Adjacent pair

The dangling bonds of a Si surface abstract one F atom from an incident F2 molecule while the complementary F atom is scattered back into the gas phase [20]. This abstractive mechanism leads to F adsorjDtion at single sites rather than at adjacent pairs of sites, as observed directly by scanning tunnelling microscopy [21]. Br atoms adsorb only to Ga atoms in the second layer of GaAs(001)-(2 x 4) where empty dangling bonds on the Ga atoms can be filled by electrons from the Br atoms [22]. 

If a contour in a given plane surrounds two conical intersections belonging to two different (adjacent) pairs of states, only two eigenfunctions flip sign—the one that belongs to the lowest state and the one that belongs to the highest one. 

Separable (balanced-opposed) frames are characterized by an adjacent pair of crank throws 180° out of phase. The frame is separate from the... 

FIGURE 17.5 The structure of an axoneme. Note the manner in which two microtubules are joined in the nine outer pairs. The smaller-diameter tubule of each pair, which is a true cylinder, is called the A-tubule and isjoined to the center sheath of the axoneme by a spoke structure. Each outer pair of tubules isjoined to adjacent pairs by a nexin bridge. The A-tubule of each outer pair possesses an outer dynein arm and an inner dynein arm. The larger-diameter tubule is known as the B-tubule. 

There are numerous examples of chemical reactions consequent upon chemical groups which occur repeatedly along a chain. In some cases the reaction occurs randomly between adjacent pairs of groups such as in the reaction between aldehydes and polyvinyl alcohol and of zinc dust with polyvinyl chloride ... 

The resonating-valence-bond theory of the electronic structure of metals is based upon the idea that pairs of electrons, occupying bond positions between adjacent pairs of atoms, are able to carry out unsynchronized or partially unsynchronized resonance through the crystal.4 In the course of the development of the theory a wave function was formulated describing the crystal in terms of two-electron functions in the various bond positions, with use of Bloch factors corresponding to different values of the electron-pair momentum.5 The part of the wave function corresponding to the electron pair was given as... 

Where peak dispersion has not been constrained to very small volumes the external sample loop injector can be used and the external loop sample system, which employs six ports, is depicted in figure 15. In the external loop sample valve, three slots are cut in the rotor so that any adjacent pair of ports can be connected. In the loading position shown on the left, the mobile phase supply is connected by a rotor slot to port (4) and the column to port (5) thus allowing mobile phase to flow directly through the column. In this position the sample loop is connected to ports (3) and (6). Sample flows from a syringe into port (1) through the rotor slot to the sample loop at port (6). At the same... 

Table 4.1 Molecular weight of horse heart myoglobin calculated from four adjacent pair of ions observed in its electrospray mass spectrum...

For this case, x,d are unknown for the components between the keys. The values of 6 obtained from Equation 9.50, where each 6 lies between an adjacent pair of relative volatilities. Once the values of 6 have been determined, Equation 9.51 can be written for each value of 6 with x,d of the components between the keys as unknowns. This set of equations is then solved simultaneously for Rmin and x, d for the components between the keys. 

The many higher boranes such as B5H9 and BgH 2 are similarly electron deficient and cannot be described by a single Lewis structure. They can often be described in terms of a combination of two- and three-center bonds. Alternatively, their structures can be rationalized by electron-counting schemes such as those proposed by Wade. Analysis of the electron density of these molecules by the AIM method shows that there are bond paths between all adjacent pairs of atoms. So from the point of view of the AIM theory there are bonds between each adjacent pair of atoms, but these cannot all be regarded as Lewis two-center, two-electron bonds as is the case in B2H6. 

Ring closure between an adjacent pair of aromatic substituents is also possible an example is the formation of indan from l-methyl-2-ethyl-benzene 11,109). In fact, Csicsery 109) found that the rate of cyclization of l-methyl-2-ethylbenzene to indan over platinum was somewhat faster than that of n-butylbenzene to methylindan, indicating that kinetically there is nothing to be gained by having ring closure at an aromatic carbon... 

