Competitive cryochemical reactions of transition metal atoms, clusters and nanosized particles

Synthesis and characterization of gallium colloidal nanoparticles

“…These bands appear between 809 and 820 cm À1 [49]. It is probable that the t (GaAO) is overlapped with GaAC vibrations, because to GaAO vibrations appear between 590 and 563 cm À1 [50]. We consider that this last absorption corresponds to the interaction of the gallium with water molecules coming from environmental moisture, due to the 1605 cm À1 interaction typical of the water absorption.…”

“…It was also observed that the absorption decrease as a function of time, due to the high reactivity of the surface of the Ga nanoparticles, which intend to produce fractal aggregates [31,32]. These, in turn, flocculate due to gravitational effects, thereby reducing the absorption.…”

“…The increase in the amount of nanoparticles in suspension reduced the distance among particles, which allows the attractive forces to prevail over the repulsive forces responsible for colloid stability. Attractive forces decrease the zeta potential and the electrophoretic mobility, and so permitting interaction among the nanoparticles, forming fractal aggregates [31]. These grow in size until the effects of gravity are considerable and the aggregates flocculate.…”

“…A glass device with organic solvent (2-propanol, acetone and THF p.a. grade, purchased from Fisher), dried with molecular sieves and further degasified three times by standard freeze-thaw procedure [31] was attached to the neck of the reactor. The whole system was immersed in liquid nitrogen (77 K) and evacuated on reaching a vacuum of 10 À5 bars.…”

Metal Coordination ofCO2

“…No Cu(CO 2 ) complex was found, but a weak η 1 O-Cu 2 (OCO) interaction was calculated to exist, suggesting that the species experimentally observed in matrices was in fact a Cu 2 end-on complex. 62 The formation of OCuCO − anions was observed with laser-ablated Cu atoms by Andrews et al, 52 produced by the addition of Cu to CO 2 − ; the latter was formed by electron capture in the experiments.…”