Experimental-Determination Of The Atomic Quadrupole-Moment Of Graphite

The symmetry of the graphite crystal implies that each carbon atom has an electric quadrupole moment associated with it. This atomic moment may have a significant influence on the location of adsorbed molecules on a graphite surface and on the adsorption energy. A novel experiment, involving the measurement of the effect of a laboratory electric field gradient on the period of oscillation of a small single crystal of graphite mounted on a glass torsion fibre, has been carried out. The quadrupole moment of a carbon atom within the sample is found to be (-3.03 +/- 0.10) x 10(-40) C m2 ; however, this value may include a contribution from surface effects.