In reply to Eric Walker's message of Sat, 27 Jul 2013 08:22:30 -0700: Hi, [snip] >My two questions for Robin (or anyone else): > > - Do you have a sense of how tunneling would be affected at the > locations that hydrodgen/deuterium pairs are likely to be if a significant > population of nickel electrons were excited into Rydberg states? I think > we can assume Ron's mechanism is also at play, but perhaps not. (If we get > set aside Ron's mechanism, we have gammas to deal with.)
If a significant number were in Rydberg states, I think it could make quite a large difference. As long as at least 1 electron is between two Hydrogen nuclei, they will be attracted to one another (actually to the electron), so the local electron density makes a very large difference to the tunneling probability (same thing as Coulomb barrier penetration[1]). However, if you take into consideration that some percentage of the Pd atoms will have already lost at least one valence electron anyway (gone wandering off through the lattice), then I'm not sure how easy to would be to get at least one of the remaining electrons into Rydberg orbitals. Nevertheless, the concept is very interesting, and does appear to tie together a number of "loose ends". If combined with Horace's theory, perhaps as the introductory step to his process, it may also explain the Ni results, though I don't think it would explain why 61Ni is unreactive. BTW the tetrahedral sites are probably much better suited if you want to go down this road. Temperature would play an important role in this model, not just in creating Rydberg states, but also because thermal vibration about an equilibrium point can bring two nuclei closer together, thus reducing the distance that needs to be bridged by tunneling. This could be the link to the Debye temperature. [1] Tunneling probability is affected by both the height and width of the barrier. The barrier height represents the classical energy required to overcome it, so this is directly related to the charges on the respective nuclei. The mass of the nuclei also play a role in determining the height. The barrier width is essentially the separation distance between the two nuclei at the instant of tunneling. BTW2 I suspect that electrons entering Rydberg states would cause the lattice to swell. So it might be worth looking at the temperature dependence of the thermal expansion coefficient, and see if there is knee in the curve at some point. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
