Gaseous clusters number

This has important implications for nucleation in the atmosphere. Condensation of a vapor such as water to form a liquid starts when a small number of water molecules form a cluster upon which other gaseous molecules can condense. However, the size of this initial cluster is very small, and from the Kelvin equation, the vapor pressure over the cluster would be so large that it would essentially immediately evaporate at the relatively small supersaturations found in the atmosphere, up to 2% (Prup-pacher and Klett, 1997). As a result, clouds and fogs would not form unless there was a preexisting particle upon which the water could initially condense. Such particles are known as cloud condensation nuclei, or CCN. 

Agaskar et al. 28) proposed that the catalyst surface contains clusters of four active dimeric sites that can each exist in one of four states. These states differ in the number of oxygen atoms associated with them and in the oxidation state of the vanadium ions present (Figure 23). The V " " site [So] acts as an oxygen acceptor. It can either react with gaseous O2 to give... 

Lind and Bardwell have summarized the effects of radio-active materials on methane oxidation. Under the influence of the alpha radiation from radon the oxidation of methane proceeded completely to carbon dioxide and water. The oxidation took place in one step, and from the numerical relation between the number of gaseous ions produced and the methane molecules oxidized, the formation of triplet ion clusters was postulated as shown ... 

Table 2. Gaseous heats of formation, Ai/ab[AX ], for a number of Lewis acid-base AX complexes of relevance for the synthesis of cationic clusters.

For the dodecanoic acid, in contrast to 1-dodecanol, the aggregation model yields a quite high aggregation number of n = 4, while no indications exist for the formation of larger clusters. Also, no data for spread dodecanoic acid monolayers could be found in literature which exhibit characteristic inflection points in the FI-A isotherm. The dependencies at 15-20°C usually correspond to the type of gaseous monolayers [34]. Therefore, a certain similarity exists in the behaviour of fatty acids and alcohols, i.e. for a smaller number of methylene groups the system... 

When an ion exists in an ideal gaseous state, that is, when it is devoid of interactions with other particles or its surroundings in general, it is termed an isolated ion. Commonly, isolated ions consist of relatively few atoms, but some quite large ones are produced in mass spectrometers. They may also be the centers of clusters consisting of the ion proper surrounded by a small number of solvent molecules. 

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