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Plasmon resonance of gold and silver nanoparticle arrays in the Kretschmann (attenuated total reflectance) vs. direct incidence configuration. Sci Rep 2022; 12:15738. [PMID: 36130995 PMCID: PMC9492765 DOI: 10.1038/s41598-022-20117-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
While the behaviour of plasmonic solid thin films in the Kretschmann (also known as Attenuated Total Reflection, ATR) configuration is well-understood, the use of discrete nanoparticle arrays in this optical configuration is not thoroughly explored. It is important to do so, since close packed plasmonic nanoparticle arrays exhibit exceptionally strong light-matter interactions by plasmonic coupling. The present work elucidates the optical properties of plasmonic Au and Ag nanoparticle arrays in both the direct normal incidence and Kretschmann configuration by numerical models, that are validated experimentally. First, hexagonal close packed Au and Ag nanoparticle films/arrays are obtained by air–liquid interfacial assembly. The numerical models for the rigorous solution of the Maxwell’s equations are validated using experimental optical spectra of these films before systematically investigating various parameters. The individual far-field/near-field optical properties, as well as the plasmon relaxation mechanism of the nanoparticles, vary strongly as the packing density of the array increases. In the Kretschmann configuration, the evanescent fields arising from p- and s-polarized (or TM and TE polarized) incidence have different directional components. The local evanescent field intensity and direction depends on the polarization, angle of incidence and the wavelength of incidence. These factors in the Kretschmann configuration give rise to interesting far-field as well as near-field optical properties. Overall, it is shown that plasmonic nanoparticle arrays in the Kretschmann configuration facilitate strong broadband absorptance without transmission losses, and strong near-field enhancement. The results reported herein elucidate the optical properties of self-assembled nanoparticle films, pinpointing the ideal conditions under which the normal and the Kretschmann configuration can be exploited in multiple light-driven applications.
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Seidenstücker A, Beirle S, Enderle F, Ziemann P, Marti O, Plettl A. Nanoporous silicon nitride-based membranes of controlled pore size, shape and areal density: Fabrication as well as electrophoretic and molecular filtering characterization. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1390-1398. [PMID: 29977673 PMCID: PMC6009373 DOI: 10.3762/bjnano.9.131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Accepted: 04/03/2018] [Indexed: 05/26/2023]
Abstract
A new route will be presented for an all-parallel fabrication of highly flexible, freestanding membranes with well-defined porosity. This fabrication is based on arrays of well-defined Au nanoparticles (NPs) exhibiting a high degree of hexagonal order as obtained in a first step by a proven micellar approach. These NP arrays serve as masks in a second reactive ion etching (RIE) step optimized for etching Si and some important Si compounds (silicon oxide, silicon nitride) on the nanoscale. Application to commercially available silicon nitride membranes of well-defined thickness, delivers a diaphragm with millions of nanopores of intended and controlled size, shape, and areal density with narrow distributions of these parameters. Electrophoretic transport measurements indicated a very low flow resistance of these porous membranes in ionic solutions as expected theoretically. Size-selective separation of protein molecules was demonstrated by real-time fluorescence microscopy.
