Size Dependence ofL2,3Branching Ratio and2pCore-Hole Screening in X-Ray Absorption of Metal Clusters

Abstract

Resonant 2p x-ray absorption spectra of size-selected transition metal ions and clusters consisting of 1<or=n<or=200 atoms are reported. Remnants of atomic multiplet splitting in L(2,3)-edge x-ray absorption can be resolved up to the trimer, above which the overall line shape is already bulklike. A strong cluster size dependence of the L(2,3) branching ratio was found for titanium, vanadium, and cobalt clusters. While 3d electron delocalization increases with cluster size, the apparent 2p spin-orbit splitting remains constant within the error bars. The size dependence of the L(2,3) branching ratio can be attributed to cluster size specific screening of the 2p-3d Coulomb interaction by 3d/4s valence electrons.

Magnetic properties of low-moment ferrimagnetic Heusler Cr2CoGa thin films grown by molecular beam epitaxy

“…The Cr signal was quite low due to the antiferromagnetically coupled Cr atoms, and there was a branching ratio of L 3 /L 2 = 1.53. [27][28][29] The extracted magnetic moments are plotted in Fig. 3(f), where the Co atomic moment increases by a factor of 7 between the temperatures 300-325 o C, further indicating phase segregates formed from the Heusler lattice after annealing at 325 o C. The increasing magnetic moment supports the possible XRD phase segregations with an increasing Co phase concentration.…”

Multiplet features and magnetic properties of Fe on Cu(111): From single atoms to small clusters

“…The overall values are quite high considering that the statistical ratio of L 3 :L 2 is 2:1, and crystal field and spin-orbit interaction normally cause a reduction. However, large branching ratios were observed for small Fe clusters in the gas phase and attributed to size-dependent core-hole screening [44,45].…”

Size-dependent Auger spectra and two-hole Coulomb interaction of small supported Cu-clusters

“…Core-level photoelectron spectroscopy is a surface sensitive and element specific tool which can be applied to study highly diluted samples such as free and deposited clusters by X-ray photoelectron spectroscopy (XPS), [1][2][3][4][5][6][7][8][9] X-ray absorption spectroscopy (XAS) [10][11][12] , extended X-ray absorption fine structure analysis (EXAFS), 13 grazing-incidence small-angle X-ray scattering (GISAXS), 14 X-ray magnetic circular dichroism (XMCD) [15][16][17] and Auger electron spectroscopy (AES). 18 In particular AES and XPS provide information on the initial and final states such as chemical effects, charge transfer, core-hole screening, core-hole binding energies, and electron correlation including final-state term splitting and on-site electron-electron interaction.…”