The undoped and Mo-doped TiO2 nanoparticles were synthesized by sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD), diffuse reflectance UV-visible absorption spectra (UV-vis DRS), X-ray photoelectron spectra (XPS), and transmission electron microscopy (TEM). The photocatalytic activity was evaluated by photocatalytic degradation of methylene blue under irradiation of a 500&#x2009;W xenon lamp and natural solar light outdoor. Effects of calcination temperatures and Mo doping amounts on crystal phase, crystallite size, lattice distortion, and optical properties were investigated. The results showed that most of Mo6+ took the place of Ti4+ in the crystal lattice of TiO2, which inhibited the growth of crystallite size, suppressed the transformation from anatase to rutile, and led to lattice distortion of TiO2. Mo doping narrowed the band gap (from 3.05&#x2009;eV of TiO2 to 2.73&#x2009;eV of TiMo0.02O) and efficiently increased the optical absorption in visible region. Mo doping was shown to be an efficient method for degradation of methylene blue under visible light, especially under solar light. When the calcination temperature was 550&#xb0;C and the Mo doping amount was 2.0&#x25;, the Mo-doped TiO2 sample exhibited the highest photocatalytic activity.

Ji-guo Huang

Xue-ting Guo

Bo Wang

Lin-yang Li

Mei-xia Zhao

Li-li Dong

Xing-juan Liu

Yu-ting Huang

Synthesis and Photocatalytic Activity of Mo-Doped TiO2 Nanoparticles

The design and realization of grating instruments to condition the spectral phase of ultrashort extreme-ultraviolet pulses are discussed. The main application of such configurations is the temporal compression of pulses by compensating the phase chirp and getting close to the Fourier limit. We discuss the two configurations useful for the realization of ultrafast grating compressors, namely, the classical diffraction mount and the off-plane one. The configuration may be applied to free-electron lasers and high-order laser harmonics.

Fabio Frassetto

Paolo Miotti

Luca Poletto

Compression of Extreme-Ultraviolet Ultrashort Pulses by Grating Configurations

To apply the fundamental parameters method at the confocal setup the knowledge of the sensitivity of the spectrometer is required which depends on the characteristics of two X-ray lenses: one in the excitation channel and another in the detection channel. For the particular case of polychromatic excitation, the theory shows that the focalization properties of the excitation lens for all incident energies affect the X-ray fluorescence intensity. Therefore the traditional calibration method based on the measurement of standard samples becomes unstable since the number of required fitting parameters is too high. To reduce these parameters a previous characterization of the excitation lens by a simulation program was employed giving rise to a simplified confocal setup calibration. The developed calibration method was applied for a confocal spectrometer implemented in the Brazilian Synchrotron Radiation Source (LNLS) with white beam. The experimental parameters of the sensitivity were obtained from depth profile analysis of several pure thin films. The calibrated confocal setup was used to quantify reference standards in order to validate the calibration procedure. Our results for elemental concentrations show relative errors less than 15&#x25; for the quantitative analysis of a light matrix reference standard.

C. Sosa

V. Stoytschew

J. Leani

H. J. S&#xe1;nchez

C. A. P&#xe9;rez

R. D. Perez

Calibration Method for Confocal X-Ray Microanalysis with Polychromatic Excitation

Aldehydes and ketones are volatile organic compounds (VOC) emitted into the atmosphere by a large number of natural and anthropogenic sources. Carbonyl compounds (CC) are atmospheric pollutants with known damaging effects for the human&#x2019;s health. In this work, the separation of 31 carbonyl compounds (CC) in their 2,4-dinitrophenylhydrazones form was optimized by rapid resolution liquid chromatography in 9 minutes and simultaneously detected by ultraviolet and mass spectrometry with an APCI(&#x2212;) as ionization source. The mass spectra of hydrazones presented the [M-H]&#x2212; ions as base peak, but the MS/MS spectra showed fragments related to different structural classes of aldehydes and ketones, representing an important tool to assist structure elucidation of unknown CC in real samples. Multiple reactions monitoring (MRM) improved the sensitivity and selectivity for the quantitation method. Analytical parameters using both UV and MS (linearity, determination coefficients, detection limits, and sensitivity) were compared. The detection methods are complementary and a powerful analytical tool for the detection and quantitation of CC in complex environmental samples.

