- Atomic percent
Atomic percent or at.% is a measure of
concentration ofdopant , used inchemistry , physics ofsolid state laser s andspectroscopy .The meaning of this term strongly depends on the context, host material and dopant. In particular, atomic percent may refer to:(A) Molar fraction [http://en.wikipedia.org/w/index.php?title=Concentration#Table_of_concentration_measures] [http://www.semicontimes.com/common/glossary.asp?termid=61] ,which is ratio m~ frac{number~of~atoms~of~dopant}{number~of~ atoms~ of~ solution}
(B) The molar (or atomic) percentage [http://www.rp-photonics.com/doping_concentration.html] refers to the ratio
m frac{number~ of~ atoms~ of~ dopant}{number~of~ atoms~ of~ solution,~ which~ can~ be~ substituted~ with~ the~ dopant}~.For example, according to the definition (B), 100% doped m Yb: Y_3!~Al_5!~O_{12} is justm Yb_3!~Al_5!~O_{12}, not pure
Yb , as it would be in the case of definition (A).Definition (B) is widely used inlaser physics , and theambiguity of the term"atomic percent" may cause confusions.Atomic percent is also used in applications involving atomic isotopes, such as nuclear engineering. In this context, the atomic percent refers to the ratio of the number of atoms of a particular isotope to the total number of atoms in the sample.
Wikimedia Foundation. 2010.