http://phys.org/news/2012-12-hot-electrons-impossible-catalytic-chemistry.html
Hot electrons do the impossible in catalytic chemistry The incoming laser light optically excites surface plasmons<http://phys.org/tags/surface+plasmons/>on the metal surface <http://phys.org/tags/metal+surface/>, and the plasmons then decay into hot electrons <http://phys.org/tags/hot+electrons/>. Because of their high energies, the hot electrons extend further away from the nanoparticles than electrons with lower energies do. If another atom or molecule that can accept the electron is nearby, the hot electron can transfer into that acceptor's electronic states. In these experiments, the researchers adsorbed H2 molecules on the gold nanoparticle surface, a procedure that is commonly performed in heterogeneous catalysis <http://phys.org/tags/heterogeneous+catalysis/>, in which the adsorbed molecules act as reactants <http://phys.org/tags/reactants/>. The researchers found, as the main result of their study, that some of the hot electrons could transfer into the closed shells of the H2 molecules and cause the two hydrogen atoms <http://phys.org/tags/hydrogen+atoms/> to separate, or dissociate. This process, called "plasmon-induced dissociation of H2 on Au," could improve the efficiency of certain chemical reactions<http://phys.org/tags/chemical+reactions/> . As a byproduct of the polariton lifecycle, an irregular metal surface will produce high energy electrons through this nanoplasmonic mechanism. Read more at: http://phys.org/news/2012-12-hot-electrons-impossible-catalytic-chemistry.html#jCp On Wed, Oct 16, 2013 at 11:41 PM, Kevin O'Malley <[email protected]>wrote: > I suspect this is the key. 42% better absorption into the metal matrix. > If it's a surface effect, then why would higher absorption into the bulk > create more reliable excess heat events & reactions? > > > On Wed, Oct 16, 2013 at 8:37 PM, Kevin O'Malley <[email protected]>wrote: > >> http://scitation.aip.org/content/aip/journal/jcp/101/12/10.1063/1.467850 >> >> Direct reaction of gas‐phase atomic hydrogen with chemisorbed hydrogen on >> Ru(001) >> >> T. A. >> Jachimowski<http://scitation.aip.org/content/contributor/AU0666706;jsessionid=35ucjlhs7rg8q.x-aip-live-03> >> 1 and W. H. >> Weinberg<http://scitation.aip.org/content/contributor/AU0332482;jsessionid=35ucjlhs7rg8q.x-aip-live-03> >> 1 >> [image: +] View Affiliations >> J. Chem. Phys. 101, 10997 (1994); http://dx.doi.org/10.1063/1.467850 >> >> >> The adsorption of gas‐phase atomic hydrogen on the Ru(001) surface >> results in a saturation coverage of 1.42 hydrogen adatoms per primitive >> surface unit cell, which may be compared with a saturation coverage of one >> hydrogen adatom per primitive surface unit cell in the case of dissociative >> chemisorption of molecular hydrogen. The observed saturation fractional >> coverage of 1.42 results from a steady‐state balance of adsorption of >> gas‐phase atomic hydrogen and reaction of gas‐phase hydrogen with >> chemisorbed hydrogen adatoms, which produces molecular hydrogen that >> desorbs from the surface at a temperature at least 150 K below the >> temperature of recombinative desorption of two hydrogen adatoms. The cross >> section of this direct reaction of hydrogen was found to be remarkably >> large, approximately 40% of the cross section for chemisorption of the >> gas‐phase atomic hydrogen. The reaction was found not to depend on surface >> temperature nor was there an observable kinetic isotope effect. >> © 1994 American Institute of Physics >> > >
