We have developed an angle-resolved photoemission spectrometer with tunable vacuum ultraviolet laser as a photon source. The photon source is based on the fourth harmonic generation of a near IR beam from a Ti:sapphire laser pumped by a CW green laser and tunable between 5.3 eV and 7 eV. The most important part of the set-up is a compact, vacuum enclosed fourth harmonic generator based on potassium beryllium fluoroborate crystals, grown hydrothermally in the US. This source can deliver a photon flux of over 10(14) photon/s. We demonstrate that this energy range is sufficient to measure the k(z) dispersion in an iron arsenic high temperature superconductor, which was previously only possible at synchrotron facilities.
Structural and spectroscopic properties of rare-earth ( Nd 3+ , Er 3+ , and Yb 3+ ) doped transparent lead lanthanum zirconate titanate ceramics This work studies the spectroscopic behavior of Eu 3ϩ -doped and Yb 3ϩ /Er 3ϩ -codoped single crystals of orthorhombic LaBO 3 and rhombohedral GdBO 3 . Emissions from Er 3ϩ at ϳ1535 nm are shown to exhibit multiple narrow linewidth emissions. Luminescence from the 5 D 0 → 7 F 1 , 7 F 2 transitions of Eu 3ϩ is found to depend on the choice of LaBO 3 or GdBO 3 as a parent phase in a well-defined manner. Phonon sideband spectroscopy of the Eu 3ϩ 5 D 2 excitation, corroborated using Raman spectroscopy, indicates that the highest energy phonon is less than 1400 cm Ϫ1 for the LaBO 3 and less than 1010 cm Ϫ1 for the GdBO 3 . Further, absorption spectrum to 190 nm is provided for the GdBO 3 clearly showing the 6 I manifold, and the rarely seen 6 D levels. Excitation of the 6 D 7/2 state at 250 nm in GdBO 3 is shown to yield a strong ultraviolet emission centered at 314 nm. This work marks the lanthanide borates as candidate single crystals for active and nonlinear materials for UV, visible, and telecommunication band applications.
The title compound, calcium dimanganese tetraoxide, CaMn(2)O(4), was synthesized hydrothermally and is made up of edge-sharing Mn(3+) distorted octahedral layers and eight-coordinate Ca(2+) centered polyhedral layers.
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