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Ruoyu Hong * Jianmin Ding Guoliang Zheng College of Chemistry Chemical Engineering Soochow University Suzhou P. R. China Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China IBM HYDA/- C Highway North Rochester MN USA *Author to whom correspondence should be addressed. E-mail: rhong@suda.edu.cn 《中国颗粒学报》2004,2(5):207-214
1. Introduction1.1 Silica nanoparticles and synthesis methods Silica (SiO2) nanoparticles are widely used in industry asan active filler for polymer reinforcement, a rheologicaladditive in fluids, a free flow agent in powders, and anagent for chemical mechanical polishing during IC (inte-grated circuit) fabrication (Sniegowski & de Boer, 2000).Silica powder is also used for producing silicon carbide(Koc & Cattamanchi, 1998) or opaque silica aerosols (Leeet al., 1995). Many methods can … 相似文献
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K.A. Geoffroy J.B. Natowitz R. Eggers P. Kasiraj M.N. Namboodiri 《Nuclear Physics A》1978,302(1):333-342
The emission of prompt γ-radiation in the de-excitation of the products of the reactions of 120 MeV 20Ne with 27Al has been studied. Three NaI detectors placed at angles of 35°, 90° and 145° to the direction of the 20Ne beam were used to detect γ-rays in coincidence with reaction products having 6 ≦ Z ≦ 20, detected in a counter telescope. Data were obtained with the counter telescope in the same plane, as well as in a plane perpendicular to the plane defined by the beam and the NaI detectors. The average multiplicities 〈Mγ〉, average energies 〈Eγ〉, primary γ-ray energy spectra and the variation of 〈Mγ〉 and 〈Eγ〉 with angle of observation and kinetic energy of the detected products are presented and discussed in terms of the dominant reaction mechanisms. 相似文献
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M.N. Namboodiri P. Gonthier H. Ho J.B. Natowitz R. Eggers L. Adler P. Kasiraj C. Cerruti A. Chevarier N. Chevarier A. Demeyer 《Nuclear Physics A》1981,367(2):313-332
The emission of H and He isotopes in the reactions of 120 MeV 20Ne with 27A1 has been studied using light particle-heavy ion coincidence measurements. The energy spectra and angular correlations of the light particles emitted in coincidence with products of agree well with the predictions of the statistical model applied to the decay of the compound nucleus 47V. Results on α-particle emission associated with deep inelastic reactions leading to carbon and oxygen products are also reported. 相似文献
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P.L. Gonthier H. Ho M.N. Namboodiri J.B. Natowitz L. Adler S. Simon K. Hagel S. Kniffen A. Khodai 《Nuclear Physics A》1983,411(2):289-328
Inclusive energy spectra and angular distributions for heavy ions produced in the reactions of 227 MeV and 310 MeV 16O with Ti were measured. Also measured at the projectile energy of 310 MeV were energy and angular correlations between light charged particles (Z ≦ 2) and heavy ions. From comparisons with statistical model calculations upper limits to the complete fusion cross sections of 647 mb and 265 mb were derived for projectile energies of 227 MeV and 310 MeV, respectively. At 310 MeV the cross section of incomplete fusion processes was estimated to be over 505 mb. Emission of fast, high-energy α-particles and protons was observed to be a characteristic feature of quasi-elastic, deep-inelastic and fusion-like reactions. Average multiplicities of fast light particles in coincidence with heavy ions at +20° and +40° were estimated to be of the order of 1. The prompt emission of light appears to be the principal mechanism which limits complete fusion. A second component of α-particles observed in coincidence with deep-inelastic projectile-like fragments and having an energy comparable to Coulomb energies of particles emitted from target-like and projectile-like fragments appears as an excess yield in the direction of the recoiling target-like fragments. This component cannot be accounted for in terms of sequential emission processes and may result from a mechanism other than the one which leads to fast particle emission. 相似文献
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Konradi J Gaal A Scaria A Namboodiri V Materny A 《The journal of physical chemistry. A》2008,112(7):1380-1391
Femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) gives access to ultrafast molecular dynamics. However, the gain of the temporal resolution entails a poor spectral resolution due to the inherent spectral width of the femtosecond excitation pulses. Modifications of the phase shape of one of the exciting pulses results in dramatic changes of the mode distribution reflected in coherent anti-Stokes Raman spectra. A feedback-controlled optimization of specific modes making use of phase and/or amplitude modulation of the pump laser pulse is applied to selectively influence the anti-Stokes signal spectrum. The optimization experiments are performed under electronically nonresonant and resonant conditions. The results are compared and the role of electronic resonances is analyzed. It can be clearly demonstrated that these resonances are of importance for a selective excitation by means of phase and amplitude modulation. The mode selective excitation under nonresonant conditions is determined mainly by the variation of the spectral phase of the laser pulse. Here, the modulation of the spectral amplitudes only has little influence on the mode ratios. In contrast to this, the phase as well as amplitude modulation contributes considerably to the control process under resonant conditions. A careful analysis of the experimental results reveals information about the mechanisms of the mode control, which partially involve molecular dynamics in the electronic states. 相似文献
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Scaria A Namboodiri V Konradi J Materny A 《Physical chemistry chemical physics : PCCP》2008,10(7):983-989
By using a combination of an initial pump pulse and a degenerate four-wave mixing process, we show that an interrogation of the vibrational dynamics occurring in different electronic states of molecules is possible. The technique is applied to iodine. The initial pump pulse is used to populate the B((3)Pi) state of molecular iodine in the gas phase. Now, by using an internal time delay in the DFWM process, which is resonant with the transition between the B state and a higher lying ion-pair state, the vibrational dynamics of the B state and the ion-pair state could be observed. States of even symmetry are investigated, which are accessed by a one photon transition from the B state. By a proper choice of the wavelengths used for the pump and DFWM beams, the dynamics of ion-pair states belonging to two different tiers are monitored. 相似文献
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Superlubricity of graphite 总被引:1,自引:0,他引:1
Dienwiebel M Verhoeven GS Pradeep N Frenken JW Heimberg JA Zandbergen HW 《Physical review letters》2004,92(12):126101
Using a home-built frictional force microscope that is able to detect forces in three dimensions with a lateral force resolution down to 15 pN, we have studied the energy dissipation between a tungsten tip sliding over a graphite surface in dry contact. By measuring atomic-scale friction as a function of the rotational angle between two contacting bodies, we show that the origin of the ultralow friction of graphite lies in the incommensurability between rotated graphite layers, an effect proposed under the name of "superlubricity" [Phys. Rev. B 41, 11 837 (1990)]]. 相似文献
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Akiba Y Beavis D Beery P Britt HC Budick B Chasman C Chen Z Chi CY Chu YY Cianciolo V Cole BA Costales JB Crawford HJ Cumming JB Debbe R Engelage J Fung SY Gonin M Gushue S Hamagaki H Hansen O Hayano RS Hayashi S Homma S Kaneko H Kang J Kaufman S Kehoe WL Kurita K Ledoux RJ Levine MJ Miake Y Morrison DP Morse RJ Moskowitz B Nagamiya S Namboodiri MN Nayak TK Olness J Parsons CG Remsberg LP Roehrich D Rothschild P Sakurai H Sangster TC Seto R Soltz R Stankus P Steadman SG Stephans GS Sung T 《Physical review letters》1996,76(12):2021-2024