Cluster formation, mechanism

Figure 13 shows the sputtering power dependence of cluster size. It can be seen that FePt, CoPt cluster size has a nearly linear relationship with the sputtering power of the cluster source. It is noted that the cluster size follows a Gaussian distribution rather than a lognormal one as observed in Fe clusters [31]. This may be related to the cluster formation mechanism involved in the present method, which is different from the mechanisms for lognormal distribution. A similar Gaussian distribution was also reported in CoAl clusters [40]. 

Another important application to photography of our understanding of the cluster formation mechanism in radiation chemistry is the enhancement of the sensitivity of photographic emulsions (Fig. 11) [16]. The primary effect ofthe photon absorption by the silver halide crystals of the emulsion during the exposure is indeed to produce one... 

StiU another possible role of supersaturation is that it affects the solution stmcture and causes the formation of clusters of solute molecules. These clusters may participate in nucleation, although the mechanism by which this would occur is not clear. Evidence of the existence of cluster formation in supersaturated solutions has been presented for citric acid (21) while others have examined the phenomenon in greater detail (22,23). 

Laine and co-workers have studied the mechanism involved in rhodium-catalysed benzaldehyde hydrogenation, using [Rh6(CO)i6] as catalyst precursor. Following kinetic arguments, the authors proposed cluster catalysis with a limiting step corresponding to the break of metal-metal bond and/or isomerisation of the cluster formation [22]. 

Thus, there is literature showing the formation of clusters and some of the potential interactions that occur in the air. However, there has not been a systematic study of the mechanisms of cluster formation and the possible interactions of various common atmospheric species in that process. 

Diaza-OTdo-hexaboranes [N2B4R4R 2] are the products of the fusion of rings NB2R2R. The mechanism of this cluster formation was investigated and in the case of the neopentyl substituent (R = CH2/Bu, R = /Bu) a tetracyclic molecule was identified as a possible intermediate in the ring fusion reaction.81,8111... 

The chemistry and formation of a variety of substitution patterns of the cluster (NHR)B8FIn(NH2R) was studied extensively in the last 10 years.83,91-94 Furthermore, the electron count was discussed hypho-nine-vertex cluster, zzrar 0-eight-vertex versus -eight-vertex cluster.95,96 The formation mechanism of this azaborane and espe-... 

Karas, M. KriigCT, R. Ion Formation in MALDI The Cluster Ionization Mechanism. Chem. Rev. 2003,103,427-439. 

While Pb is typically not a useful choice for device top contacts because of its low melting point and soft mechanical characteristics, it is of considerable interest for its superconducting characteristics. There appear to be, however, no reports on Pb deposition on SAMs. In our own preliminary experiments of Pb deposition on Cl6 alkanethiolate SAM on Au/mica from UHV AFM imaging, we observed complete penetration with no top surface cluster formation and continuing penetration into the underlying Au lattice. ... 

The setup used in these experiments is remarkably simple all that is required is a mechanical vacuum-feedthrough by which a rotatable rod, made of or topped by the desired material, can be introduced. Pulses of the fundamental of a Q-swiched, pulsed Nd Yag laser (typically 20-80 mJ/pulse, 1-10 Hz) are focused on that target, either through a separate port, or simply from behind the cold window.In order to avoid formation of pits that lead to a greater propensity for cluster formation, the rod is rotated slowly such as to expose a fresh surface to successive laser pulses. ... 

A classical dynamics model is used to investigate nuclear motion in solids due to bombardment by energetic atoms and ions. Of interest are the mechanisms of ejection and cluster formation both of elemental species such as Nin and Arn and molecular species where we have predicted intact ejection of benzene-CgHg, pyridine-Cs N, napthalene-CigHg, bipheny 1-0 2 10 an[Pg.43]

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