Synthesis of CdS nanoparticles within thermally evaporated aerosol OT thin films

In this paper, we discuss the synthesis of cadmium sulfide (CdS) quantum dots within thermally evaporated sodium bis(2-ethylhexyl)sulfosuccinate (AOT) thin films. This procedure uses electrostatic interactions to entrap positively charged cadmium ions into thin films of the anionic surfactant AOT by a simple immersion of the film in electrolyte solution. Thereafter, the composite film is treated with H2S gas/Na2S solution resulting in the in-situ formation of CdS nanoparticles in the quantum size regime. It is believed that the ability of AOT molecules in the thermally evaporated thin films to form reverse micelles is responsible for the CdS nanoparticle size control observed. Investigation of the entrapment of cadmium ions in the AOT film and subsequent quantum dot synthesis was carried out by quartz crystal microgravimetry (QCM), UV-Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) measurements

IO3- and I- Sorption from Groundwater by Layered Double Hydroxides

Several subsurface water plumes are found at the Hanford U.S. DOE site. These plumes contain many different types of hazardous components including radioactive iodate (IO3-) and iodide (I-), which may have deleterious health effects. To selectively uptake IO3- and I-, inorganic layered double hydroxide (LDH) compounds were synthesized and tested. LDHs are mixed transition metal hydroxides that contain positively charged layers that undergo anion exchange. When LDHs are submerged in the plume water, they can selectively uptake IO3- and I- and remove them from the plume. Raman spectroscopy was used to monitor the uptake of IO3- and I-. The thermodynamic properties of the LDHs were determined by differential scanning calorimetry (DSC), where a phase transition was observed in the thermogram of each LDH compound. The thermodynamic properties describe the temperature range where the LDH compounds are stable and uptake the highest concentration of IO3- and I-. Raman spectroscopy indicated which LDH compounds were the most selective for IO3-. Further experiments will be performed to determine IO­3- and I- sorption of LDH compounds in groundwater. Similar technology can then be applied to radioactive waste where interferences from other compounds are present

Grandpa Bulbrook

A series of platinum­(II) complexes with the formulas Pt­(diimine)­(pip₂NCNH₂)­(L)²⁺ [pip₂NCNH₂⁺ = 2,6-bis­(piperidiniummethyl)­phenyl cation; L = Cl, Br, I, NCS, OCN, and NO₂; diimine = 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (NO₂phen), and 5,5′-ditrifluoromethyl-2,2′-bipyridine (dtfmbpy)] were prepared by the treatment of Pt­(pip₂NCN)­Cl with a silver­(I) salt followed by the addition of the diimine and halide/pseudohalide under acidic conditions. Crystallographic data as well as ¹H NMR spectra establish that the metal center is bonded to a bidentate phenanthroline and a monodentate halide/pseudohalide. The pip₂NCNH₂⁺ ligand with protonated piperidyl groups is monodentate and bonded to the platinum through the phenyl ring. Structural and spectroscopic data indicate that the halide/pseudohalide group (L^–) and the metal center in Pt­(phen)­(pip₂NCNH₂)­(L)²⁺ behave as Brønsted bases, forming intramolecular NH···L/NH···Pt interactions involving the piperidinium groups. A close examination of the 10 structures reported here reveals linear correlations between N–H···Pt/L angles and H···Pt/L distances. In most cases, the N–H bond is directed toward the Pt–L bond, thereby giving the appearance that the proton bridges the Pt and L groups. In contrast to observations for Pt­(tpy)­(pip₂NCN)⁺ (tpy = 2,2′;6′,2″-terpyridine), the electrochemical oxidation of deprotonated adducts, Pt­(diimine)­(L)­(pip₂NCN), is chemically and electrochemically irreversible

trans-K3[TcO2(CN)4]

The structure of the title compound, tripotassium trans-tetra­cyanidodioxidotechnetate(V), is isotypic with its Re analogue. The [TcO2(CN)4]3− trans-tetra­cyanido­dioxido­technetate anion has a slightly distorted octa­hedral configuration. The Tc atom is located on a center of inversion and is bound to two O atoms in axial and to four cyanide ligands in equatorial positions. The Tc—O distance is consistent with a double-bond character. The two potassium cations, one located on a center of inversion and one in a general position, reside in octa­hedral or tetra­hedral environments, respectively. K⋯O and K⋯N inter­actions occur in the 2.7877 (19)–2.8598 (15) Å range

Variable-pressure luminescence and Raman spectroscopy of molecular transition metal complexes : spectroscopic effects originating from small, reversible structural variations

The past ten years have seen a significantly increasing number of published crystal structures for molecular transition metal complexes at variable pressure, providing quantitative information on structural variations. Spectroscopic measurements at variable pressure have been reported over the past 60 years for a variety of complexes, but luminescence measurements were mostly limited to intense signals until early in this century. The combination of variable-pressure structure variations with spectroscopic trends can lead to detailed new insight on a variety of aspects of electronic structure. This approach holds promise for the in-depth study of many categories of functional materials

Spectroscopic Characterization of Aqua [ fac-Tc(CO)3]+ Complexes at High Ionic Strength.

