1,352 research outputs found
Evidence of Deep Water Penetration in Silica during Stress Corrosion Fracture
We measure the thickness of the heavy water layer trapped under the stress corrosion fracture surface of silica using neutron reflectivity experiments. We show that the penetration depth is 65–85 Å, suggesting the presence of a damaged zone of ~100 Å extending ahead of the crack tip during its propagation. This estimate of the size of the damaged zone is compatible with other recent results
Significant techniques in the processing and interpretation of ERTS-1 data
The discipline oriented investigations underway at the Johnson Space Center (JSC) using ERTS-1 data provide an appropriate framework for the systematic evaluation of the various elements comprising a prototype multispectral data processing and analysis system. In particular such a system may be thought of as the integration of: (1) a preprocessing subsystem; (2) a spectral clustering subsystem, (3) a correlation and classification subsystem; (4) mensuration subsystem; and (5) an information management subsystem. Specific elements of this system are already operational at JSC. It is in the context of this system that technique development and application is being pursued at JSC. Aircraft, ERTS and EREP data will be utilized to refine the subsystem elements for each of the data acquisition systems or system combinations that are optimally suited for a specific Earth Resources application. The techniques reported are those that have been developed to date during the utilization of ERTS-1 data in this processing and analysis system
Submicrometric Films of Surface-Attached Polymer Network with Temperature-Responsive Properties
Temperature-responsive properties of surface-attached
poly(N-isopropylacrylamide) (PNIPAM) network films with well-controlled
chemistry are investigated. The synthesis consists of cross-linking and
grafting preformed ene-reactive polymer chains through thiol--ene click
chemistry. The formation of surface-attached and cross-linked polymer films has
the advantage of being wellcontrolled without any caution of no-oxygen
atmosphere or addition of initiators. PNIPAM hydrogel films with same
cross-link density are synthesized on a wide range of thickness, from
nanometers to micrometers. The swelling-collapse transition with temperature is
studied by using ellipsometry, neutron reflectivity, and atomic force
microscopy as complementary surface-probing techniques. Sharp and high
amplitude temperature-induced phase transition is observed for all
submicrometric PNIPAM hydrogel films. For temperature above LCST,
surface-attached PNIPAM hydrogels collapse similarly but without complete
expulsion of water. For temperature below LCST, the swelling of PNIPAM
hydrogels depends on the film thickness. It is shown that the swelling is
strongly affected by the surface attachment for ultrathin films below 150
nm. For thicker films above 150 nm (to micrometers), surface-attached polymer
networks with the same cross-link density swell equally. The density profile of
the hydrogel films in the direction normal to the substrate is confronted with
in-plane topography of the free surface. It results that the free interface
width is much larger than the roughness of the hydrogel film, suggesting
pendant chains at the free surface.Comment: in Langmuir, American Chemical Society, 2015, LANGMUIR, 31 (42),
pp.11516-1152
Mass Density of Individual Cobalt Nanowires
The mass density of nanowires is determined using in-situ resonance frequency
experiments combined with quasi-static nanotensile tests. Our results reveal a
mass density of 7.36 g/cm3 on average which is below the theoretical density of
bulk cobalt. Also the density of electrodeposited cobalt nanowires is found to
decrease with the aspect ratio. The results are discussed in terms of the
measurement accuracy and the microstructure of the nanowires.Comment: 3 Figure
Universal scattering behavior of co-assembled nanoparticle-polymer clusters
Water-soluble clusters made from 7 nm inorganic nanoparticles have been
investigated by small-angle neutron scattering. The internal structure factor
of the clusters was derived and exhibited a universal behavior as evidenced by
a correlation hole at intermediate wave-vectors. Reverse Monte-Carlo
calculations were performed to adjust the data and provided an accurate
description of the clusters in terms of interparticle distance and volume
fraction. Additional parameters influencing the microstructure were also
investigated, including the nature and thickness of the nanoparticle adlayer.Comment: 5 pages, 4 figures, paper published in Physical Review
The role of electron polarization on nuclear spin diffusion
Dynamic nuclear polarization (DNP) is capable of boosting signals in nuclear
magnetic resonance by orders of magnitude by creating out-of-equilibrium
nuclear spin polarization. The diffusion of nuclear spin polarization in the
vicinity of paramagnetic dopants is a crucial step for DNP and remains yet not
well understood. In this Letter, we show that the polarization of the electron
spin controls the rate of proton spin diffusion in a DNP sample at 1.2 K and 7
T; at increasingly high electron polarization, spin diffusion vanishes. We
rationalize our results using a 2 nucleus - 1 electron model and Lindblad s
Master equation, which generalizes preexisting models in the literature and
qualitatively accounts for the experimental observed spin diffusion dynamics.Comment: Main text: 6 pages, 3 figures Supplement: 9 pages, 4 figure
Small-Angle Neutron Scattering Reveals the Structural Details of Thermosensitive Polymer-Grafted Cellulose Nanocrystal Suspensions.
