[Ifeffit] EXAFS mean free path in small particlesMatthew, This is one of the references stating that surface plazmon intensity vanishes as the particle size gets smaller than 2nm: C.N.R.Rao et al, Size-Dependent Chemistry: Properties of Nanocrystals, Chem. Eur. J. 2002, 8, No. 1, p. 29. Here is the quote: "Gold nanocrystals of varying diameters between 2 and 4nm exhibit distinct bands around ~ 525 nm, the intensity of which increases with size (ref, ref). The intensity of this feature becomes rather small in the case of 1 nm diameter particles basically due to a reduced number of "itinerant" electrons in the electron cloud." There are other evidences that small particles have DOS similar to molecules, not typical metals. Most notable is the evidence that HOMO-LUMO band grows to more than 1 eV at sizes of 1 nm range. The point is, to my opinion, that since In the most interesting range, below 2nm, the plasmon activity decreases, therefore its effect on EXAFS interpretation, if any, should be negligible. Regards, Anatoly -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov]On Behalf Of matthew marcus Sent: Tuesday, June 14, 2005 11:09 AM To: ifeffit@millenia.cars.aps.anl.gov Subject: [Ifeffit] EXAFS mean free path in small particles I'm working on a couple of projects involving nanoparticles, and a collaborator pointed out an old paper by Zhao and Montano (PRB 40,3401(1989)) which claimed theoretical reasons why the electron mean free path in nanos should be smaller than in bulk. This would cause coordination numbers to be underestimated. The effect is supposedly due to a surface plasmon which grows in importance as particle size shrinks. I have reasons why I think this paper exaggerates the possible effects, but I'm posting this to see what other people think about this effect. The paper seems to have gone down into obscurity, but that doesn't mean it isn't right. Thanks. Matthew Marcus _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit