Experimental Spectra and Their Analysis

EXPERIMENTAL SPECTRA AND THEIR ANALYSIS A. Single-Crystal Spectra 

We shall first consider the nature of the ESR spectra expected from single crystals in which the individual ions are far enough apart to make the 

A very common situation encountered is axial symmetry where gz=g and gx=gy=g - The spin Hamiltonian for axial symmetry has been solved for S=i in Appendix D, giving 

To understand how the value of g and g are obtained from the experimental spectra, we shall consider their determination for Ti3+ in a single crystal of aluminium (III) acetylacetonate. This crystal is monoclinic with two molecules per unit cell. The trigonal axes of the two molecules in the unit cell point in different directions, and thus in general two absorption lines will be seen. In Fig. 6 are shown the orientations of the appropriate 

Thus for orientation I, the maximum value of g2 occurs at cp = ft ifg g , and the minimum value of g2 is g. Such a plot is given in Fig. 7. In orientation II the rotation axis is in the ac plane at an angle p + 90° from the c axis. 

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