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Specialty Chemistry Forums => Materials and Nanochemistry forum => Topic started by: 408 on November 03, 2010, 03:50:09 AM

Title: Surface atom percentage calculation
Post by: 408 on November 03, 2010, 03:50:09 AM

Hi,

Is there a simple formula for calculating the percentage of surface atoms on a nanoparticle?  I am curious about something, and math is not my strongpoint.

Thanks,
408

Title: Re: Surface atom percentage calculation
Post by: Borek on November 03, 2010, 07:47:36 AM

I would try simple geometry. Assume nanoparticle is spherical, assume some size for atoms, calculate atom cross section from the diameter, divide sphere surface by atom cross section and you have number of atoms on the surface - you are off (+) by at most 20-30%. Even better result you will get assuming some lattice and calculating not cross section, but surface per atom.

Title: Re: Surface atom percentage calculation
Post by: Stepan on November 05, 2010, 04:47:18 PM

In heterogeneous catalysis they use terminology "metal dispersion" (D) which is ratio of the atoms on the surface of the crystal to total number of atoms. It was very popular topic in late 80-th early 90th.  Generally D=K/d where d - diameter of the particle, and K - is coefficient which depends on shape of the crystal and it crystalline structure. Formula does not work for "clusters" where number of atoms is too low (1-30)