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121.
The dynamics of molecular cluster formation from a solid bombarded by a 600 eV Ar+ ion have been studied classically by computer simulation. The dimers and trimers are found to establish their identity as clusters within interaction range of the solid, but not by a direct ejection of a bound molecule. The Cu2/Cu and Cu3/Cu ratios are found to be strongly dependent on crystal orientation. The (111) face is 2–3 times more likely to produce multimers than the (100) face. We find 9 trimers from (111) but none from (110). The relationship between cluster composition and the original arrangement of those atoms on the surface is presented in detail. We find that each multimer forms from atoms that originate within a roughly circular region of area ~70 Å2 or less. This region is not necessarily centered on the ion impact point. A consequence of this observation is that dimers can consist of atoms that were several Ångströms apart on the surface but that most trimers contain at least one nearest neighbor pair of atoms. The calculated energy distribution for the dimers matches well with similar experimental studies. 相似文献
122.
123.
Don N. Page 《Physics letters. [Part B]》1979,85(4):369-372
The Green's functions for scalar fields propagating on the self-dual gravitational multi-instantons and multi-Taub-NUT metrics are given explicitly in closed form. The special cases for flat space, Taub-NUT and the Eguchi-Hanson instanton are listed. A construction is described for obtaining the Green's functions for fields of arbitrary spin. 相似文献
124.
125.
Two atom insertions into the silacyclopropane and silacyclopropene rings: mechanistic considerations
Dietmar Seyferth Steven C. Vick Mark L. Shannon Thomas F.O. Lim Don P. Duncan 《Journal of organometallic chemistry》1977,135(2):C37-C44
Novel two atom insertion reactions into the SiC2 rings of hexamethylsilirane and 1,1-dimethyl-2,3-bis(trimethylsilyl)-1-silirene involving the C bonds of styrene and α-methylstyrene, 1,3-butadiene and its 2-methyl and 2,3-dimethyl derivatives, and, in the presence of ultraviolet radiation, of aliphatic aldehydes and ketones, are reported. A radical mechanism is suggested tobe operative in these reactions. Also described are novel palladium-catalyzed reactions of the silirene with terminal and internal acetylenes. 相似文献
126.
Jiang W Zhitenev N Bao Z Meng H Abusch-Magder D Tennant D Garfunkel E 《Langmuir : the ACS journal of surfaces and colloids》2005,21(19):8751-8757
Organic thiols have received extensive attention recently because of their relative stability and ease of examination compared to other potential molecular electronic materials. In this work, scanning probe microscopy (SPM) is used to study (i) the structural properties of self-assembled monolayers (SAMs) containing conjugated dithiols and (ii) the formation of the upper molecule-metal interface on dithiol SAMs. The top gold film is deposited either by thermal evaporation or by nano-transfer printing (nTP). Generally, the utility of thermal evaporation is limited because of Au diffusion through the SAMs. However, several dithiol SAMs are identified in this work that bond well to Au overlayers and act as satisfactory diffusion barriers. Coassembly of conjugated dithiols and alkanemonothiols is suggested as a route to obtain dithiols that are denser packed and more vertical (than is obtained from pure dithiol routes). High-yield nTP is demonstrated on coassembled SAMs. Advantages and limitations of different Au deposition and transfer techniques are compared on a variety of length scales. 相似文献
127.
Don?A.?GrundelEmail author Panos?M.?Pardalos 《Computational Optimization and Applications》2005,30(2):133-146
The multidimensional assignment problem (MAPs) is a higher dimensional version of the standard linear assignment problem. Test problems of known solution are useful in exercising solution methods. A method of generating an axial MAP of controllable size with a known unique solution is presented. Certain characteristics of the generated MAPs that determine realism and difficulty are investigated. 相似文献
128.
Dedication
Willem J. Blok 1947–2003 相似文献129.
130.
The relationship between the closed-shell repulsive interactions and overlap of the electron densities is investigated. It is found that the repulsive interactions vary in almost direct proportion to the absolute size of the density overlaps. 相似文献