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Abstract: XPS spectra of silver excited by synchrotron irradiation with energy same as Al Kα X-ray has been measured. After filtering spectrum noise, the inelastic background starting from the lower binding energy of photoelectrons is removed by an iteration procedure. The energy loss spectrum for a single sub-shell photoelectron is then extracted from the Ag 3p XPS spectrum. Based on this single sub-shell photoelectron energy loss spectrum the effective energy loss function (EELF) is obtained by the extended Landau approach. Monte Carlo simulation with the derived EELF can reproduce well the experimental XPS spectrum. [Copyright &y& Elsevier]

Three nanostructured (nanocrystals, nanotubes and nanorod) Eu:TiO2 samples synthesized by a sol–gel method with chemical treating are measured by TEM and photoluminescence spectroscopy. The photoluminescence intensity of Eu:TiO2 nanotubes is the strongest among the three nanostructured samples and is clearly visible by naked eyes, which is about five times of that of Eu:TiO2 nanocrystals. The emission mechanism is proposed in this article. [Copyright &y& Elsevier]

Abstract: Pressure-induced changes on fluorescence spectra of Congo red molecules were examined up to 8.7GPa using a diamond anvil cell at room temperature. The spectra changes are demonstrated to be sensitive to the pressure and solvent conditions. At hydrostatic pressure and with a solvent used as a pressure transmitting medium the fluorescence spectra show increase of intensity with elevated pressure up to about 2.3GPa and then drop at higher pressures. For Congo red crystal under quasi-hydrostatic condition without solvent the fluorescence intensity decreases monotonically and the lower energy band becomes dominant with the pressure increasing. The three vibronic bands show red shifts with increase of pressure. [Copyright &y& Elsevier]

Abstract: Photoluminescence and Raman spectra of rare earth complex Nd(DBM)3·Phen (DBM, dibenzoylmethane; Phen, 1,10-phenanthroline) are measured at high pressures. A new Raman band appearing at 1070cm−1 indicates a second-order phase transition around 5.0GPa. Although the crystal lattice is destroyed for pressures higher than 7.1GPa, photoluminescence spectra show that the emission intensity of Nd3+ is enhanced dramatically with the pressure increasing up to 9.9GPa, which is attributed to an efficient intramolecular energy transfer from the ligand to Nd3+. By analyzing the energy of the ground and excited states at 9.9GPa, the 4H11/2 energy level is considered as the main resonance energy level that efficiently accepts the transferred energy from the ligand. [Copyright &y& Elsevier]

Abstract: The surface excitation effect is investigated by using the quantum mechanical frame work of complex self-energy of electrons which interact with a bounded semi-infinite medium. In the self-energy formalism, differential inverse inelastic mean free path (DIIMFP) has contributions from bulk and surface plasmons. Monte Carlo simulation of the interaction of electrons with a solid medium and surface has been performed. The surface excitation parameter (SEP) is then obtained from the simulated reflection electron energy loss spectroscopy (REELS) spectra. The calculated SEP results by Monte Carlo simulation are compared with the previous calculations of total surface excitation probability, which was estimated by a numerical integration of surface term of DIIMFP. The contribution merely due to surface excitations towards REELS spectra is extracted by subtracting the two Monte Carlo simulated REELS spectra that based on the two models of electron inelastic scattering, i.e. a full surface model (SM) and a pure bulk model (BM). The surface excitations found to be significant at low energy losses and diminish at higher energy losses whereas the bulk plasmon contributions show opposite behavior and are negligible at lower energy losses. The average number of surface excitations is then evaluated by the computation of ratio of the integrated surface contribution to the elastic peak. The calculated results for Ag are found to be reasonably in agreement with our previous results for total probability of surface excitations and other reported experimental data for SEP. Surface correction factor (SCF) is calculated using SEP for several metals and is compared with the reported ratio of SCF with Ni sample as reference. [Copyright &y& Elsevier]

Abstract: The sample of Eu3+-doped TiO2 (Eu3+/TiO2) nanocrystals is synthesized by the sol–gel method with hydrothermal treatment. Raman and photoluminescence (PL) spectra of the sample have been investigated under high pressure up to 18GPa using a diamond anvil cell. At ambient pressure, a strong PL signal associated with the 5D0→7FJ (J=0,1,2,3,4) transition of Eu3+ under the excitation wavelength at 514.5nm is observed. The emission peaks red shift slightly and the intensity decreases with the increase of pressure, while the intensity ratio between 5D0→7F2 and 5D0→7F1 decreases dramatically. A phase transition is observed at 8.2–10.6GPa by the Raman spectra analysis. Reducing of the intensity ratio between 5D0→7F2 and 5D0→7F1 value indicates the rising of the site symmetry and the weakening of the covalency of Eu–O bond. [Copyright &y& Elsevier]

Abstract: The pressure effect on photoluminescence (PL) and Raman spectra of the poly (para-phenylene vinylene) (PPV) has been investigated with a diamond anvil cell (DAC) under the hydrostatic pressure condition. The intensity ratios, I 1167/I 1622 and I 1543/I 1622, increase with pressure. This indicates that the conjugated length of PPV is enhanced at high pressures. In addition, appearance of a new Raman band corresponding to CC stretch at 1190cm−1 shows that the chain conformation defects decreased with increasing pressure. The redshift of the PL spectra and shift to higher frequencies for Raman bands with increase in pressure are explained by combining the conjugation model with amplitude mode model. [Copyright &y& Elsevier]