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The angular distribution of Auger electrons emitted in the decay of molecular iC-shell vacancies created by photoabsorption is predicted to be a direct probe of the anisotropy of molecular photoabsorption. The cr -*-n discrete absorption and the cr -*• cr /-wave shape resonance in N 2 and CO are given as examples.PACS numbers: 33.80.Eh Atomic #-shell vacancies are isotropic and hence electrons emitted by Auger decay of such vacancies have an isotropic angular distribution. 1 " 4 Molecules are different, however, for two reasons. First, molecular photoabsorption is highly anisotropic, both in the discrete, because excited states have definite symmetries but generally different energies, and in the continuum, where shape resonances can enhance photoabsorption along characteristic directions of the molecule. 5 " 9 As a result, molecular photoabsorption produces neutral-molecular excited states with definite, characteristic orientations and shape-resonant photoionization produces molecular ions with energy-dependent orientations characteristic of each resonance. Second, subsequent decay of the K-shell vacancy is a fast process compared with molecular rotation, so that the orientation of the molecular excited state/ ion will be reflected in the angular distribution of the emitted Auger electrons. For example, in , CO and N 2 there is a very intense discrete absorption of 7r symmetry about 1 Ry below the K-shell ionization threshold and a broad a-symmetry shape resonance centered about 1 Ry above threshold. 6 ' 7 ' 10 The photoabsorption to the 77 excited states preferentially creates excited molecules perpendicular to the electric vector of the light while photoionization within the a shape resonance yields molecular ions preferentially parallel. The angular distribution of a particular Auger electron will mirror these alternative orientations as one scans through the photoabsorption spectrum, Thus, molecular Auger-electron angular distributions, as a function of photoexcitation energy, provide us with a spectroscopy of the anisotropy of molecular photoabsorption. This spectroscopy permits an identification of the symmetry of discrete excited states as well as a symmetry decomposition of continuum states c For randomly oriented molecules in the gas phase, the molecular orientation induced by photoabsorption is given by Eq 0 (13) of Ref. 11 asin terms of the azimuthal and polar angles Q, m = (0 m ,

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