Filtyp
We present the first structural determination of the Pt2(P 2O5H2)44- anion in solution by analyzing the extended X-ray absorption fine structure (EXAFS) spectrum of the Pt LIII edge. The data could be fit with a simple model involving single and multiple scattering paths to near and far P-atoms, bridging O-atoms, and the other Pt-atom in the binuclear complex. A Pt-Pt distance of 2.876(28) Å and a
Time-resolved x-ray absorption fine structure (XAFS) spectroscopy with pico-second temporal resolution is a new method to observe electronic and geometric structures of short-lived reaction intermediates. It combines an intense femto-second laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). We present key experiments on charge transf
The ultrafast relaxation of aqueous iron(II)-tris(bipyridine) upon excitation into the singlet metal-to-ligand charge-transfer band ( 1MLCT) has been characterized by femtosecond fluorescence up-conversion and transient absorption (TA) studies. The fluorescence experiment shows a very short-lived broad 1MLCT emission band at ∼600 nm, which decays in ≤20 fs, and a weak emission at ∼660 nm, which we
The photoinduced energy and structural relaxation of aqueous iron(II)-tris-bipyridine ([FeII(bpy)3]2+), upon excitation into its singlet metal-to-ligand charge transfer (1MLCT) band, and the population of its short-lived (≤0.6 ns) high-spin excited state have been characterized by combined ultrafast optical and X-ray spectroscopies. Polychromatic femtosecond fluorescence up-conversion reveals a ve
We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy) 3
We report on the observation of the solvation shell rearrangement after abstraction of the electron from aqueous I - in a laser pump/X-ray probe experiment by recording the X-ray absorption L 1 - and L 3 -edge spectra, 50 ps after laser excitation. The L 1 -edge spectra clearly identify the I 0 neutral species after excitation and suggest a substantial amount of back-transfer of charge from the s
Structural changes of the iron(II)-tris-bipyridine ([FeII(bpy)3]2+) complex induced by ultrashort pulse excitation and population of its short-lived (0.6ns) quintet high spin state have been detected by picosecond x-ray absorption spectroscopy. The structural relaxation from the high spin to the low spin state was followed over the entire lifetime of the excited state. A combined analysis of the x
The time-dependent electronic structure of Eu:SrGa 2 S 4 after excitation by a femtosecond laser pulse is investigated by time-resolved x-ray absorption spectroscopy. We observe a transient shift in the Eu L 3 edge consistent with Eu ionization.
With ultraviolet illumination, we have found a broad UV-induced absorption in the blue and some involvement of Pr ions in Pr:LiNbO 3 . Transient and stable absorption induced by UV illumination was analyzed at 457, 514, and 633 nm and could be explained by hole trap centers and iron ions. We also studied the effects of UV illumination and boundary conditions during holographic recording in the vi
We have observed ultraviolet-induced visible absorption and performed two-color holographic recording at green, red, and near-infrared light in thulium doped near-stoichiometric LiNbO 3 crystal. The diffraction efficiency and sensitivity of the recording process at all wavelengths are increased by ultraviolet gating light. Characteristics of recording in the visible are explained by a two-center
Mn-doped AlN films were prepared by magnetron reactive sputtering system. The preparation conditions were optimized to give pure single-phase AlMnN films. The films were deposited on quartz substrates. The single-phase films were obtained in argon-nitrogen pressure of 6 mTorr and a substrate temperature of 300 °C. The films typically had a thickness of 0.4 μm. The XRD pattern indicated a pure AlM
Optical spectroscopy of Tm3+-doped 59H3BO 3-20ZnO-20LiF-1Tm2O3 glass is presented. From the measured absorption spectra, radiative parameters were determined using the Judd-Ofelt (JO) theory. Excitation in the range of 750-800 nm resulted in a frequency up-converted emission at 453 nm (1D2 → 3F4). Excitation spectra and intensity dependence of the up-converted fluorescence have been investigated a
A large magneto-caloric effect is reported in a La0.8Ca 0.2MnO3 single crystal. The magnetic entropy change (ΔSM) reaches ∼7.25 J/kg K for an applied field of 5 T, which is very practical for magnetic refrigeration applications. Satisfactory agreement between the theoretical calculations on ΔSM derived in the molecular field approximation and the experimental dependency has been found.
We report ultraviolet-induced transient and stable absorption and two-color holographic recording at 514, 633, and 830 nm in thulium doped stoichiometric LiNbO 3 crystal. The gating light at 355 nm increased the diffraction efficiency and sensitivity. We found the optimum gating-recording intensity ratio for maximum diffraction efficiency and weak nonvolatile holographic storage with gating.
We investigated the photoluminescence properties of near-stoichiometric LiNbO3 crystals doped with Tb only and double doped with Tb and Fe. Excitation spectra for the emission from the 5D4 state in both crystals have been studied in the range 200-500 nm. We observed two broad ultraviolet absorption bands and discussed their relations to Tb ions. Temperature dependence of the 5D4 emission intensity
From the ultraviolet induced absorption, we have found a broad blue band and little involvement of Pr ions in ultraviolet illumination. Ultraviolet excited photoluminescence and the excitation spectra for visible emission were also measured in Pr:LiNbO3. We estimated photovoltaic constant and photoconductivity by measuring photovoltaic current and voltage with different boundary conditions. With u
We report on the up-converted emissions at 367, 458 and 483 nm in thulium doped lutetium aluminum garnet (LuAG) under infrared excitation in the range of 730-800 nm. We also observe blue and strong green emission in thulium and holmium codoped LuAG with near infrared excitation. Excitation spectra, power dependence, temporal behavior and temperature dependence of up-converted emissions were measur