The initial step is an oxidative addition of RhCI(PPh3)3 to a C-0 bond of the ester moiety and produces rhodium-carbon and rhodium-oxygen bonds. Adjacent rhodium species can undergo further reaction with the formation of anhydride linkages. This anhydride formation may occur between adjacent pairs of reactants, between pairs in the same chain, or between pairs that are present in different chains. All of these reactions are observed, and in however the last reaction is the one of interest here since this leads to cross-linking and char formation. Rhodium is present in both the chary material and in the soluble fractions. From the reaction pathway in order for rhodium elimination to occur, two rhodium-inserted... 

However, comparisons such as (5.54a)-(5.54e) cannot yet be used for direct estimation of the formal non-additivity (5.52), because they neglect the contributions of 0 -adjacent pairs in (5.51). Table 5.19 summarizes details of the individual V(A, B) contributions and non-pairwise errors (%npw) for two of these cases the... 

The layer stacking is synclinic in the tilt plane and antiferroelectric in the polar plane. The phase composed of an infinite number of SmCP layers stacked in this way is termed SmCsP, where the subscripts S and A each refer a structural feature of the layer interfaces between adjacent pairs of layers. If two adjacent layers are tilted in the same direction, the interface is synclinic (subscript S) in the tilt plane. If two adjacent layers have antiparallel orientation of their polar axes, then the layer interface is said to be antiferroelectric (A) in the polar plane. 

Single-phase operation moves the rotor from 0°, to 90°, to 180°, to 270°, and to 360°, whereas the two-phase mode uses adjacent pairs of electromagnets so that rotor comes to a balance point between them, pulling the rotor from 45°, to 135°, to 225°, and to 315°. With pairs of electromagnets activated, the torque is increased. The half-step mode is a combination of both single phase and two phase, pulling the rotor from... 

Fig. 4. Adjacent genes with conserved relative transcription orientation versus evolutionary distance. The plot shows the fraction of conserved gene pairs with the same relative direction of transcription between two species. Shown are pairs with a single direction of transcription, pairs with a divergent direction of transcription, and pairs with a convergent direction of transcription. The X axis represents the small subunit rRNA distance between the species (Fig. 3). The number of conserved adjacent pairs declines nonlinearly with phylogenetic distance and was therefore depicted on a logarithmic scale. Note that the vast majority of conserved adjacent pairs with a conserved relative transcription orientation are transcribed in the same direction. Divergently transcribed pairs are better conserved than convergently transcribed ones, hinting at the conservation of divergent promotors.

For the various "indices of complexity" which have been proposed and the minimum requirements they must meet in order to be really useful, see Bertz [30a]. The "complexity index" r], proposed by Bertz, is based on the number of connections and is defined as the number of adjacent pairs of bonds existing in one molecule. 

To build up a "bond graph", the bonds of a given molecule are enumerated and represented by a point, and then each pair of points is connected with a line whenever the corresponding bonds are adjacent. Therefore, the number of the resulting lines gives the number of "adjacent pairs" or connections (t)). For example,... 

Lamola and Eisinger169 have shown that the oriented adjacent pairs of 1,3-dimethyl-thymine monomers formed by photosplitting of the appropriate dimer in frozen solution will photodimerize again with a quantum yield of close to unity, and that the pair of monomers shows no fluorescence, but an exciton splitting in the absorption spectrum. 

The transitions in the X-band ESR spectra of triplet species occur in two regions. The so-called Anis = 1 region represents transitions between energetically adjacent pairs of the three triplet sublevels. These are characterized by two so-called zero-field splitting parameters, D and E. The parameter D is inversely proportional to the cube of the average separation of the electron spins, and E is related to the molecular symmetry. The number of lines depends on the molecular symmetry. If all three magnetic axes of the molecular carrier of the spectrum are distinct, the spectrum in the Anis = 1 region will show six major resonances, plus any hyperfine lines that may be visible. If two of the principle axes are equivalent by symmetry, only four lines will be observed. In the latter case, the parameter E has the value of... 

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