Understanding fundamental Tc chemistry is important to both the remediation of nuclear waste and the reprocessing of nuclear fuel; however, current knowledge of the electronic structure and spectral signatures of low-valent Tc compounds significantly lags behind the remainder of the d-block elements. In particular, identification and treatment of Tc speciation in legacy nuclear waste is challenging due to the lack of reference data especially for Tc compounds in the less common oxidation states (I-VI). In an effort to establish a spectroscopic library corresponding to the relevant conditions of extremely high ionic strength typical for the legacy nuclear waste, compounds with the general formula of [ fac-Tc(CO)3(OH2)3- n(OH) n]1- n (where n = 0-3) were examined by a range of spectroscopic techniques including 99Tc/13C NMR, IR, XPS, and XAS. In the series of monomeric aqua species, stepwise hydrolysis results in the increase of the Tc metal center electron density and corresponding progressive decrease of the Tc-C bond distances, Tc electron binding energies, and carbonyl stretching frequencies in the order [ fac-Tc(CO)3(OH2)3]+ > [ fac-Tc(CO)3(OH2)2(OH)] > [ fac-Tc(CO)3(OH2)(OH)2]-. These results correlate with established trends of the 99Tc upfield chemical shift and carbonyl 13C downfield chemical shift. The lone exception is [ fac-Tc(CO)3(OH)]4 which exhibits a comparatively low electron density at the metal center attributed to the μ3-bridging nature of the -OH ligands causing less σ-donation and no π-donation. This work also reports the first observations of these compounds by XPS and [ fac-Tc(CO)3Cl3]2- by XAS. The unique and distinguishable spectral features of the aqua [ fac-Tc(CO)3]+ complexes lay the foundation for their identification in the complex aqueous matrixes

Investigations Into the Nature of Alkaline Soluble, Non-Pertechnetate Technetium

This report summarizes work accomplished in fiscal year (FY) 2013, exploring the chemistry of a low-valence technetium(I) species, [Tc(CO)3(H2O)3]+, a compound of interest due to its implication in the speciation of alkaline-soluble technetium in several Hanford tank waste supernatants. Various aspects of FY 2013’s work were sponsored both by Washington River Protection Solutions and the U.S. Department of Energy’s Office of River Protection; because of this commonality, both sponsors’ work is summarized in this report. There were three tasks in this FY 2013 study. The first task involved examining the speciation of [(CO)3Tc(H2O)3]+ in alkaline solution by 99Tc nuclear magnetic resonance spectroscopy. The second task involved the purchase and installation of a microcalorimeter suitable to study the binding affinity of [(CO)3Tc(H2O)3]+ with various inorganic and organic compounds relevant to Hanford tank wastes, although the actual measure of such binding affinities is scheduled to occur in future FYs. The third task involved examining the chemical reactivity of [(CO)3Tc(H2O)3]+ as relevant to the development of a [(CO)3Tc(H2O)3]+ spectroelectrochemical sensor based on fluorescence spectroscopy

Development of a Chemistry-Based, Predictive Method for Determining the Amount of Non-Pertechnetate Technetium in the Hanford Tanks: FY 2012 Progress Report

This report describes investigations directed toward understanding the extent of the presence of highly alkaline soluble, non-pertechnetate technetium (n-Tc) in the Hanford Tank supernatants. The goals of this report are to: a) present a review of the available literature relevant to the speciation of technetium in the Hanford tank supernatants, b) attempt to establish a chemically logical correlation between available Hanford tank measurements and the presence of supernatant soluble n-Tc, c) use existing measurement data to estimate the amount of n-Tc in the Hanford tank supernatants, and d) report on any likely, process-friendly methods to eventually sequester soluble n-Tc from Hanford tank supernatants

Spectroscopic Properties of Lanthanide (III) Compounds in Aqueous and Ionic Media

Lanthanide containing materials are receiving increasing attention due to their wide range of potential applications including bioanalytical imaging, dye-sensitized solar cells, nano-biotechnology and catalysis. The unique spectroscopic properties (intense and sharp emission bands with high color purity and high quantum efficiency) of lanthanides make them strong candidates for use as bio-markers or selective detectors. The attractiveness of lanthanides as future imaging agents as well as recent interest in their potential use in biological media has increased the need to understand the behavior of lanthanides in the presence of other ions or in ionic media. The complexity of the biological media and the diversity and variability of the ions present in it makes it important to be aware of any interactions between the lanthanide complexes and ions. The focus of this research is to add to the knowledge base on the absorption and emission behavior of various lanthanide complexes in the presence of a range of ionic media. This study is designed towards understanding the spectroscopic behavior of lanthanides in ionic environments. For the first segment of the study, absorbance spectra for solutions of lanthanide (III) nitrates in de-ionized (DI) water, and in aqueous solutions of NaCl and MgCl2 were compared and contrasted. These were complemented by measurements of emission spectra. While the presence of ions did not produce distinguishable changes in the absorbance spectra, there were significant changes in the emission intensity and emission profile of those lanthanides tested. The next step would be to measure the emission of lanthanide compounds in ionic liquids and to test a broader variety of lanthanide compounds in biological media. These results suggest that further study is warranted with consideration to the use of lanthanides as biomarkers. PNNL-SA-8203