Dépouillements

Viewing spin structures with soft X-ray microscopy / Peter Fischer in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 14-22 Titre : Viewing spin structures with soft X-ray microscopy Type de document : texte imprimé Auteurs : Peter Fischer, Auteur Année de publication : 2011 Article en page(s) : pp. 14-22 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : X-ray  Microscopy  Magnetic  microscopies  Electron  X-ray  optics Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : The spin of the electron and it's associated magnetic moment marks the basic unit for magnetic properties of matter [1] and [2] . Magnetism, in particular ferromagnetism and antiferromagnetism is described by a collective order of these spins, where the interaction between individual spins reflects a competition between exchange, anisotropy and dipolar energy terms. As a result the energetically favored ground state of a ferromagnetic system is a rather complex spin configuration, the magnetic domain structure3. Magnetism is one of the eldest scientific phenomena, yet it is one of the most powerful and versatile utilized physical effects in modern technologies, such as in magnetic storage and sensor devices. To achieve highest storage density, the relevant length scales, such as the bit size in disk drives is now approaching the nanoscale and as such further developments have to deal with nanoscience phenomena [4] , [5] , [6] , [7] , [8] and [9] . Advanced characterization tools are required to fully understand the underlying physical principles. Magnetic microscopes using polarized soft X-rays offer a close-up view into magnetism with unique features, these include elemental sensitivity due to X-ray magnetic dichroism effects as contrast mechanism, high spatial resolution provided by state-of-the-art X-ray optics and fast time resolution limited by the inherent time structure of current X-ray sources, which will be overcome with the introduction of ultrafast and high brilliant X-ray sources. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701619 [article] Viewing spin structures with soft X-ray microscopy [texte imprimé] / Peter Fischer, Auteur . - 2011 . - pp. 14-22. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 14-22 Mots-clés : X-ray  Microscopy  Magnetic  microscopies  Electron  X-ray  optics Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : The spin of the electron and it's associated magnetic moment marks the basic unit for magnetic properties of matter [1] and [2] . Magnetism, in particular ferromagnetism and antiferromagnetism is described by a collective order of these spins, where the interaction between individual spins reflects a competition between exchange, anisotropy and dipolar energy terms. As a result the energetically favored ground state of a ferromagnetic system is a rather complex spin configuration, the magnetic domain structure3. Magnetism is one of the eldest scientific phenomena, yet it is one of the most powerful and versatile utilized physical effects in modern technologies, such as in magnetic storage and sensor devices. To achieve highest storage density, the relevant length scales, such as the bit size in disk drives is now approaching the nanoscale and as such further developments have to deal with nanoscience phenomena [4] , [5] , [6] , [7] , [8] and [9] . Advanced characterization tools are required to fully understand the underlying physical principles. Magnetic microscopes using polarized soft X-rays offer a close-up view into magnetism with unique features, these include elemental sensitivity due to X-ray magnetic dichroism effects as contrast mechanism, high spatial resolution provided by state-of-the-art X-ray optics and fast time resolution limited by the inherent time structure of current X-ray sources, which will be overcome with the introduction of ultrafast and high brilliant X-ray sources. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701619

Bistability, higher harmonics, and chaos in AFM / Robert W. Stark in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 24-32 Titre : Bistability, higher harmonics, and chaos in AFM Type de document : texte imprimé Auteurs : Robert W. Stark, Auteur Année de publication : 2011 Article en page(s) : pp. 24-32 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : Bistability  Nanometres  Sensor  Force  electrostatic  Force  magnetic  Non-linearity  Nanoscale  material  Atomic  force Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : A dynamic atomic force microscope sensitively probes surface properties with subnanometre lateral resolution. In the amplitude modulation mode, the force-sensing tip oscillates a few nanometres. The force sensor is a harmonic oscillator that interacts with a barrier, which can be described as a non-linear potential consisting of an attractive well and a repulsive wall. Further non-linearities may be introduced by adhesion, electrostatic or magnetic forces. Thus, the character of the non-linearity is intimately related to the material properties. This review highlights the non-linear dynamics in the amplitude modulation mode and how they enable and affect nanoscale material characterisation. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701620 [article] Bistability, higher harmonics, and chaos in AFM [texte imprimé] / Robert W. Stark, Auteur . - 2011 . - pp. 24-32. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 24-32 Mots-clés : Bistability  Nanometres  Sensor  Force  electrostatic  Force  magnetic  Non-linearity  Nanoscale  material  Atomic  force Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : A dynamic atomic force microscope sensitively probes surface properties with subnanometre lateral resolution. In the amplitude modulation mode, the force-sensing tip oscillates a few nanometres. The force sensor is a harmonic oscillator that interacts with a barrier, which can be described as a non-linear potential consisting of an attractive well and a repulsive wall. Further non-linearities may be introduced by adhesion, electrostatic or magnetic forces. Thus, the character of the non-linearity is intimately related to the material properties. This review highlights the non-linear dynamics in the amplitude modulation mode and how they enable and affect nanoscale material characterisation. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701620

