nuclear electric quadrupole moment

symbol: $eQ$
synonym: quadrupole moment of a nucleus
https://doi.org/10.1351/goldbook.08382
Parameter that describes the effective shape of the ellipsoid of nuclear charge distribution.
Notes:
  1. Non-zero quadrupole moment indicates that the charge distribution is not spherically symmetric.
  2. By convention, the value of \(eQ\) is taken to be positive if the ellipsoid is prolate and negative if it is oblate.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 697 (https://doi.org/10.1515/pac-2019-0203)