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Affiliation(s)
- Axel Seidenstücker
- Institute of Solid State Physics, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Stefan Beirle
- Institute for Applied Materials, KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Fabian Enderle
- Institute of Solid State Physics, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Paul Ziemann
- Institute of Solid State Physics, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Othmar Marti
- Institute of Experimental Physics, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Alfred Plettl
- Institute of Solid State Physics, Ulm University, Albert-Einstein-Allee 11, 89069 Ulm, Germany
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Schilling M, Ziemann P, Zhang Z, Biskupek J, Kaiser U, Wiedwald U. Orientation of FePt nanoparticles on top of a-SiO2/Si(001), MgO(001) and sapphire(0001): effect of thermal treatments and influence of substrate and particle size. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2016; 7:591-604. [PMID: 27335749 PMCID: PMC4901541 DOI: 10.3762/bjnano.7.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 04/07/2016] [Indexed: 06/06/2023]
Abstract
Texture formation and epitaxy of thin metal films and oriented growth of nanoparticles (NPs) on single crystal supports are of general interest for improved physical and chemical properties especially of anisotropic materials. In the case of FePt, the main focus lies on its highly anisotropic magnetic behavior and its catalytic activity, both due to the chemically ordered face-centered tetragonal (fct) L10 phase. If the c-axis of the tetragonal system can be aligned normal to the substrate plane, perpendicular magnetic recording could be achieved. Here, we study the orientation of FePt NPs and films on a-SiO2/Si(001), i.e., Si(001) with an amorphous (a-) native oxide layer on top, on MgO(001), and on sapphire(0001) substrates. For the NPs of an approximately equiatomic composition, two different sizes were chosen: "small" NPs with diameters in the range of 2-3 nm and "large" ones in the range of 5-8 nm. The 3 nm thick FePt films, deposited by pulsed laser deposition (PLD), served as reference samples. The structural properties were probed in situ, particularly texture formation and epitaxy of the specimens by reflection high-energy electron diffraction (RHEED) and, in case of 3 nm nanoparticles, additionally by high-resolution transmission electron microscopy (HRTEM) after different annealing steps between 200 and 650 °C. The L10 phase is obtained at annealing temperatures above 550 °C for films and 600 °C for nanoparticles in accordance with previous reports. On the amorphous surface of a-SiO2/Si substrates we find no preferential orientation neither for FePt films nor nanoparticles even after annealing at 630 °C. On sapphire(0001) supports, however, FePt nanoparticles exhibit a clearly preferred (111) orientation even in the as-prepared state, which can be slightly improved by annealing at 600-650 °C. This improvement depends on the size of NPs: Only the smaller NPs approach a fully developed (111) orientation. On top of MgO(001) the effect of annealing on particle orientation was found to be strongest. From a random orientation in the as-prepared state observed for both, small and large FePt NPs, annealing at 650 °C for 30 min reorients the small particles towards a cube-on-cube epitaxial orientation with a minor fraction of (111)-oriented particles. In contrast, large FePt NPs keep their as-prepared random orientation even after doubling the annealing period at 650 °C to 60 min.
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Affiliation(s)
- Martin Schilling
- Institute of Solid State Physics, Ulm University, 89069 Ulm, Germany
- Institute of Surface Chemistry and Catalysis, Ulm University, 89069 Ulm, Germany
| | - Paul Ziemann
- Institute of Solid State Physics, Ulm University, 89069 Ulm, Germany
| | - Zaoli Zhang
- Electron Microscopy Group of Materials Science, Ulm University, 89069 Ulm, Germany
- Erich Schmid Institute of Materials Science, Jahnstrasse 12, 8700 Leoben, Austria
| | - Johannes Biskupek
- Electron Microscopy Group of Materials Science, Ulm University, 89069 Ulm, Germany
| | - Ute Kaiser
- Electron Microscopy Group of Materials Science, Ulm University, 89069 Ulm, Germany
| | - Ulf Wiedwald
- Institute of Solid State Physics, Ulm University, 89069 Ulm, Germany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany
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Zito G, Rusciano G, Pesce G, Malafronte A, Di Girolamo R, Ausanio G, Vecchione A, Sasso A. Nanoscale engineering of two-dimensional disordered hyperuniform block-copolymer assemblies. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:050601. [PMID: 26651630 DOI: 10.1103/physreve.92.050601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Indexed: 06/05/2023]
Abstract
Disordered hyperuniform (DH) media have been recognized as a new state of disordered matter that broadens our vision of material engineering. Here, long-range correlated disordered two-dimensional patterns are fabricated by self-assembling of spherical diblock-copolymer (BCP) micelles. Control of the self-assembling parameters leads to the formation of DH patterns of micelles that can host nanoscale material inclusions, therefore providing an effective strategy for fabricating multimaterial DH structures at molecular scale. Centroidal patterns are accurately determined by virtue of BCP micelles loaded with metal nanoparticles. Our analysis reveals the signature of nearly ideal DH BCP assemblies in the local density fluctuation and a dominant linear scaling in the local number fluctuation.
