Electron bubble formation

Figure 12 Process of electron bubble formation in liquid neon, (a) Injection of quasifree electron (b) temporary localization at density fluctuation (c) stable electron bubble formed. (Redrawn from the data of Sakai, Y, Schmidt, W.F., and Khrapak, A.G., Chem. Phys., 164,139, 1992.)...

The total energy of the system of N He atoms and one electron, Et, may be decomposed into the sum of the electronic energy, Ee, and the energy required for bubble formation, Eb. 

The most prominent feature in luminescence of Xe, Kr and Ar - the so-called M-band (Fig.la) - is formed by 1,3SU+— Xg+ transitions in (R2 ) excimer M-STE (R=rare gas atom). The negative electron affinity (Table 1) is a moving force of the cavity ("bubble") formation around A-STE in the bulk of crystal, and the desorption of atoms and excimers from the surface of solid Ne and Ar [11], Radiative "hot" transitions in desorbed excimers of Ar and Ne result in a W-band. 4-bands are emitted by A-STE (R ). 

G. Superfluidity Effects on the Formation Dynamics and on Electron Tunneling of Electron Bubbles in ( He) Clusters... 

In Fig. 13 we also present the energetics of the ( He) cluster with a bubble at the equilibrium electron bubble radius, with inferred (Section III.C) from the electron bubble. These results manifest the marked increase of Ec/N upon bubble formation, which is due to cluster deformation. Data were obtained on the bubble radius Rb, the cluster deformation energy per atom Ea/N [Eq. (57)], the cluster mean density n, and the cluster radius R for ( He)jy clusters. These results reflect on the energetic implications (i.e., the increase of E /N) and on the structural manifestations (i.e., cluster expansion with increasing the bubble radius). 

Let us explain what happens with the formation of a bubble. When the electrocatalytic reaction occurs with the production of a gaseous product, it dissolves in the electrolyte until it reaches saturation. It is transported from the electronic conductor to the ionic conductor only by convective diffusion. When the solution concentration exceeds supersaturation, we are able to activate the nucleation sites to the bubble formation. This condition depends on the morphology of the surface and the kind of electrolyte and its viscosity. The growth of the bubble induces a microconvective flow on the electrolyte, pushing in various radial directions each bubble from an ideal center of the surface ( active site ). When each bubble attains a certain size, the buoyancy exceeds its adhesion and the bubble leaves the surface producing a drag flow. 

Helium bubble formation (HBF) uses electron microscopy to measure the distribution of bubble sizes that form when a solid inqtlanted with He ions is annealed [73Aitl]. For He in Nb, bubble formation occurs by migration and coalescence, not by He diffusion. Thus, the size distribution can be related to the surface diffusion coefficient, which governs bubble migratioa Spatial resolution is about 10 nm. 

Y denotes the surface tension of the liquid. Bubble formation is fostered in liquids with small surface tension and where the atoms or molecules repel the electron. 

Rosenblit, M. and Jortner, J., Dynamics of the formation of an electron bubble in liquid helium, Phys, Rev. Lett., 75, 4079,1996. 

A strained, solid-like, and well-ordered liquid skin serves as an elastic covering sheet for a liquid drop or a gas bubble formation the skin is covered with locked dipoles due to charge polarization by the densely trapped core electrons. Temperature dependence of surface tension reveals the atomic cohesive energy at the surface the temperature dependence of elastic trtodulus gives the mean atomic cohesive energy of the specimen. 

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