Thanks to the use of small-angle neutron scattering (SANS), a detailed structural description of thermosensitive polymer-grafted cellulose nanocrystals (CNCs) was obtained and the behavior of aqueous suspensions of these derivatized biosourced particles upon temperature increase was revealed. Although literature data show that the surface grafting of thermosensitive polymers drastically enhances the colloidal properties of CNCs, direct space microscopic investigation techniques fail in providing sufficient structural information on these objects. In the case of CNCs decorated with temperature-sensitive polyetheramines following a peptide coupling reaction, a qualitative and quantitative analysis of SANS spectra shows that CNCs are homogeneously covered by a shell comprising polymer chains in a Gaussian conformation with a thickness equal to their radius of gyration in solution, thus revealing a mushroom regime. An increase of the temperature above the lower critical solution temperature (LCST) of the polyetheramine results in the formation of finite size bundles whose aggregation number depends on the particle concentration and suspension temperature deviation from the LCST. SANS analysis further reveals local changes at the CNC surface corresponding to a release of water molecules and a related denser polymer shell conformation. Noticeably, data show a full reversibility at all length scales when a sample was cooled down to below the LCST after being heated above it. Overall, the results obtained by SANS allow an in-depth structural investigation of derivatized CNCs, which is of high interest for the design of functional materials comprising these biosourced colloids.Institut Carnot PolyNat (ANR N° 16-CARN-025-01), France
Roughness Analysis In Strained Silicon-on-insulator Wires And Films
Strained silicon is used to enhance performance in state-of-the-art CMOS. Under device operating conditions, the effect of strain is to reduce the carrier scattering at the channel by a smoother semiconductor surface. This has never been completely understood. This paper gives first evidence of the variation in surface roughness under realistic strained conditions. At the nanoscale, the SiO2/Si interface roughness is dependent on the scale of observation (self-affinity). To date, there is no experimental study of the SiO2/Si interface roughness scaling with strain. This work presents the effect of uniaxial and biaxial strains on the surface roughness of strained silicon-on-insulator films and wires using atomic force microscopy. Levels of strain ranging from 0% to 2.3%, encompassing those used in present CMOS devices have been investigated. It is shown that the silicon surface is affected by uniaxial and biaxial strains differently. Three surface roughness parameters have been analyzed: root mean square roughness, correlation length, and the Hurst exponent, which is used to describe the scaling behavior of a self-affine surface. The results show that the root mean square roughness decreases (up to ∼ 40%) with increasing tensile strain, whereas the correlation length increases (up to ∼ 63nm/%) with increasing tensile strain. The Hurst exponent also varies with strain and with the undulation wavelength regime (between ∼ 0.8 and 0.2). This dependency explains why some models used to determine the carrier mobility from experiments fit the data better with a Gaussian form, whereas other models fit the data better with an exponential form.11612EPSRC; Engineering and Physical Sciences Research CouncilSong, Y., Zhou, H., Xu, Q., Luo, J., Yin, H., Yan, J., Zhong, H., (2011) J. Electron. Mater., 40, p. 1584Lee, M.L., Fitzgerald, E.A., Bulsara, M.T., Currie, M.T., Lochtefeld, A., (2005) J. Appl. Phys., 97, p. 011101Chu, M., Sun, Y.K., Aghoram, U., Thompson, S.E., (2009) Annu. Rev. Mater. Res., 39, p. 203Zhao, Y., Takenaka, M., Takagi, S., (2009) IEEE Electron Device Lett., 30, p. 987Cheng, Z.Y., Currie, M.T., Leitz, C.W., Taraschi, G., Fitzgerald, E.A., Hoyt, J.L., Antoniadas, D.A., (2001) IEEE Electron Device Lett., 22, p. 321Rim, K., Hoyt, J.L., Gibbons, J.F., (2000) IEEE Trans. Electron Devices, 47, p. 1406Fischetti, M.V., Gamiz, F., Hansch, W., (2002) J. Appl. Phys., 92, p. 7320Bonno, O., Barraud, S., Mariolle, D., Andrieu, F., (2008) J. Appl. Phys., 103, p. 063715Escobedo-Cousin, E., Olsen, S.H., Pardoen, T., Bhaskar, U., Raskin, J.