Paramagnetic susceptibilities, measurement

As a result of the paramagnetic nature of superoxides, it is possible to determine their punty by means of paramagnetic susceptibility measurements. The use of this method is limited by its poor accuracy. 

Figure 1. The number N of moles polymer per 1000 g liquid sulfur. The line is calculated from theory with parameter values as noted in the text. O, data from paramagnetic susceptibility measurements , data from ESR measurements . +, data from ESR measurements .

An ESR experiment " is a direct measurement of the quantity N. Just as in the case of the paramagnetic susceptibility measurements in 15.2.2.2.5, no parameters have to be adapted. The number of spins (twice the number of chain molecules) can be calculated from the surface area of the resonance peak. The measurements call for a careful approach insofar as the quotient of this surface area and the number of spins has to be calibrated using a reference sample with a known number of spins. Apart from this, the ESR measured linewidth could give information about the reaction rate of ... 

The magnetic moment magnitude of the free ions in units of Bohr magnetons is given by g[/(/+ l)] - For paramagnetic lanthanide ions occurring in the tripositive state in solids this quantity should be equal to the effective moment Peft obtainable from paramagnetic susceptibility measurements if the ions occur as free ions. Table 14.1 summarizes some of the most important ionic properties of the free tripositive lanthanide ions. 

Information relevant to the electronic configuration can be obtained from atomic emission spectroscopy, x-ray photoelectron spectroscopy, paramagnetic susceptibility measurements, electron paramagnetic resonance, electronic transition spectroscopy, crystal structure data, and atomic-beam experiments. Discussions of the theoretical and experimental aspects of atomic spectroscopy, magnetic properties, crystal structures of solids, and electronic absorption spectroscopy are to be found in the later chapters of this work. 

---