Cluster growth monitoring

The formation-growth of gold clusters was monitored by UV-Vis spectroscopy, by looking at the very intensive surface plasmon absorption characterizing nano-sized gold. Optical spectra were recorded at different reaction... 

An inverted version of the messenger tagging technique for detecting ion absorption uses the fact that electronic and/or vibrational excitation of ions hinders formation of weakly-bound clusters. This effect, explored years ago in relation to laser isotope separation [82], has recently been demonstrated for spectroscopy of N2" ions, cooled to 10.6 K in a 22-pole trap by collisions with He and termed laser-induced inhibition of cluster growth (LIICG) [83]. An electronic spectrum is generated by monitoring the reduction of the steady-state concentration of ion-He complexes as a function of the excitation laser wavenumber. 

Ishii, K., Iwai, T., Monitoring of the Cluster Growth in the Colloidal Suspension Using a Diffusive-Wave Speetroseopie Teehnique, Proc. SPlE-lnt. Soc. Opt. Eng., 1999, 3599,16-85. 

Supported model catalysts are frequently prepared by thermally evaporating metal atoms onto a planar oxide surface in UHV. The morphology and growth of supported metal clusters depend on a number of factors such as substrate morphology, the deposition rate, and the surface temperature. For a controlled synthesis of supported model catalysts, it is necessary to monitor the growth kinetics of supported metal... 

Although STM is not a particularly fast observation technique, the growth of a metal cluster can still be monitored during its initial stages, provided the growth rate is slowed down by appropriate experimental parameters, such as overpotential and electrolyte composition. In addition, the interference of the STM tip with electro-... 

Fig. 19. X-t scan of an STM, monitoring the growth of an individual Cu cluster on Au(l 11) at —0.18 V vs. Cu/Cu++ over a period of about 2 min. Formation of 14 monolayers are seen. Electrolyte 0.5 M H2S04 + 5 mM CuS04 [43],...

Bacterial leaching, minerals, 36 115-121 laboratory reactors, 36 116-117 monitoring organism growth, 36 117-119 nutrient effects, 36 119 pH control, 36 121 toxicity effects, 36 119 Bacterioferritin, see also Bacfer cluster, 43 362-363... 

Controlled reduction of cadmium (or lead) ions on surfaces of nanosized silver (or gold) metallic particles results in the formation of double-layer colloids [532-534]. Depending on the coverage, the second layer can vary from being non-metallic clusters to quasi-metallic and metallic colloids. Growth of the second-layer particles can be monitored by absorption spectrophotometry. For... 

Pt-Re First moments of formation of bimetallic cluster monitored. Controlled by A1203 network initially. Metal segregation occurs later after particle growth.35 ... 

Summary. Surface-enhanced Raman spectrsocopy (SERS) can be used as an in-situ method for monitoring the development of surface morphology, nucleus formation, and crystal growth. The correlation between the true surface area and the Raman intensity was investigated. The splitting of the CN stretch vibration is interpreted as a representation of a surface cluster distribution. 

The couple S/S is selected with a specific and intense optical absorption of S or S , so that the electron-transfer reaction can be observed directly. In the early stages of atom coalescence, the redox potentials of the atom and of the smallest clusters are generally far below that of the donor and the transfer from S to the oligomer does not occur. The ion reduction is caused exclusively by solvated electrons and alcohol radicals (Eqs. 2, 8, and 9). The nucleation and coalescence dynamics are thus the same as in the absence of (Eqs. 10 and 11). Beyond a certain critical time, tc, that is large enough to enable the growth of clusters and the increase of their potential above the threshold imposed by the electron donor S , electron transfer from this monitor to the supercritical clusters is allowed (Eq. 32) and detected by the absorbance decay of S (Fig. 6). For n > ny. 

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