Synthesis, Characterization and Photo-Physical Properties of Europium(III) and Terbium(III) Complexes with Thiosemicarbazones

Europium(III) and Terbium(III) complexes of type [Eu(L)Cl(H2O)2] and [Tb(L)OAc(H2O)2] (H2L = thiosemicarbazone ligands derived from substituted thiosemicarbazide and benzil/diacetyl) were synthesized. The ligands and synthesized complexes were characterized on the basis of elemental analysis, FT-IR and 1H NMR and X-ray diffraction studies. Photo-physical properties such as excitation spectra, emission spectra and luminescence curves of complexes were investigated. The most intense peak of Eu3+ ion found at 618 nm attributed to 5D0 → 7F2 transition and peak of Tb3+ ion at 549 nm attributed to 5D4 →7F5 transition.

ANÁLISE TERMOLUMINESCENTE DE COMPÓSITOS DE CaSO4 ATIVADO COM TERRAS RARAS

Since the thermoluminescence started to be applied to the dosimetry of ionizing radiation in 1940 different materials detectors have been proposed, and one of the most common is CaSO4. The motivation of this work was to produce crystals of CaSO4 doped with rare earth elements such as europium (Eu), neodymium (Nd) and thulium (Tm). It was also produced crystals of CaSO4:Ag. The interest in the production of these materials was to investigate other methods of production of thermoluminescent materials. The results show that the CaSO4:Tm is more suitable for use in the thermoluminescent dosimetry. Although not the most intense peak, the peak at 170 °C could be a dosimetric peak. Analyses showed that all samples have a TL response proportional to the dose absorbed.

High Peak Density Artifacts in Fourier Transform Mass Spectra and their Effects on Data Analysis

Fourier-transform mass spectrometry (FT-MS) allows for the high-throughput and high-resolution detection of thousands of metabolites. Observed spectral features (peaks) that are not isotopologues do not directly correspond to known compounds and cannot be placed into existing metabolic networks. Spectral artifacts account for many of these unidentified peaks, and misassignments made to these artifact peaks can create large interpretative errors. Without accurate identification of artifactual features and correct assignment of real features, discerning their roles within living systems is effectively impossible.We have observed three types of artifacts unique to FT-MS that often result in regions of abnormally high peak density (HPD), which we collectively refer to as HPD artifacts: i) fuzzy sites representing small regions of m/z space with a ‘fuzzy’ appearance due to the extremely high number of peaks present; ii) ringing due to a very intense peak producing side bands of decreasing intensity that are symmetrically distributed around the main peak; and iii) partial ringing where only a subset of the side bands are observed for an intense peak. Fuzzy sites and partial ringing appear to be novel artifacts previously unreported in the literature and we hypothesize that all three artifact types derive from Fourier transformation-based issues. In some spectra, these artifacts account for roughly a third of the peaks present in the given spectrum. We have developed a set of tools to detect these artifacts and approaches to mitigate their effects on downstream analyses.

Synthesis, Characterization and Novel Photoluminescence of SrWO4:Ln3+ Nanocrystals

SrWO4:Ln3+ (Ln = Eu, Ce, and Tb) nanocrystals were successfully synthesized by a hydrothermal method, and were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The results indicated that the crystalline size of nanocrystals decreases with increasing Eu3+ concentrations and increases with increasing annealing temperature, gradually. The photoluminescence properties of SrWO4:Ln3+ were investigated in detail. In the emission spectra of SrWO4:Eu3+, the luminescence was dominated by 5D0 → 7F2 transition, indicating that Eu3+ occupied a site lacking inversion symmetry. The concentration quenching effect hardly occurs. In the excitation spectra of SrWO4:Eu3+ nanocrystals monitored at 619 nm, the most intense peak is centered at 467 nm when the Eu3+ concentration was less than 10%, while the most intense peak is centered at 396 nm when the Eu3+ concentration was 15%. In the normalized emission spectra of SrWO4:Ce3+/Tb3+ nanocrystals excited at 254 nm, the intensity ratio of the sharp emission peaks from Tb3+ ions to the broad emission band from Ce3+ ions increased with increasing Tb3+ concentration.

The UV and IR Comparative Spectrophotometric Study of Some Saturated and Lacunary Polyoxometalates

Objectives: The polyoxometalates are a class of inorganic compounds with controllable shapes and sizes, and with excellent properties that make them attractive for various applications. This study is aimed at the comparative UV and IR spectra of Keggin type polyoxometalates. Methods: Compounds under (UV and IR) investigations were divided into several groups to highlight similarities between compounds or classes of compounds for the same category. There are four types of saturated Keggin structures and six lacunar compounds included in this study. The study begins with the UV investigations on aqueous solutions with 10-5 M concentration for these compounds. IR spectra were recorded as KBr pressed pellets. Results: The UV spectras presents large strong peaks between 185-195 nm corresponding to W = Od bonds, between 251-268 nm for W-O-W bridge bonds, depending on heteroatom types (As, Sb). The unsaturated cryptand ligand having Co2+ coordinated presents the most intense peak, due to the involvement of oxygen atoms from terminal W = Od coordinative bonds with high electronic densities in coordination of W-O-Co bond. The IR spectra present many peaks that are associated as follows: for terminal bonds W = Od, 955-970 cm-1; for W-OW bridging bonds, 790-910 cm-1; for W-O-As/Sb bonds to heteroatom, 690-760 cm-1. Vibrations of the bonds between heteroatoms and oxygen (As/Sb-O) appear around 620-660 cm-1. Conclusions: Similarities appear from the recorded spectra, between compounds of the same class, by category association. Very fine displacements of peaks that occur explain the influence of heteroatoms, addenda atoms or coordinated cations.

Where the Music Takes Me

The author tells her experience at performing at the memorial services of a man who shot and killed two others before killing himself. She describes how her many years of working as music therapist with psychiatric patients, using clinical improvisation and through her study of the Bonny Method of Guided and Imagery prepared both professionally and personally for this experience. She also reflects on her development and as a singer and explores her identity as a singer and how it is intertwined with her identity as a music therapist. During her performance at the memorial services she has, what she describes, as an intense peak experience and describes it as similar to Helen Bonny's peak experience she had during a violin performance. She further describes her experience as becoming one with the music and recounts how the music served as a therapeutic container for the entire memorial service and how trusting where the music was leading was a powerful and humbling experience.

Initial Stage Oxidation of Cr in Dry and Wet Environment at 1073 K and the Significant Differences of FT – IR Spectra Produced Thereof

Little information has been known on the initial – stage oxidation if there is water vapor involved. Cr samples of 10 mm × 10 mm × 1 mm were isothermally oxidized in dry and wet environment respectively for 86.4 ks. Compact and even surface of Cr2O3 was formed on samples oxidized in dry environment. However, the ability to form compact and even Cr2O3 was retarded in wet environment. XRD analysis on all samples shows that Cr2O3 can be formed in dry and wet environment. The IR transmission spectra for samples oxidized in dry environment, were consisting of more intense peak while samples oxidized in wet environment has more relaxed peak. Moreover the peak of samples oxidized in dry tends to be narrower, while samples oxidized in wet tend to have broader peak.