The dielectric functions of Cu 2 ZnGeS 4 bulk crystals grown by the Bridgman method were measured over the energy range 1.4 to 4.7 eV at room temperature using variable angle spectroscopic ellipsometry. The observed structures in the dielectric functions were adjusted using the Adachi's model and attributed to interband transitions E 0 , E 1A , and E 1B at ⌫:͑000͒, N͑A͒ :2 / a͑0.5 0.5 0.5͒, and T͑Z͒ :2 / a͑0 0 0.5͒ points of the first Brillouin zone, respectively. The model parameters ͑threshold energy, strength, and broadening͒ have been determined using the simulated annealing algorithm. The decrease in the first gap, E 0 , has been attributed to a higher Ge-S hybridization. The spectral dependence of the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity were also derived.

Distinguishing the scattering contributions of isoelectronic atomic species by means of conventional x-ray-and/or electron diffraction techniques is a difficult task. Such a problem occurs when determining the crystal structure of compounds containing different types of atoms with equal number of electrons. We propose a new structural model of Cu͑In x Ga 1−x ͒ 3 Se 5 which is valid for the entire compositional range of the CuIn 3 Se 5 -CuGa 3 Se 5 solid solution. Our model is based on neutron and anomalous x-ray diffraction experiments. These complementary techniques allow the separation of scattering contributions of the isoelectronic species Cu + and Ga 3+ , contributing nearly identically in monoenergetic x-ray diffraction experiments. We have found that CuIII 3 Se 5 ͑III =In,Ga͒ in its room temperature near-equilibrium modification exhibits a modified stannite structure ͑space group I42m͒. Different occupation factors of the species involved, Cu + , In 3+ , Ga 3+ , and vacancies have been found at three different cationic positions of the structure ͑Wyckoff sites 2a, 2b, and 4d͒ depending on the composition of the compound. Significantly, Cu + does not occupy the 2b site for the In-free compound, but does for the In-containing case. Structural parameters, including lattice constants, tetragonal distortions, and occupation factors are given for samples covering the entire range of the CuIn 3 Se 5 -CuGa 3 Se 5 solid solution. At the light of the result, the denotation of Cu-poor 1:3:5 compounds as chalcopyrite-related materials is only valid in reference to their composition.

Electrical and optical properties of p-type CuFe1-xSnxO2 (x = 0.03, 0.05) delafossite-oxide J. Appl. Phys. 113, 023103 (2013) Stoichiometry dependence of resistance drift phenomena in amorphous GeSnTe phase-change alloys J. Appl. Phys. 113, 023704 (2013) Negative refraction and subwavelength imaging in a hexagonal two-dimensional annular photonic crystal J. Appl. Phys. 113, 013109 (2013) The vibrational spectrum of CaCO3 aragonite: A combined experimental and quantum-mechanical investigation J. Chem. Phys. 138, 014201 (2013) Additional information on J. Appl. Phys. The complex dielectric functions, ͑ ͒ = 1 ͑ ͒ + i 2 ͑ ͒, of CuIn 3 Se 5 and CuIn 5 Se 8 crystals with different Cu contents have been determined in the 0.8-4.7 eV photon energy range by using spectroscopic ellipsometry. The spectral dependence of the real, 1 ͑ ͒, and imaginary, 2 ͑ ͒, parts of ͑ ͒, as well as the complex refractive index, the absorption coefficient, and the normal-incidence reflectivity, has been modeled by using a modification of Adachi's model. The results are in excellent agreement with the experimental data over the entire range of photon energies. The model parameters, including the energies corresponding to the lowest direct gap, E 0 , and to higher critical points, have been determined by using the simulated annealing algorithm.

This work presents the first application of total-reflection X-ray fluorescence (TXRF) spectrometry, a new and powerful alternative analytical method, to evaluation of the bioaccumulation kinetics of gold nanorods (GNRs) in various tissues upon intravenous administration in mice. The analytical parameters for developed methodology by TXRF were evaluated by means of the parallel analysis of bovine liver certified reference material samples (BCR-185R) doped with 10 μg/g gold. The average values (n = 5) achieved for gold measurements in lyophilized tissue weight were as follows: recovery 99.7%, expanded uncertainty (k = 2) 7%, repeatability 1.7%, detection limit 112 ng/g, and quantification limit 370 ng/g. The GNR bioaccumulation kinetics was analyzed in several vital mammalian organs such as liver, spleen, brain, and lung at different times. Additionally, urine samples were analyzed to study the kinetics of elimination of the GNRs by this excretion route. The main achievement was clearly differentiating two kinds of behaviors. GNRs were quickly bioaccumulated by highly vascular filtration organs such as liver and spleen, while GNRs do not show a bioaccumulation rates in brain and lung for the period of time investigated. In parallel, urine also shows a lack of GNR accumulation. TXRF has proven to be a powerful, versatile, and precise analytical technique for the evaluation of GNRs content in biological systems and, in a more general way, for any kind of metallic nanoparticles.

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