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Affiliation(s)
- Gianluigi Zito
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
| | - Giulia Rusciano
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
| | - Giuseppe Pesce
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
| | - Anna Malafronte
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
| | - Rocco Di Girolamo
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
| | - Giovanni Ausanio
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
- Consiglio Nazionale delle Ricerche-SPIN, via Cintia I-80126 Napoli, Italy
| | - Antonio Vecchione
- Università degli Studi di Salerno, via Giovanni Paolo II 132, 84084 Fisciano (Sa), Italy
- Consiglio Nazionale delle Ricerche-SPIN U.O.S Salerno, via Giovanni Paolo II 132, 84084 Fisciano (Sa), Italy
| | - Antonio Sasso
- Università degli Studi di Napoli Federico II, via Cintia I-80126 Napoli, Italy
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Morisada S, Kojima S, Sumi T, Kawakita H, Ohto K. Fabrication of non-close-packed colloidal monolayers by convective self-assembly using cationic polyelectrolyte-grafted silica particles. Colloid Polym Sci 2015. [DOI: 10.1007/s00396-015-3706-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Surface Attachment of Gold Nanoparticles Guided by Block Copolymer Micellar Films and Its Application in Silicon Etching. MATERIALS 2015; 8:3793-3805. [PMID: 28793407 PMCID: PMC5455671 DOI: 10.3390/ma8073793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 06/14/2015] [Accepted: 06/17/2015] [Indexed: 11/17/2022]
Abstract
Patterning metallic nanoparticles on substrate surfaces is important in a number of applications. However, it remains challenging to fabricate such patterned nanoparticles with easily controlled structural parameters, including particle sizes and densities, from simple methods. We report on a new route to directly pattern pre-formed gold nanoparticles with different diameters on block copolymer micellar monolayers coated on silicon substrates. Due to the synergetic effect of complexation and electrostatic interactions between the micellar cores and the gold particles, incubating the copolymer-coated silicon in a gold nanoparticles suspension leads to a monolayer of gold particles attached on the coated silicon. The intermediate micellar film was then removed using oxygen plasma treatment, allowing the direct contact of the gold particles with the Si substrate. We further demonstrate that the gold nanoparticles can serve as catalysts for the localized etching of the silicon substrate, resulting in nanoporous Si with a top layer of straight pores.
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Özdemir B, Huang W, Plettl A, Ziemann P. Arrays of quasi-hexagonally ordered silica nanopillars with independently controlled areal density, diameter and height gradients. NANOTECHNOLOGY 2015; 26:115301. [PMID: 25707314 DOI: 10.1088/0957-4484/26/11/115301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A consecutive fabrication approach of independently tailored gradients of the topographical parameters distance, diameter and height in arrays of well-ordered nanopillars on smooth SiO2-Si-wafers is presented. For this purpose, previously reported preparation techniques are further developed and combined. First, self-assembly of Au-salt loaded micelles by dip-coating with computer-controlled pulling-out velocities and subsequent hydrogen plasma treatment produce quasi-hexagonally ordered, 2-dimensional arrays of Au nanoparticles (NPs) with unidirectional variations of the interparticle distances along the pulling direction between 50-120 nm. Second, the distance (or areal density) gradient profile received in this way is superimposed with a diameter-controlled gradient profile of the NPs applying a selective photochemical growth technique. For demonstration, a 1D shutter is used for locally defined UV exposure times to prepare Au NP size gradients varying between 12 and 30 nm. Third, these double-gradient NP arrangements serve as etching masks in a following reactive ion etching step delivering arrays of nanopillars. For height gradient generation, the etching time is locally controlled by applying a shutter made from Si wafer piece. Due to the high flexibility of the etching process, the preparation route works on various materials such as cover slips, silicon, silicon oxide, silicon nitride and silicon carbide.
