| 1. |
- Schmidt, Daniel, et al.
(author)
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Optical properties of hybrid titanium chevron sculptured thin films coated with a semiconducting polymer
- 2011
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In: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND. - 0040-6090. ; 519:9, s. 2645-2649
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Journal article (peer-reviewed)abstract
- Optical and structural properties of a hybrid metallic chevron sculptured thin film from titanium coated with the semiconducting polymer poly(3-dodecylthiophene) (P3DDT) are reported. The nanostructured thin film with two subsequent layers of oppositely slanted nanocolumns was fabricated by glancing angle deposition and coated with P3DDT by a spin-cast process. Spectroscopic generalized ellipsometry is employed to determine geometrical structure properties and the anisotropic optical constants of the coated and uncoated film in the spectral range from 400 to 1700 nm. The nanostructured thin films before and after hybridization show highly anisotropic optical properties. The complex refractive indices along major polarizability directions of the hybridized chevrons are increased in the entire investigated spectral range with respect to the as-deposited chevrons. Changes in birefringence and dichroism upon polymer infiltration are observed.
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| 2. |
- Boosalis, Alexander, et al.
(author)
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Spectroscopic Mapping Ellipsometry of Graphene Grown on 3C SiC
- 2012
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In: MRS Proceedings Volume 1407. - : Springer Science and Business Media LLC. ; , s. aa20-43
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Conference paper (peer-reviewed)abstract
- Spectroscopic mapping ellipsometry measurements in the visible spectrum (1.25 to 5.35 eV) are performed to determine the lateral variations of epitaxial graphene properties as grown on 3C SiC. Data taken in the visible spectrum is sensitive to both the Drude absorption of free charge carriers and the characteristic exciton enhanced van Hove singularity at 5 eV. Subsequent analysis with simple oscillator models allows the determination of physical parameters such as free charge carrier scattering time and local graphene thickness with a lateral resolution of 50 microns.
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| 3. |
- Orlando, Ludovic, et al.
(author)
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Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse
- 2013
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 499:7456, s. 74-
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Journal article (peer-reviewed)abstract
- The rich fossil record of equids has made them a model for evolutionary processes(1). Here we present a 1.12-times coverage draft genome from a horse bone recovered from permafrost dated to approximately 560-780 thousand years before present (kyr BP)(2,3). Our data represent the oldest full genome sequence determined so far by almost an order of magnitude. For comparison, we sequenced the genome of a Late Pleistocene horse (43 kyr BP), and modern genomes of five domestic horse breeds (Equus ferus caballus), a Przewalski's horse (E. f. prze-walskii) and a donkey (E. asinus). Our analyses suggest that the Equus lineage giving rise to all contemporary horses, zebras and donkeys originated 4.0-4.5 million years before present (Myr BP), twice the conventionally accepted time to the most recent common ancestor of the genus Equus(4,5). We also find that horse population size fluctuated multiple times over the past 2 Myr, particularly during periods of severe climatic changes. We estimate that the Przewalski's and domestic horse populations diverged 38-72 kyr BP, and find no evidence of recent admixture between the domestic horse breeds and the Przewalski's horse investigated. This supports the contention that Przewalski's horses represent the last surviving wild horse population(6). We find similar levels of genetic variation among Przewalski's and domestic populations, indicating that the former are genetically viable and worthy of conservation efforts. We also find evidence for continuous selection on the immune system and olfaction throughout horse evolution. Finally, we identify 29 genomic regions among horse breeds that deviate from neutrality and show low levels of genetic variation compared to the Przewalski's horse. Such regions could correspond to loci selected early during domestication.
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| 4. |
- Schöche, Stefan, et al.
(author)
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Infrared ellipsometry and near-infrared-to-vacuum-ultraviolet ellipsometry study of free-charge carrier properties in In-polar p-type InN
- 2012
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In: MRS Proceedings Volume 1396. - : Springer Science and Business Media LLC. ; , s. o07-27
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Conference paper (peer-reviewed)abstract
- We apply infrared spectroscopic ellipsometry (IRSE) in combination with near-infrared to vacuum-ultraviolet ellipsometry to study the concentration and mobility of holes in a set of Mg-doped In-polar InN samples of different Mg-concentrations. P-type behavior is found in the IRSE spectra for Mg-concentrations between 1x1018 cm-3 and 3x1019 cm-3. The free-charge carrier parameters are determined using a parameterized model that accounts for phonon-plasmon coupling. From the NIR-VUV data information about layer thicknesses, surface roughness, and structural InN layer properties are extracted and related to the IRSE results.
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| 5. |
- Zhou, Mi, et al.
(author)
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Direct graphene growth on Co3O4(111) by molecular beam epitaxy
- 2012
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In: Journal of Physics. - : Institute of Physics. - 0953-8984 .- 1361-648X. ; 24:7, s. 072201-
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Journal article (peer-reviewed)abstract
- Direct growth of graphene on Co3O4(111) at 1000 K was achieved by molecular beam epitaxy from a graphite source. Auger spectroscopy shows a characteristic sp(2) carbon lineshape, at average carbon coverages from 0.4 to 3 ML. Low energy electron diffraction (LEED) indicates (111) ordering of the sp2 carbon film with a lattice constant of 2.5(+/-0.1) angstrom characteristic of graphene. Sixfold symmetry of the graphene diffraction spots is observed at 0.4, 1 and 3 ML. The LEED data also indicate an average domain size of similar to 1800 angstrom, and show an incommensurate interface with the Co3O4(111) substrate, where the latter exhibits a lattice constant of 2.8(+/-0.1) angstrom. Core level photoemission shows a characteristically asymmetric C(1s) feature, with the expected pi to pi* satellite feature, but with a binding energy for the 3 ML film of 284.9(+/-0.1) eV, indicative of substantial graphene-to-oxide charge transfer. Spectroscopic ellipsometry data demonstrate broad similarity with graphene samples physically transferred to SiO2 or grown on SiC substrates, but with the pi to pi* absorption blue-shifted, consistent with charge transfer to the substrate. The ability to grow graphene directly on magnetically and electrically polarizable substrates opens new opportunities for industrial scale development of charge- and spin-based devices.
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