  The first X-ray magnetic circular dichroism (XMCD) spectra on the title
compounds are presented. In Mn12 the Mn(III) and Mn(IV) contributions are
clearly apparent and evidence the opposite spin arrangement of the two ions.
For Fe8 the typical two peak structure of Fe(III) compounds is found.
Quantitative analysis yielded for both compounds a negligible <Lz>. This is the
first direct experimental evidence of the quenching of the angular momentum in
these systems. For Fe8 we found <Sz>=1.14 in mB units per Fe atom, in
reasonable agreement with the S=10 ground state assumed for in this system.