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Affiliation(s)
- Burcin Özdemir
- Institute of Solid State Physics, Ulm University, Albert-Einstein-Allee 11, D-89069 Ulm, Germany
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8
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Duvigneau J, Kutnyanszky E, Phang IY, Chung HJ, Wu H, Dos Ramos L, Gädt T, Yusoff SFM, Hempenius MA, Manners I, Vancso GJ. Raft crystals of poly(isoprene)-block-poly(ferrocenyldimethylsilane) and their surface wetting behavior during melting as observed by AFM and NanoTA. POLYMER 2014. [DOI: 10.1016/j.polymer.2014.04.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Terekhin VV, Zaitseva AV, Dement’eva OV, Rudoy VM. New two-dimensional polymer-metal composites based on highly ordered ensembles of nanoparticles. Design and optical properties. COLLOID JOURNAL 2013. [DOI: 10.1134/s1061933x13060161] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Fiedler J, Özdemir B, Bartholomä J, Plettl A, Brenner RE, Ziemann P. The effect of substrate surface nanotopography on the behavior of multipotnent mesenchymal stromal cells and osteoblasts. Biomaterials 2013; 34:8851-9. [DOI: 10.1016/j.biomaterials.2013.08.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 08/03/2013] [Indexed: 12/13/2022]
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Boyd DA, Hao Y, Li C, Goodwin DG, Haile SM. Block copolymer lithography of rhodium nanoparticles for high temperature electrocatalysis. ACS NANO 2013; 7:4919-4923. [PMID: 23713545 DOI: 10.1021/nn400156y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We present a method for forming ordered rhodium nanostructures on a solid support. The approach makes use of a block copolymer to create and assemble rhodium chloride nanoparticles from solution onto a surface; subsequent plasma and thermal processing are employed to remove the polymer and fully convert the nanostructures to metallic rhodium. Films cast from a solution of the triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) dissolved in toluene with rhodium(III) chloride hydrate were capable of producing a monolayer of rhodium nanoparticles of uniform size and interparticle spacing. The nanostructures were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The electrocatalytic performance of the nanoparticles was investigated with AC impedance spectroscopy. We observed that the addition of the particles to a model solid oxide fuel cell anode provided up to a 14-fold improvement in the anode activity as evidenced by a decrease in the AC impedance resistance. Examination of the anode after electrochemical measurement revealed that the basic morphology and distribution of the particles were preserved.
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Affiliation(s)
- David A Boyd
- Division of Physics, Mathematics & Astronomy, California Institute of Technology, Pasadena, California 91125, USA.
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Ramanathan M, Darling SB. Nanofabrication with metallopolymers - recent developments and future perspectives. POLYM INT 2013. [DOI: 10.1002/pi.4541] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Muruganathan Ramanathan
- Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Laboratory; Oak Ridge TN 37831 USA
| | - Seth B. Darling
- Center for Nanoscale Materials; Argonne National Laboratory; Argonne IL 60439 USA
- Institute for Molecular Engineering; University of Chicago; Chicago IL 60637 USA
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13
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Özdemir B, Seidenstücker A, Plettl A, Ziemann P. Cyclic photochemical re-growth of gold nanoparticles: Overcoming the mask-erosion limit during reactive ion etching on the nanoscale. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2013; 4:886-94. [PMID: 24367758 PMCID: PMC3869346 DOI: 10.3762/bjnano.4.100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/29/2013] [Indexed: 05/05/2023]
Abstract
THE BASIC IDEA OF USING HEXAGONALLY ORDERED ARRAYS OF AU NANOPARTICLES (NP) ON TOP OF A GIVEN SUBSTRATE AS A MASK FOR THE SUBSEQUENT ANISOTROPIC ETCHING IN ORDER TO FABRICATE CORRESPONDINGLY ORDERED ARRAYS OF NANOPILLARS MEETS TWO SERIOUS OBSTACLES: The position of the NP may change during the etching process and, thus, the primary pattern of the mask deteriorates or is completely lost. Furthermore, the NP are significantly eroded during etching and, consequently, the achievable pillar height is strongly restricted. The present work presents approaches on how to get around both problems. For this purpose, arrays of Au NPs (starting diameter 12 nm) are deposited on top of silica substrates by applying diblock copolymer micelle nanolithography (BCML). It is demonstrated that evaporated octadecyltrimethoxysilane (OTMS) layers act as stabilizer on the NP position, which allows for an increase of their size up to 50 nm by an electroless photochemical process. In this way, ordered arrays of silica nanopillars are obtained with maximum heights of 270 nm and aspect ratios of 5:1. Alternatively, the NP position can be fixed by a short etching step with negligible mask erosion followed by cycles of growing and reactive ion etching (RIE). In that case, each cycle is started by photochemically re-growing the Au NP mask and thereby completely compensating for the erosion due to the previous cycle. As a result of this mask repair method, arrays of silica nanopillar with heights up to 680 nm and aspect ratios of 10:1 are fabricated. Based on the given recipes, the approach can be applied to a variety of materials like silicon, silicon oxide, and silicon nitride.
