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131.
Tiberius E. Braun 《Mikrochimica acta》1957,45(1):128-130
Sans résumé 相似文献
132.
H. Braun 《Applied Physics A: Materials Science & Processing》1978,17(2):193-197
The electrical conductivity of a conducting powder is influenced by the properties of the grain surface as well as the grain
core. By appropriate variation of pressure and electric frequency, the two contributions can be separated, as long as the
grains have shapes nearly like spheres. From experimental data on pressed powders one can thus obtain information concerning
carrier density and mobility of bulk material. Results for PbO2 obtained in this way agree well with the properties of bulk PbO2 samples reported in the literature. 相似文献
133.
Augustin Van Groenendael Jacques Tillieu 《International journal of quantum chemistry》1985,28(2):269-286
We adapt the use of the Lie algebra su (n) we proposed in former papers to a system made up of two subsystems (respectively, nA and nB states). We show how reduced density operators, correlation problems, and overall and reduced evolution equations, may be made precise with this formalism. 相似文献
134.
135.
Experiments using atomic force microscopy for unfolding single multidomain biopolymers cover a broad range of time scales
from equilibrium to non-equilibrium. A master equation approach allows to identify and treat coherently three dynamical regimes
for increasing linear ramp velocity: i) an equilibrium regime, ii) a transient regime where refolding events still occur,
and iii) a saw-tooth regime without any refolding events. For each regime, analytical approximations are derived and compared
to numerically investigated examples. We analyze in the framework of this model also a periodic experimental protocol instead
of a linear ramp. In this case, a major simplification arises if the dynamics can be restricted to an effectively two-dimensional
subspace. For transitions with an intermediate meta-stable state, like Immunoglobulin27, a refined model allows to extract
previously unknown molecular parameters related to this meta-stable state. 相似文献
136.
J.?Bartels M.?Braun G.?P.?VaccaEmail author 《The European Physical Journal C - Particles and Fields》2005,40(3):419-433
We analyze the momentum space triple pomeron vertex in perturbative QCD. In addition to the standard form of this vertex which is used in the context of total cross sections at high energies and in the QCD reggeon field theory, there exists an alternative form which has to be used in the study of high-mass diffraction. We review and analyze the relation between these two versions. We discuss some implications for the BK equation. In the second part of our paper we extend this analysis to the pomeron-odderon-odderon vertex.Received: 11 January 2005, Revised: 24 January 2005, Published online: 3 March 2005 相似文献
137.
Eckhoff DA Sutin JD Clegg RM Gratton E Rogozhina EV Braun PV 《The journal of physical chemistry. B》2005,109(42):19786-19797
Studying the properties and stability of silicon nanoparticles (Si-np) in aqueous environments may lead to novel applications in biological systems. In this work, we use absorption and photoluminescence (PL) spectroscopy to characterize ultrasmall Si-np prepared through anodic etching and ultrasonic fractionation of a crystalline Si wafer. Their behavior is studied over time in 2-propanol and during treatments with water, NaOH, HCl, and H(2)O(2). The observed population is divided into two types of material: bright species consisting of well-etched Si-np, approximately 1 nm in diameter, and dark species derived from partially etched or aggregated Si structures. The dark material is seen by its scattering in the 2-propanol and water solutions and is largely removed via precipitation with the NaOH or HCl treatment. The bright material includes three distinct species with their respective emissions in the UV-B, UV-A, and hard-blue regions of the spectrum. The hard-blue PL is shown to have a simple pH dependence with a pK(a) approximately 3, providing an important insight into its chemical origin and signaling for possible application of Si-np as environmental probes. Our results offer some potential for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry. 相似文献
138.
Consider a singularly perturbed equation of the form
(1) 相似文献
139.
We have investigated the formation and motion of copper adatoms and addimers on Ag(111) between 6 and 25 K with low-temperature scanning tunneling microscopy. The presence of atoms and dimers alters the motion of atoms and dimers via the long-range interaction mediated by the electrons in the two-dimensional surface state band. Above 16 K, dimers show quantum rotor behavior with altered rotational behavior in the presence of an additional adatom. The most favorable diffusional motion of the dimer is identified in combination with molecular dynamics calculations to be a zigzag out-of-cell motion starting above 24 K. 相似文献
140.
A novel scanning tunneling microscope manipulation scheme for a controlled molecular transport of weakly adsorbed molecules is demonstrated. Single sexiphenyl molecules adsorbed on a Ag(111) surface at 6 K are shot towards single silver atoms by excitation with the tip. To achieve atomically straight shooting paths, an electron resonator consisting of linear standing-wave fronts is constructed. The sexiphenyl manipulation signals reveal a pi ring flipping as the molecule moves from the hcp to fcc site. Ab initio calculations show an incorporation of the Ag atom below the center of a pi ring. 相似文献