Nucleation condensation energy

Gas Solid S/G Adsorption, catalysis, corrosion, oxidation, diffusion, surface states, thin films, condensation and nucleation, permeation, energy transfer. 

Depending on the protein, the free energy landscape differs as is illustrated in Fig. 6. For some two-state proteins, with an independently stable secondary structure, the diffusion-collision mechanism is preferred. Other proteins,for which the secondary structure is less stable on its own, fold cooperatively using the nucleation-condensation pathway. In all cases there is still two state behavior, because there is only one rate limiting barrier. 

Figure 1.9 The balance of endothermic surface energy and the exothermic formation of the stable condensed phase during nucleation from the vapour phase. The critical radius, above which the nuclei become stable, is where the resultant Gibbs energy change has zero slope...

Having described the equilibrium structure and thermodynamics of the vapor condensate we then re-examine homogeneous nucleation theory. This combination of thermodynamics and rate kinetics, in which the free energy of formation is treated as an activation energy in a monomer addition reaction, contains the assumption that equilibrium thermodynamic functions can be applied to a continuum of non-equilibrium states. For the purpose of elucidating the effects of the removal of the usual approximations, we retain this assumption and calculate a radially dependent free energy of formation. Ve find, that by removing the conventional assumptions, the presumed thermodynamic barrier to nucleation is absent. 

Single-Component System with Isotropic Interfaces and No Strain Energy. This relatively simple case could, for example, correspond to the nucleation of a pure solid in a liquid during solidification. For steady-state nucleation, Eq. 19.16 applies with AQC given by Eq. 19.4 and it is necessary only to develop an expression for /3C. In a condensed system, atoms generally must execute a thermally activated jump over a... 

If particles (or ions) are already present in a supersaturated vapor, nucleation will take place preferentially on these particles at supersaturations far smaller than for the homogeneous vapor. In this case, nucleation takes place heterogeneously on the existing nuclei at a rate dependent on the free energy of a condensate cap forming on or around the nucleus. Heterogeneous nuclei always occur in the earth s atmosphere. They are crucial to the formation of water clouds and to the formation of ice particles in supercooled clouds. 

Pulsed laser deposition (PLD) [1-3] uses high-power laser pulses with an energy density of more than 108 W cm 2 to melt, evaporate, excite, and ionize material from a single target. This laser ablation produces a transient, highly luminous plasma plume that expands rapidly away from the target surface. The ablated material is collected on an appropriately placed substrate surface upon which it condenses and a thin film nucleates and grows. 

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