Nickolaus A. Smith

An ionic liquid-mediated route to cerium(III) bromide solvates.

A novel synthetic route to a series of cerium bromide solvates is reported. The combination of bulk cerium bromide and the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide results in a precursor paste that enhances the solubility of the cerium(III)bromide moiety in a number of donor solvents. Crystallization from these solvents has resulted in the isolation and characterization of CeBr(3)(THF)(4) (2), CeBr(3)(2-Me-THF)(4) (3), and CeBr(3)(MeCN)(5)·MeCN (4). Additionally, 2 is shown to be an efficient precursor for the new species CeBr(3)(py)(4) (5) and CeBr(3)(bipy)(py)(3) (6).

Light yield measurement method for milled nanosize inorganic crystals

Composite scintillators consisting of nanosize inorganic crystals embedded in an organic matrix have been actively pursued in recent years. One method of producing nanosize crystals is through wet milling; however, since milling is known to introduce defects, the light yield of the milled crystals must be characterized. In this work, a new method of characterizing the light yield of milled inorganic crystals will be explored and discussed; this method will take into account explicitly the concentration of the inorganic crystals and the difference in stopping power between the crystals and the solvent.

Light yield measurements of milled BaFCl:Eu inorganic crystals

In recent years, composite scintillators consisting of nanosize inorganic crystals in an organic matrix have been actively developed. Ideally these scintillators would have efficiency and resolution similar to inorganic crystals, but at the same time would be inexpensive and easy to manufacture. In order to make composite scintillators optically transparent, McKigney et al. finds that nanosize inorganic crystals should be used in order to reduce optical scattering. One way to produce these nanosize inorganic crystals is through wet milling, where inorganic crystals are ground with microsize beads in an organic solvent to achieve size reduction. Milling is relatively simple in terms of preparation and equipment; however, milling is also known to introduce defects into the ground material. Therefore, a new light yield measurement technique is developed to evaluate the degree to which milling alters the light yield of the milled inorganic crystals. In this work, the light yield measurement technique is applied to samples containing BaFCl:Eu inorganic crystals milled in a tributyl phosphate (TBP) and cyclohexane mixture.

Reduced dimensionality effects on phonon transport

Electron paramagnetic resonance (EPR) spectroscopy has been used to study energy transport properties of both bulk and nanophosphor (nominally 30 nm) oxyorthosilicate samples, and we were able to separate the effects of crystal disorder and relaxation lifetime broadening on the EPR linewidths. The low temperature linewidths (T<10 K) were inhomogeneously broadened and dominated by crystal disorder effects and the nanophosphors showed an order of magnitude increase in crystal disorder. Both bulk and nanophosphor samples showed significant lifetime broadening involving direct relaxation via phonons and the Orbach relaxation process. At low temperatures, the lifetimes of the bulk samples displayed the influence of the lattice-bath relaxation time as well as the spin-lattice relaxation time while the lifetimes of the nanophosphor samples were not influenced by the lattice-bath relaxation time. The results imply that reduced dimensionality in insulators does reduce the lattice-bath relaxation time, although the...