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Oates, Thomas W.H.
Alternative names
Publications (4 of 4) Show all publications
Abrasonis, G., Oates, T., Kovacs, G. J., Grenzer, J., Persson, P., Heinig, K.-H. H., . . . Moeller, W. (2010). Nanoscale precipitation patterns in carbon-nickel nanocomposite thin films: Period and tilt control via ion energy and deposition angle. JOURNAL OF APPLIED PHYSICS, 108(4), 043503
Open this publication in new window or tab >>Nanoscale precipitation patterns in carbon-nickel nanocomposite thin films: Period and tilt control via ion energy and deposition angle
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2010 (English)In: JOURNAL OF APPLIED PHYSICS, ISSN 0021-8979, Vol. 108, no 4, p. 043503-Article in journal (Refereed) Published
Abstract [en]

Periodic precipitation patterns in C:Ni nanocomposites grown by energetic ion codeposition are investigated. Films were grown at room temperature by ionized physical vapor deposition using a pulsed filtered cathodic vacuum arc. We reveal the role of the film composition, ion energy and incidence angle on the film morphology using transmission electron microscopy and grazing incidence small angle x-ray scattering. Under these growth conditions, phase separation occurs in a thin surface layer which has a high atomic mobility due to energetic ion impacts. This layer is an advancing reaction front, which switches to an oscillatory mode, producing periodic precipitation patterns. Our results show that the ion induced atomic mobility is not random, as it would be in the case of thermal diffusion but conserves to a large extent the initial direction of the incoming ions. This results in a tilted pattern under oblique ion incidence. A dependence of the nanopattern periodicity and tilt on the growth parameters is established and pattern morphology control via ion velocity is demonstrated.

Place, publisher, year, edition, pages
American Institute of Physics, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-60235 (URN)10.1063/1.3467521 (DOI)000281857100034 ()
Note
Original Publication: Gintautas Abrasonis, Thomas Oates, Gyoergy J Kovacs, Joerg Grenzer, Per Persson, Karl-Heinz H Heinig, Andrius Martinavicius, Nicole Jeutter, Carsten Baehtz, Mark Tucker, Marcela M M Bilek and Wolfhard Moeller, Nanoscale precipitation patterns in carbon-nickel nanocomposite thin films: Period and tilt control via ion energy and deposition angle, 2010, JOURNAL OF APPLIED PHYSICS, (108), 4, 043503. http://dx.doi.org/10.1063/1.3467521 Copyright: American Institute of Physics http://www.aip.org/ Available from: 2010-10-08 Created: 2010-10-08 Last updated: 2015-03-09
Ranjan, M., Oates, T., Facsko, S. & Moeller, W. (2010). Optical properties of silver nanowire arrays with 35 nm periodicity. OPTICS LETTERS, 35(15), 2576-2578
Open this publication in new window or tab >>Optical properties of silver nanowire arrays with 35 nm periodicity
2010 (English)In: OPTICS LETTERS, ISSN 0146-9592, Vol. 35, no 15, p. 2576-2578Article in journal (Refereed) Published
Abstract [en]

We present highly ordered Ag nanowire arrays with 35 nm periodicity grown on patterned templates. The optical properties measured using generalized ellipsometry exhibit strong anisotropy. Dielectric functions are calculated by fitting the Jones matrix elements with a biaxial layer model, accounting for both metallic behavior and localized surface plasmon resonances. The amplitude and wavelength maximum of the plasmon resonance perpendicular to the wires increase with increasing wire width and thickness. The dielectric coefficients of 10-mm-wide nanowires show a transition behavior from insulating in UV to metallic above 550 nm. Their potential application as polarization-dependent plasmonic-scattering transparent conductive electrodes is discussed.

Place, publisher, year, edition, pages
Optical Society of America, 2010
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58952 (URN)10.1364/OL.35.002576 (DOI)000281056700026 ()20680063 (PubMedID)
Available from: 2010-09-03 Created: 2010-09-03 Last updated: 2010-09-06
Oates, T. W. .., Sugime, H. & Noda , S. (2009). Combinatorial surface-enhanced raman spectroscopy and spectroscopic ellipsometry of silver Island films. Journal of Physical Chemistry C, 113(12), 4820-4828
Open this publication in new window or tab >>Combinatorial surface-enhanced raman spectroscopy and spectroscopic ellipsometry of silver Island films
2009 (English)In: Journal of Physical Chemistry C, ISSN 1932-7447, Vol. 113, no 12, p. 4820-4828Article in journal (Refereed) Published
Abstract [en]

Utilizing a combinatorial method, we used spectroscopic ellipsometry to determine the dielectric functions of silver island films over a large range of sizes and morphologies from the percolation threshold down to average particle size smaller than 5 nm. We measured films on silicon substrates with 2 and 20 nm oxide layers and compared the surface-enhanced Raman scattering properties of the films. As expected, the films on 20-nm-thick oxide substrates showed increased Raman counts due to reduced damping of the plasmon resonance; however, the optical absorption was greater in the films on 2 nm oxide. The maximum Raman scattering was observed for average particle diameters of 13.6 and 25 nm and interparticle spacings of 3.3 and 4.1 nm for the 2 and 20 nm oxide substrates, respectively. The use of a combinatorial method resulted in significantly reduced uncertainties by avoiding multiple sample preparations and allowed unambiguous identification of optimal film parameters for the different substrates.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-18789 (URN)10.1021/jp8097654 (DOI)
Available from: 2009-06-05 Created: 2009-06-03 Last updated: 2009-06-05
Oates, T., Shiratori, Y. & Noda, S. (2009). Two-dimensional combinatorial investigation of raman and fluorescence enhancement in silver and gold sandwich substrates. Journal of Physical Chemistry C, 113(22), 9588-9594
Open this publication in new window or tab >>Two-dimensional combinatorial investigation of raman and fluorescence enhancement in silver and gold sandwich substrates
2009 (English)In: Journal of Physical Chemistry C, ISSN 1932-7447, Vol. 113, no 22, p. 9588-9594Article in journal (Refereed) Published
Abstract [en]

We present a two-dimensional combinatorial investigation of resonant Raman and fluorescence enhancement in silver and gold sandwich structures. Gold and silver, separated by a thin alumina spacer layer, were deposited in two orthogonal gradients, with a thickness from a few hundred to a few nanometers, covering the range from island films through percolation to continuous films. Resonant Raman spectra of Rhodamine 6G adsorbed on the substrate surface were recorded in a 13 × 13 matrix using an automated scanning stage. The most Raman-active substrates were composed of silver (8 nm)-on-alumina (7 nm)-on-gold (5 nm). They consist of both gold and silver discontinuous nanoparticle films separated by alumina, forming a labyrinthine network structure. Gold-on-alumina-on-silver substrates also displayed increased activity compared with that of goldon-alumina substrates. Maximum fluorescence intensity was observed on silver films nominally 35 nm thick covered by 8 nm of alumina. The efficacy of the combinatorial method to correlate multiple aspects of the measurements and reduce uncertainties is demonstrated.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-21327 (URN)10.1021/jp900436a (DOI)
Available from: 2009-09-30 Created: 2009-09-30 Last updated: 2009-09-30
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