Charge-transfer with graphene and nanotubes / C.N.R. Rao in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 34–40 Titre : Charge-transfer with graphene and nanotubes Type de document : texte imprimé Auteurs : C.N.R. Rao, Auteur ; Rakesh Voggu, Auteur Année de publication : 2011 Article en page(s) : pp. 34–40 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : Charge-transfer  Electron  Acceptor  molecules  Graphene  Nanotubes Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Charge-transfer between electron–donor and –acceptor molecules is a widely studied subject of great chemical interest. Some of the charge-transfer compounds in solid state exhibit novel electronic properties. In the last two to three years, occurrence of molecular charge-transfer involving single-walled carbon nanotubes (SWNTs) and graphene has been demonstrated. This interaction gives rise to significant changes in the electronic properties of these nanocarbons. We examine charge-transfer phenomenon in graphene and SWNTs in this article in view of its potential utility in device applications. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701632 [article] Charge-transfer with graphene and nanotubes [texte imprimé] / C.N.R. Rao, Auteur ; Rakesh Voggu, Auteur . - 2011 . - pp. 34–40. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 34–40 Mots-clés : Charge-transfer  Electron  Acceptor  molecules  Graphene  Nanotubes Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Charge-transfer between electron–donor and –acceptor molecules is a widely studied subject of great chemical interest. Some of the charge-transfer compounds in solid state exhibit novel electronic properties. In the last two to three years, occurrence of molecular charge-transfer involving single-walled carbon nanotubes (SWNTs) and graphene has been demonstrated. This interaction gives rise to significant changes in the electronic properties of these nanocarbons. We examine charge-transfer phenomenon in graphene and SWNTs in this article in view of its potential utility in device applications. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701632

Why does paper get stronger as it dries? / Alvaro Tejado in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 42–49 Titre : Why does paper get stronger as it dries? Type de document : texte imprimé Auteurs : Alvaro Tejado, Auteur ; Theo G.M. Van de Ven, Auteur Année de publication : 2011 Article en page(s) : pp. 42–49 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : Paper  Wet  paper  Fiber  Friction  Capillary  forces Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Surprisingly the strength of wet paper is still poorly understood. Here we show that the traditional explanation of the strength of wet paper is incorrect. Observations that the capillary force in fiber crossings in wet paper approaches zero as the water is evaporated show that they are not responsible for the strength of wet paper. Instead we present evidence that fiber entanglements and friction are the cause. Like paper, films made of nanotubes, nanorods, nanofibers or nanoribbons also consist of randomly oriented fibers, and this field may well benefit from an increased knowledge of paper properties. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701644 [article] Why does paper get stronger as it dries? [texte imprimé] / Alvaro Tejado, Auteur ; Theo G.M. Van de Ven, Auteur . - 2011 . - pp. 42–49. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 42–49 Mots-clés : Paper  Wet  paper  Fiber  Friction  Capillary  forces Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Surprisingly the strength of wet paper is still poorly understood. Here we show that the traditional explanation of the strength of wet paper is incorrect. Observations that the capillary force in fiber crossings in wet paper approaches zero as the water is evaporated show that they are not responsible for the strength of wet paper. Instead we present evidence that fiber entanglements and friction are the cause. Like paper, films made of nanotubes, nanorods, nanofibers or nanoribbons also consist of randomly oriented fibers, and this field may well benefit from an increased knowledge of paper properties. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701644

New SPM techniques for analyzing OPV materials / Rajiv Giridharagopal in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 50–56 Titre : New SPM techniques for analyzing OPV materials Type de document : texte imprimé Auteurs : Rajiv Giridharagopal, Auteur ; Guozheng Shao, Auteur ; Chris Groves, Auteur Année de publication : 2011 Article en page(s) : pp. 50–56 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : OPV  materials  Solar  energy  Microscopy  Nanoscale  basis  Heterogeneity  of  OPV Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Organic solar cells hold promise as an economical means of harvesting solar energy due to their ease of production and processing. However, the efficiency of such organic photovoltaic (OPV) devices is currently below that required for widespread adoption. The efficiency of an OPV is inextricably linked to its nanoscale morphology. High-resolution metrology can play a key role in the discovery and optimization of new organic semiconductors in the lab, as well as assist the transition of OPVs from the lab to mass production. We review the instrumental issues associated with the application of scanning probe microscopy (SPM) techniques such as photoconductive atomic force microscopy and time-resolved electrostatic force microscopy that have been shown to be useful in the study of nanostructured organic solar cells. These techniques offer unique insight into the underlying heterogeneity of OPV devices and provide a nanoscale basis for understanding how morphology directly affects OPV operation. Finally, we discuss opportunities for further improvements in scanning probe microscopy to contribute to OPV development. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701656 [article] New SPM techniques for analyzing OPV materials [texte imprimé] / Rajiv Giridharagopal, Auteur ; Guozheng Shao, Auteur ; Chris Groves, Auteur . - 2011 . - pp. 50–56. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 50–56 Mots-clés : OPV  materials  Solar  energy  Microscopy  Nanoscale  basis  Heterogeneity  of  OPV Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Organic solar cells hold promise as an economical means of harvesting solar energy due to their ease of production and processing. However, the efficiency of such organic photovoltaic (OPV) devices is currently below that required for widespread adoption. The efficiency of an OPV is inextricably linked to its nanoscale morphology. High-resolution metrology can play a key role in the discovery and optimization of new organic semiconductors in the lab, as well as assist the transition of OPVs from the lab to mass production. We review the instrumental issues associated with the application of scanning probe microscopy (SPM) techniques such as photoconductive atomic force microscopy and time-resolved electrostatic force microscopy that have been shown to be useful in the study of nanostructured organic solar cells. These techniques offer unique insight into the underlying heterogeneity of OPV devices and provide a nanoscale basis for understanding how morphology directly affects OPV operation. Finally, we discuss opportunities for further improvements in scanning probe microscopy to contribute to OPV development. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701656

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