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Affiliation(s)
- Burcin Özdemir
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
| | | | - Alfred Plettl
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
| | - Paul Ziemann
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
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Ye Z, Tangeysh B, Wayland BB. Metal dication cross-linked polymer network colloids as an approach to form and stabilize unusually small metal nanoparticles. Chem Commun (Camb) 2013; 49:5372-4. [DOI: 10.1039/c3cc41778f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Enderle F, Dubbers O, Plettl A, Ziemann P. Controlled positioning of nanoparticles on a micrometer scale. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2012; 3:773-7. [PMID: 23213640 PMCID: PMC3512126 DOI: 10.3762/bjnano.3.86] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 10/18/2012] [Indexed: 05/07/2023]
Abstract
For many applications it is desirable to have nanoparticles positioned on top of a given substrate well separated from each other and arranged in arrays of a certain geometry. For this purpose, a method is introduced combining the bottom-up self-organization of precursor-loaded micelles providing Au nanoparticles (NPs), with top-down electron-beam lithography. As an example, 13 nm Au NPs are arranged in a square array with interparticle distances >1 µm on top of Si substrates. By using these NPs as masks for a subsequent reactive ion etching, the square pattern is transferred into Si as a corresponding array of nanopillars.
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Affiliation(s)
- Fabian Enderle
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
| | - Oliver Dubbers
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
| | - Alfred Plettl
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
| | - Paul Ziemann
- Institute of Solid State Physics, Ulm University, D-89069 Ulm, Germany
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Han L, Wiedwald U, Biskupek J, Fauth K, Kaiser U, Ziemann P. Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2011; 2:473-485. [PMID: 22003453 PMCID: PMC3190617 DOI: 10.3762/bjnano.2.51] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 07/31/2011] [Indexed: 05/31/2023]
Abstract
The thermally activated formation of nanoscale CoPt alloys was investigated, after deposition of self-assembled Co nanoparticles on textured Pt(111) and epitaxial Pt(100) films on MgO(100) and SrTiO(3)(100) substrates, respectively. For this purpose, metallic Co nanoparticles (diameter 7 nm) were prepared with a spacing of 100 nm by deposition of precursor-loaded reverse micelles, subsequent plasma etching and reduction on flat Pt surfaces. The samples were then annealed at successively higher temperatures under a H(2) atmosphere, and the resulting variations of their structure, morphology and magnetic properties were characterized. We observed pronounced differences in the diffusion and alloying of Co nanoparticles on Pt films with different orientations and microstructures. On textured Pt(111) films exhibiting grain sizes (20-30 nm) smaller than the particle spacing (100 nm), the formation of local nanoalloys at the surface is strongly suppressed and Co incorporation into the film via grain boundaries is favoured. In contrast, due to the absence of grain boundaries on high quality epitaxial Pt(100) films with micron-sized grains, local alloying at the film surface was established. Signatures of alloy formation were evident from magnetic investigations. Upon annealing to temperatures up to 380 °C, we found an increase both of the coercive field and of the Co orbital magnetic moment, indicating the formation of a CoPt phase with strongly increased magnetic anisotropy compared to pure Co. At higher temperatures, however, the Co atoms diffuse into a nearby surface region where Pt-rich compounds are formed, as shown by element-specific microscopy.
