The first measurements of the angular distribution of Auger electrons from fixed-in-space molecules have been performed in the C $K$-shell ionization region of $\mathrm{CO}$, for both parallel and perpendicular orientations of the molecular axis with respect to the light polarization vector. The angular distributions obtained for the ${\mathrm{CO}}^{2+}{B}^1\Sigma$ Auger final state show dramatic spectral variations, which also depend on the initial ionization channels, $\Sigma$ or $\Pi$, and on the ionization photon energy. This dynamical angular correlation process strongly suggests the breakdown of a two-step model in which the Auger decay is treated independently of the initial photoionization process.

• Received 1 May 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.203001