-P., (2011) Appl. Phys. Lett., 99, p. 241906Pirovano, A., Lacaita, A.L., Ghidini, G., Tallarida, G., (2000) IEEE Electron Device Lett., 21, p. 34Goodnick, S.M., Ferry, D.K., Wilmsen, C.W., Liliental, Z., Fathy, D., Krivanek, O.L., (1985) Phys. Rev. B, 32, p. 8171Mazzoni, G., Lacaita, A.L., Perron, L.M., Pirovano, A., (1999) IEEE Trans. Electron Devices, 46, p. 1423Zhao, Y., Matsumoto, H., Sato, T., Koyama, S., Takenaka, M., Takagi, S., (2010) IEEE Trans. Electron Devices, 57, p. 2057Ishihara, T., Matsuzawa, K., Takayanagi, M., Takagi, S.I., (2002) Jpn. J. Appl. Phys., Part 1, 41, p. 2353Pirovano, A., Lacaita, A.L., Zandler, G., Oberhuber, R., Int. Electron Devices Meet. Tech. Dig., 1999, p. 527Yoshinobu, T., Iwamoto, A., Sudoh, K., Iwasaki, H., (1995) J. Vac. Sci. Technol. B, 13, p. 1630Mandelbrot, B.B., (1982) The Fractal Geometry of Nature: Updated and Augment, , (W. H. Freeman and Company)Pelliccione, M., Lu, T.-M., (2007) Evolution of Thin-film Morphology: Modeling and Simulations, , (Springer, Dordrecht)Zhao, Y.P., Wang, G.C., Lu, T.-M., Graef, M.D., Lucatorto, T., (2000) Characterization of Amorphous and Crystalline Rough Surface: Principles and Applications, , (Elsevier Science)Sinha, S.K., Sirota, E.B., Garoff, S., Stanley, H.B., (1988) Phys. Rev. B, 38, p. 2297Stommer, R., Martin, A.R., Geue, T., Goebel, H., Hub, W., Pietsch, U., (1999) Adv. X-Ray Anal., 41, p. 101Vicsek, T., Cserzo, M., Horváth, V.K., (1990) Physica A, 167, p. 315Arnault, J.C., Knoll, A., Smigiel, E., Cornet, A., (2001) Appl. Surf. Sci., 171, p. 189Bhaskar, U.K., Passi, V., Houri, S., Escobedo-Cousin, E., Olsen, S.H., Pardoen, T., Raskin, J.-P., (2012) J. Mater. Res., 27, p. 571Passi, V., Bhaskar, U.K., Pardoen, T., Sodervall, U., Nilsson, B., Petersson, G., Hagberg, M., Raskin, J.P., (2012) J. Microelectromech. Syst., 21, p. 822Bhaskar, U.K., Pardoen, T., Passi, V., Raskin, J.-P., (2013) Appl. Phys. Lett., 102, p. 031911Liu, X.H., Chen, J., Chen, M., Wang, X., (2002) Appl. Surf. Sci., 187, p. 187Vicsek, T., (1992) Fractal Growth Phenomena, , 2nd ed. (World Scientific)Silva, J.B.D., Jr., Vasconcelos, E.A.D., Santos, B.E.C.A.D., Freire, J.A.K., Freire, V.N., Farias, G.A., Silva, E.F.D., Jr., (2005) Microelectron. J., 36, p. 1011Liu, Z.J., Jiang, N., Shen, Y.G., Mai, Y.W., (2002) J. Appl. Phys., 92, p. 3559Gravier, S., Coulombier, M., Safi, A., Andre, N., Boe, A., Raskin, J.-P., Pardoen, T., (2009) J. Microelectromech. Syst., 18, p. 555Bunshah, R.F., (1994) Handbook of Deposition Technologies for Films and Coatings - Science, Technology and Applications, , 2nd ed. (William Andrew Publishing/Noyes)Ureña, F., Olsen, S.H., Šiller, L., Bhaskar, U., Pardoen, T., Raskin, J.-P., (2012) J. Appl. Phys., 112, p. 114506Ureña, F., Olsen, S.H., Raskin, J.-P., (2013) J. Appl. Phys., 114, p. 144507Ghyselen, B., Hartmann, J.M., Ernst, T., Aulnette, C., Osternaud, B., Bogumilowicz, Y., Abbadie, A., Mazure, C., (2004) Solid-State Electron., 48, p. 1285Lai, L., Irene, E.A., (1999) J. Appl. Phys., 86, p. 1729Schwarzenbach, W., Daval, N., Kerdilès, S., Chabanne, G., Figuet, C., Guerroudj, S., Bonnin, O., Maleville, C., (2012) Proceedings of the IEEE International Conference on Integrated Circuit Design and Technology, , (Austin, TX, USA)Xie, Y.H., Gilmer, G.H., Roland, C., Silverman, P.J., Buratto, S.K., Cheng, J.Y., Fitzgerald, E.A., Citrin, P.H., (1994) Phys. Rev. Lett., 73, p. 3006Michielis, M.D., Conzatti, F., Esseni, D., Selmi, L., (2011) IEEE Trans. Electron Devices, 58, p. 321
- …