Attraction, interactions between

Fig. 4. Atom manipulation by the scanning tunneling microscope (STM). Once the STM tip has located the adsorbate atom, the tip is lowered such that the attractive interaction between the tip and the adsorbate is sufficient to keep the adsorbate "tethered" to the tip. The tip is then moved to the desired location on the surface and withdrawn, leaving the adsorbate atom bound to the surface at a new location. The figure schematically depicts the use of this process in the formation of a "quantum corral" of 48 Fe atoms arranged in a circle of about 14.3 nm diameter on a Cu(lll) surface at 4 K.

However, we also need to discuss how the attractive interactions between species can be included in the theory of partly quenched systems. These interactions comprise an intrinsic feature of realistic models for partially quenched fluid systems. In particular, the model for adsorption of methane in xerosilica gel of Kaminsky and Monson [41] is characterized by very strong attraction between matrix obstacles and fluid species. Besides, the fluid particles attract each other via the Lennard-Lones potential. Both types of attraction (the fluid-matrix and fluid-fluid) must be included to gain profound insight into the phase transitions in partly quenched media. The approach of Ford and Glandt to obtain the chemical potential utilizing... 

A full description of how a reaction occurs is called its mechanism. There are two general kinds of mechanisms by which reactions take place radical mechanisms and polar mechanisms. Polar reactions, the more common type, occur because of an attractive interaction between a nucleophilic (electron-rich) site in one molecule and an electrophilic (electron-poor) site in another molecule. A bond is formed in a polar reaction when the nucleophile donates an electron pair to the electrophile. This movement of electrons is indicated by a curved arrow showing the direction of electron travel from the nucleophile to... 

The friction from the repulsive pinning center is of particular interest because it is contrary to the common belief that friction must result from attractive interactions between sliding surfaces. The results presented in Fig. 17(a) demonstrate that friction can be created by purely repulsive interactions. What really matters is the instability of the sliding body and energy dissipation, rather than the attractive or repulsive nature of interactions. This may also shed a light on the efforts to explore the correlation between friction and adhesion. 

Schmidbaur, H., Graf W. and Muller, G. (1988) Weak Intramolecular Bonding Relationships The Conformation-Determining Attractive Interaction between Gold(I) Centers. Angewandte Chemie International Edition, 27,... 

Other studies have also established the preference of the chair conformation with the oxygen in the axial position the rationale for this preference is different from the attractive interaction between the sulfoxide oxygen and the syn-axial hydrogens proposed previously . Rather, a repulsion effect is advocated the equatorial oxygen is squeezed between four vicinal hydrogens, while there are only two corresponding repulsions if it is in the axial position. The correlation between the predicted and observed conformational/orientational preferences in 3,3-dimethylthiane oxide (e.g., equatorial preference in the chair conformation) corroborates this interpretation. The axial preferences of the sulfur-oxygen bond in the thiane oxide is reversed in 3,3-dimethylthiane oxide because of the syn-axial interaction. 4,4-Dimethylthiane oxide, however, maintains a predominance of the axial isomers as deduced from the analysis of NMR data . ... 

The hydrogen bond is an attractive interaction between a group X-H and an atom or a group of atoms, in the same or different molecule(s), when there is evidence of bond formation. ... 

In any state preceding the onset of crystallization at T < To we assume that bundle stability is favored by localized attractive interactions between contacting (short) stems, some enthalpy advantage being balanced by a corresponding entropy loss (see Fig. 3). Depending upon the core structure of the crystalline stems, various bundle models were examined [8,9]. In the present... 

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