Soraya de M. Ochs

Ma&#xed;ra Fasciotti

Annibal D. Pereira Netto

Analysis of 31 Hydrazones of Carbonyl Compounds by RRLC-UV and RRLC-MS(/MS): A Comparison of Methods

The Raman spectrum of the indocyanine-type dye IR-820 has been assigned for both solid and solution. SERS spectra of IR-820 on both silver and gold nanoparticles suspensions excited at 1064&#x2009;nm were obtained. AgNPs allowed the detection of the dye through SERS down to 0.1 micromoles per liter; for the AuNPs the lowest concentration of the dye detectable was 10 micromoles per liter. Changes in the SERS relative intensities compared to the Raman spectrum in solution are subtle, mostly due to the preresonance effect of the dye. However, a perpendicular orientation relative to the metallic surface was inferred for the dye on both AgNPs and AuNPs. The easily distinguishable SERS spectra of the dye excited at 1064&#x2009;nm, together with the high biological compatibility of cyanine dyes, are both indicative that IR-820 could be used as a high-performance probe molecule for SERS.

Tatiana B. V. Neves

Gustavo F. S. Andrade

SERS Characterization of the Indocyanine-Type Dye IR-820 on Gold and Silver Nanoparticles in the Near Infrared

Nanostructured fluorescent pyrromethene (PM) doped-silica core-shell particles were successfully prepared by St&#xf6;ber process. The average size of the particles was in the range of 10&#x2013;20&#x2009;nm measured by TEM micrograph. The atomic structure and morphology of PM 597/SiO2 core/shell nanoparticles were studied by AFM and SEM, respectively. Absorption and emission spectra of the PM 597/SiO2 core/shell nanoparticles under the UV irradiation were studied and not significantly influenced at the position of peaks. Finally, amplified spontaneous emission (ASE) and photobleaching of dye were examined and found no significant influence on the peaks of PM dye due to the formation of smaller sizes of PM 597/SiO2 core/shell nanoparticles. The observed PM 597/SiO2 core/shell nanoparticles were different in shapes with smaller size distribution and highly luminescent. Majority of nanoparticles were roughly spherical with many of them aggregated. The less photobleaching of dye core may be due to the protection of pumped energy by SiO2 shell and restricts the leakage of dye.

Tahani R. Al-Biladi

A. S. Al Dwayyan

M. Naziruddin Khan

Saif M. H. Qaid

Khalid Al Zahrani

Structural and Spectroscopic Characterization of PM 597 Dye-Silica Core-Shell Nanoparticles

The aim of the present study was to obtain modified X-ray spectra, by using appropriate filter materials for use in applications such as dual energy X-ray imaging. K-edge filtering technique was implemented in order to obtain narrow energy bands for both dual- and single-kVp techniques. Three lanthanide filters (cerium, holmium, and ytterbium) and a filter outside lanthanides (barium), with low K-edge, were used to modify the X-ray spectra. The X-ray energies that were used in this work ranged from 60 to 100&#x2009;kVp. Relative root mean square error (RMSE) and the coefficient of variation were used for filter selection. The increasing filter thicknesses led to narrower energy bands. For the dual-kVp technique, 0.7916&#x2009;g/cm2 Ho, 0.9422&#x2009;g/cm2 Yb, and 1.0095&#x2009;g/cm2 Yb were selected for 70, 80, and 90&#x2009;kVp, respectively. For the single-kVp technique 0.5991&#x2009;g/cm2 Ce, 0.8750&#x2009;g/cm2 Ba, and 0.8654&#x2009;g/cm2 Ce were selected for 80, 90, and 100&#x2009;kVp, respectively. The filtered X-ray spectra of this work, after appropriate modification, could be used in various X-ray applications, such as dual-energy mammography, bone absorptiometry, and digital tomosynthesis.

N. Martini

V. Koukou

C. Michail

P. Sotiropoulou

N. Kalyvas

I. Kandarakis

G. Nikiforidis

G. Fountos

Pencil Beam Spectral Measurements of Ce, Ho, Yb, and Ba Powders for Potential Use in Medical Applications

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Journal of Spectroscopy publishes research into the theory and application of spectroscopy across all disciplines, including biology, chemistry, engineering, earth sciences, medicine, materials science, physics, and space science.

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Chief Editor&nbsp;Dr Daniel Cozzolino&nbsp;is based at the University of Queensland, Australia. His research focuses on the developments of chemometric and spectroscopic methods for use in agriculture and food applications.

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Journal of Spectroscopy - Table of contents 2015

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Journal of Spectroscopy publishes research into the theory and application of spectroscopy across all disciplines, including biology, chemistry, engineering, earth sciences, medicine, materials science, physics, and space science.

Journal of Spectroscopy