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Affiliation(s)
- Luyang Han
- Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Ulf Wiedwald
- Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Johannes Biskupek
- Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Kai Fauth
- Experimentelle Physik IV, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ute Kaiser
- Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Paul Ziemann
- Institut für Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
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Muralidharan G, Sivaraman SK, Santhanam V. Effect of substrate on particle arrangement in arrays formed by self-assembly of polymer grafted nanoparticles. NANOSCALE 2011; 3:2138-2141. [PMID: 21445398 DOI: 10.1039/c1nr10086f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We show that the substrate affects the interparticle spacing in monolayer arrays with hexagonal order formed by self-assembly of polymer grafted nanoparticles. Remarkably, arrays with square packing were formed due to convective shearing at a liquid surface induced by miscibility of colloidal solution with the substrate.
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Affiliation(s)
- Girish Muralidharan
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, 560012, India
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18
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Nanopatterning by block copolymer micelle nanolithography and bioinspired applications. Biointerphases 2011; 6:MR1-12. [DOI: 10.1116/1.3536839] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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19
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Eyrich M, Kielbassa S, Diemant T, Biskupek J, Kaiser U, Wiedwald U, Ziemann P, Bansmann J. Planar Au/TiO2 Model Catalysts: Fabrication, Characterization and Catalytic Activity. Chemphyschem 2010; 11:1430-7. [DOI: 10.1002/cphc.200900942] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Härtling T, Seidenstücker A, Olk P, Plettl A, Ziemann P, Eng LM. Controlled photochemical particle growth in two-dimensional ordered metal nanoparticle arrays. NANOTECHNOLOGY 2010; 21:145309. [PMID: 20234077 DOI: 10.1088/0957-4484/21/14/145309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We report on a universal technique which allows us to precisely manipulate the diameter of metal nanoparticles in two-dimensional particle arrays. The approach is demonstrated here for hexagonally ordered gold nanoparticle arrays fabricated by means of diblock copolymer micelle lithography (BCML). The particles are used as nucleation centers in seed-mediated photochemical metal deposition, whereby the particle diameter increases. Repeatedly combining photochemical growth with thermal annealing steps additionally facilitates controlling the shape of the particles.
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Affiliation(s)
- Thomas Härtling
- Institut für Angewandte Photophysik, Technische Universität Dresden, Dresden, Germany.
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Rajesh K, Sreedhar B, Radhakrishnan TP. Assembly of Gold Nanoparticles on a Molecular Ultrathin Film: Tuning the Surface Plasmon Resonance. Chemphyschem 2010; 11:1780-6. [DOI: 10.1002/cphc.200900675] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Fleischer M, Zhang D, Braun K, Jäger S, Ehlich R, Häffner M, Stanciu C, Hörber JKH, Meixner AJ, Kern DP. Tailoring gold nanostructures for near-field optical applications. NANOTECHNOLOGY 2010; 21:065301. [PMID: 20057031 DOI: 10.1088/0957-4484/21/6/065301] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A method of combined thin-film deposition, electron beam lithography, and ion milling is presented for the fabrication of gold and silver nanostructures. The flexibility of lithographical processes for the variation of geometric parameters is combined with three-dimensional control over the surface evolution. Depending on the etching angle, different shapes ranging from cones over rods to cups can be achieved. These size- and shape-tunable structures present a toolbox for nano-optical investigations. As an example, optical properties of systematically varying structures are examined in a parabolic mirror confocal microscope.
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Affiliation(s)
- M Fleischer
- Institute of Applied Physics, Eberhard Karls Universität Tübingen, Tübingen, Germany.
