gFactor of Conduction Electrons in Metallic Lithium

The electron spin resonance of metallic lithium particles immersed in mineral oil has been carefully examined in order to determine the $g$ shift of the conduction electrons with respect to the free-electron value. By comparing the ESR frequency with the proton nuclear-spin frequency of the mineral oil, and extending Dyson's line-shape theory to apply to intermediate-size metallic particles, the shift at room temperature was found to be $\Delta g=-2\mathrm{}\times {10}^{-6\mathrm{}}$. This small $g$ shift indicates that the inherent linewidth of the ESR in metallic lithium may well be only 4 mG in a 3000-G field. In addition, an Overhauser enhancement of over 750 was measured when the lithium NMR was monitored and the ESR saturated. The shift in the lithium NMR arising from ESR saturation demonstrated that at least 75% of the measured Knight shift is due to electron-gas paramagnetism.