5. 

Fig. 35. Inelastic magnetic neutron spectrum of CeSnj obtained on D7 with o = 3.5mcV at a scattering angle of 20° and at T = 300 K (phonons are already subtracted using an appropriate, scaled LaSuj spectrum). The solid line is a fit with one broad quasielastic line of Lorentzian shape. Corrections due to the Q-variation of the intensity arc contained in the fitted curve, not in the data points (Holland-Moritz et al. 1982).

The values of the 5 coefficient can be derived from experimental data obtained from the magnetic susceptibility, the Schottky specific heat, the hy-perfine structure, the magnetic form factor and the neutron inelastic scattering measurements. The S " values are shown in table 15. It can be seen that the coefficient is dominant since the others are smaller by an order of magnitude. 

The review by Buyers and Holden (1985) discusses at length the neutron inelastic experiments performed on UN, UAs, USb, US, and UTe. We shall recapitulate and then review the work that has been done since the chapter by Buyers and Holden. Table 1 gives details of the actinide NaCl structure compounds that have been examined in single crystal form with inelastic neutron scattering. More details of the magnetic structure, etc., may be found in the literature (Rossat-Mignod et al. 1984, Burlet et al. 1986, 1988, Lander 1993). 

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