Argon-water clusters

C. J. Tsai and K. D. Jordan, Use of an eigenmode method to locate the stationary points on the potential-energy surfaces of selected argon and water clusters. J. Phys. Chem. 97(43), 11227-... 

S. Hirabayashi, K.M.T. Yamada, Infrared spectra and structure of water clusters trapped in argon and krypton matrices. J. Mol. Struct. 795(1-3), 78-83 (2006)... 

Ethynylhydroxy carbene [13] has been obtained by photoreaction (A>400 nm) of a triatomic carbon cluster with water in an argon matrix and studied by IR spectroscopy (Ortman et al., 1990). Five frequencies were measured for [13] and a vibrational band at 1999.8 cm has been assigned to the C=C stretch. This value is more than 100 cmlower than the C=C stretching vibrations in acetylene derivatives, indicating that the C=C bond in the carbene [13] has lost some of its triple bond character. At the same... 

Nishi and coworkers (Shinohara et al. 1985, 1986) have reported the production of unprotonated water and ammonia cluster ions, as well as Ar X+ (X = H20 and NH3) cluster ions when argon/molecule mixed expansions were ionized using UV lines from an argon lamp. The quenching of the proton transfer reaction was attributed to the cooling of the heterocluster ions via... 

Coupling pulse radiolysis with time-resolved spectroscopy also allowed the determination of the transient absorption spectra of hydrated silver atom and of the first silver clusters showing that the absorption properties of silver atoms and metal aggregates in solution are different from that of bare clusters in gas phase. Silver atom presents an absorption maximum at 360 nm in water,while it absorbs at substantially shorter wavelengths in argon (292-310 nm) or in xenon (322-333 nm) atmosphere. ... 

Radiolysis has been used successfully in order to synthesize various noble (such as silver, gold and platinum) and non-noble (such as nickel and iron) metal nanoparticles in aqueous solution and also in other solvents such as alcohols. Due to their relatively low redox potential compared to that of the bulk, metal clusters can be oxygen-sensitive. However, the deoxygenation (by bubbling with an inert gas such as argon or nitrogen) of the solutions prior to irradiation and their study under inert atmosphere prevent their oxidation. Moreover, since water radiolysis leads to the formation of protons in addition to that of hydrated electrons, radio-induced acidification of the medium may lead to non-noble metal clusters corrosion. Therefore, to avoid the oxidation by protons, the solutions can be prepared in slightly basic medium. 

Van der Waals complexes were observed between two molecules of 1,2,4,5-tetrazine (la) and helium, argon, krypton, xenon, hydrogen, water, hydrochloric acid, acetylene or benzene 28 36- 396-420 jn coi,j environment of a jet expansion. In favorable systems it has been possible to determine the ground and excited state geometry of the cluster by laser spectroscopy. From these structures, it has been found that 1,2,4,5-tetrazine possesses a number of different binding sites. Helium and argon bind to the equivalent sites above and below the ring.28-30 The predominant interaction in these clusters is presumably the attractive dispersion force. 

The interaction energies of clusters of molecules can be decomposed into pair contributions and pairwise-nonadditive contributions. The emphasis of this chapter is on the latter components. Both the historical and current investigations are reviewed. The physical mechanisms responsible for the existence of the many-body forces are described using symmetry-adapted perturbation theory of intermolecular interactions. The role of nonadditive effects in several specific trimers, including some open-shell trimers, is discussed. These effects are also discussed for the condensed phases of argon and water. 

Fig. 18. Vibrational spectra of the Br (H20)3 Aro,i,3 clusters (a) without Ar, predissociation by loss of one water, (b) with one argon, predissociation by loss of argon, (c) with three argons, predissociation by loss of argon. The cooling of the cluster ions by the presence of argon is quite apparent, but does not depend on the number of argons. ...

Binder and Stauffer have calculated Monte Carlo average surface energies of cubic clusters of a lattice gas. When their data for clusters of up to 256 atoms are plotted in the same form as we did before for argon and water (Fig. 13), we see the surface energy of these lattice gas clusters is well described by Eq. (50). 

Remarkably few isolable complexes exhibit silver-silver covalency. The ionization potential [144] and bond length (2.5310(10) A) [145] of singly bonded Ag-Ag have been determined by spectroscopic studies on supersonic beams. Small clusters Ag ( = 2-5) have been synthesized and studied in an argon matrix [146], and the gas-phase synthesis and reaction chemistry of mixed-valent silver(0/I) clusters have been studied by mass spectrometry [147]. Pulse radiolysis of Ag+ solutions or glasses in water and ethanol has allowed the study of unstable clusters as intermediates in metal colloid formation thus, the absorption and EPR spectra of [Ag2], [Ag4], and [Ag4] have been recorded [148]. These are fully delocalized Ag(0,I) ions in which partial occupation of silver 5s-orbital combinations leads to net metal-metal bonding. 

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