We report a detailed experimental and theoretical study on high-order harmonic generation of a femtosecond Ti-sapphire laser focused at an intensity of around 1015 W cm−2 onto a high-pressure (50–210 mbar) neon gas cell of variable length (1–3 mm). Using thorough three-dimensional simulations, we discuss the interplay between the different factors influencing the harmonic-generation efficiency, i.e. phase matching determined by the electronic and atomic dispersions, re-absorption of the harmonics by the medium and refraction of the generating laser beam. Generically, we find that, in our generation conditions, the emission yield of harmonics from the plateau region of the spectrum is absorption limited, whereas the emission from harmonics in the cut-off is strongly reduced due to both electron dispersion and ionization-induced refraction of the laser beam. A good agreement between the numerical results and the experimental data is obtained for the harmonic yield dependence on the various generation parameters (gas pressure, medium length and laser intensity).

X-ray absorption spectroscopy stud ies of the [MnIllGCrlll)1' single-mo lecu le magnet deposited as a microcrystalline layer on go ld substrates are presented. The oxidation state of the manganese cente rs cha nges from Mnlll to Mn" due to irradiatio n with soft X-rays. The influence of the charge-neutralizing anions on the stability of [MnIll 6Crlll)1' aga inst soft X-ray exposure is investigated for the different a nions tetraphenylborate (BPh 4-), lactate (C3HS0 3-) and perchlorate «(10 4-), The exposure d e pendence of the radiation-induced reduction process is compared for [MnIllGCrlll)1' with the three different anions.

Properties of the manganese-based single-molecule magnet [Mn(6)(III)Cr(III)](3+) are studied. It contains six Mn(III) ions arranged in two bowl-shaped trinuclear triplesalen building blocks linked by a hexacyanochromate and exhibits a large spin ground state of S(t) = 21/2. The dominant structures in the electron emission spectra of [Mn(6)(III)Cr(III)](3+) resonantly excited at the L(3)-edge are the L(3)M(2, 3)M(2, 3), L(3)M(2, 3)V and L(3)VV Auger emission groups following the decay of the primary p(3/2) core hole state. Significant differences of the Auger spectra from intact and degraded [Mn(6)(III)Cr(III)](3+) show up. First measurements of the electron spin polarization in the L(3)M(2, 3)V and L(3)VV Auger emission peaks from the manganese constituents in [Mn(6)(III)Cr(III)](3+) resonantly excited at the L(3)-edge near 640 eV by circularly polarized synchrotron radiation are reported. In addition spin resolved Auger electron spectra of the reference substances MnO, Mn(2)O(3) and Mn(II)(acetate)(2)·4H(2)O are given. The applicability of spin resolved electron spectroscopy for characterizing magnetic states of constituent atoms compared to magnetic circular dichroism (MCD) is verified: the spin polarization obtained from Mn(II)(acetate)(2)·4H(2)O at room temperature in the paramagnetic state compares to the MCD asymmetry revealed for a star-shaped molecule with a Mn(4)(II)O(6) core at 5 K in an external magnetic field of 5 T.

3+ structural type adsorbed thin films prepared on Si and gold-coated glass substrates have been experimentally studied by means of spin-polarized electron spectroscopy (SPES) and X-ray magnetic circular dichroism (XMCD) at the Fe L 3,2 edge using circularly-polarized synchrotron radiation. The results are cross-compared to the corresponding data obtained from the recently published measurements with Mn-based SMM [1], also in terms of the local spin and orbital magnetic moments obtained. Furthermore, [Fe III 6 Cr III ] 3+ single crystals have been experimentally studied by means of magnetometry and X-ray diffraction.

a b s t r a c t Single-molecule magnets (SMM) of the [Mn III 6 Cr III ] 3+ structural type prepared on Si and gold-coated glass substrates have been investigated by spin-resolved electron spectroscopy (SPES) and X-ray magnetic circular dichroism (XMCD) at the Mn L 3,2 edge and in addition by XMCD at the Cr L 3,2 edge using synchrotron radiation. Differences between the two methods are discussed. Despite its severe limitations for 3d transition metals, a spin sum rule evaluation is nevertheless performed for the Mn III centres in the [Mn III 6 Cr III ] 3+ SMM to provide a simple means of comparing XMCD and spin-resolved electron spectroscopy results.