Helium magnetic susceptibility

The quadrupole effects mentioned in Section I.B.(l) apparently are small, as magnetic susceptibility measurements18 have revealed that the energy differences between different orientations of an oxygen molecule in a /3-hydroquinone cavity become only noticeable at liquid helium temperatures. 

Microwave absorption measurements were made with a Bruker ER300 ESR spectrometer operated with 100 kHz magnetic field modulation where the derivative of the absorption part of the magnetic susceptibility with respect to magnetic field was detected (dx VdH). Temperature was varied with an Oxford Instruments ESR 900 helium flow system from room temperature to about 6 K. The temperature at the sample position in the flow dewar was calibrated with a separate thermocouple and found to be 2-3 K higher than the Instrumental... 

TABLE 2. Experimental Data for the Molar Magnetic Susceptibility of Glassy Arsenic Chalcogenides Obtained in a Helium Atmosphere... 

In this paper we modify and extend this approach in several ways. In particular, we consider the magnetic fine structure effects in the presence of a uniform electric field F for ls2p Pj- excited states of helium. We introduce two separate differential polarizabihties to describe the quadratic part of the electric field splitting and three differential hyperpolarizabilities to describe the terms the order of in the fine-structure splitting of the atomic multiplet s2p Pj. We have developed a calculational approach that allows correct estimation of potential contributions due to continuum spectra to the dipole susceptibilities j3 and 7. In the next section we briefly outline our method. The details of the calculations of the angular and radial matrix elements have been described elsewhere [8,9] and are omitted here for brevity. Atomic units are used throughout. 

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