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23
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Wiedwald U, Han L, Biskupek J, Kaiser U, Ziemann P. Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2010; 1:24-47. [PMID: 21977392 PMCID: PMC3045932 DOI: 10.3762/bjnano.1.5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 11/06/2010] [Indexed: 05/07/2023]
Abstract
Monatomic (Fe, Co) and bimetallic (FePt and CoPt) nanoparticles were prepared by exploiting the self-organization of precursor loaded reverse micelles. Achievements and limitations of the preparation approach are critically discussed. We show that self-assembled metallic nanoparticles can be prepared with diameters d = 2-12 nm and interparticle distances D = 20-140 nm on various substrates. Structural, electronic and magnetic properties of the particle arrays were characterized by several techniques to give a comprehensive view of the high quality of the method. For Co nanoparticles, it is demonstrated that magnetostatic interactions can be neglected for distances which are at least 6 times larger than the particle diameter. Focus is placed on FePt alloy nanoparticles which show a huge magnetic anisotropy in the L1(0) phase, however, this is still less by a factor of 3-4 when compared to the anisotropy of the bulk counterpart. A similar observation was also found for CoPt nanoparticles (NPs). These results are related to imperfect crystal structures as revealed by HRTEM as well as to compositional distributions of the prepared particles. Interestingly, the results demonstrate that the averaged effective magnetic anisotropy of FePt nanoparticles does not strongly depend on size. Consequently, magnetization stability should scale linearly with the volume of the NPs and give rise to a critical value for stability at ambient temperature. Indeed, for diameters above 6 nm such stability is observed for the current FePt and CoPt NPs. Finally, the long-term conservation of nanoparticles by Au photoseeding is presented.
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Affiliation(s)
- Ulf Wiedwald
- Institut für Festkörperphysik, Universität Ulm, 89069 Ulm, Germany
| | - Luyang Han
- Institut für Festkörperphysik, Universität Ulm, 89069 Ulm, Germany
| | - Johannes Biskupek
- Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, 89069 Ulm, Germany
| | - Ute Kaiser
- Materialwissenschaftliche Elektronenmikroskopie, Universität Ulm, 89069 Ulm, Germany
| | - Paul Ziemann
- Institut für Festkörperphysik, Universität Ulm, 89069 Ulm, Germany
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Rahme K, Vicendo P, Ayela C, Gaillard C, Payré B, Mingotaud C, Gauffre F. A Simple Protocol to Stabilize Gold Nanoparticles using Amphiphilic Block Copolymers: Stability Studies and Viable Cellular Uptake. Chemistry 2009; 15:11151-9. [DOI: 10.1002/chem.200901564] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Kannaiyan D, Cha MA, Jang YH, Sohn BH, Huh J, Park C, Kim DH. Efficient photocatalytic hybrid Ag/TiO2 nanodot arrays integrated into nanopatterned block copolymer thin films. NEW J CHEM 2009. [DOI: 10.1039/b9nj00245f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Qu S, Zhang XW, Gao Y, You JB, Fan YM, Yin ZG, Chen NF. Composition deviation of arrays of FePt nanoparticles starting from poly(styrene)-poly(4-vinylpyridine) micelles. NANOTECHNOLOGY 2008; 19:135704. [PMID: 19636158 DOI: 10.1088/0957-4484/19/13/135704] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ordered arrays of FePt nanoparticles were prepared using a diblock polymer micellar method combined with plasma treatment. Rutherford backscattering spectroscopy analyses reveal that the molar ratios of Fe to Pt in metal-salt-loaded micelles deviate from those when metal precursors are added, and that the plasma treatment processes have little influence upon the compositions of the resulting FePt nanoparticles. The results from Fourier transform infrared spectroscopy show that the maximum loadings of FeCl(3) and H(2)PtCl(6) inside poly(styrene)-poly(4-vinylpyridine) micelles are different. The composition deviation of FePt nanoparticles is attributed to the fact that one FeCl(3) molecule coordinates with a single 4-vinylpyridine (4VP) unit, while two neighboring and uncomplexed 4VP units are required for one H(2)PtCl(6) molecule. Additionally, we demonstrate that the center-to-center distances of the neighboring FePt nanoparticles can also be tuned by varying the drawing velocity.
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Affiliation(s)
- S Qu
- Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, People's Republic of China
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