An example of K-alpha lines are those seen for iron as iron atoms radiating X-rays spiralling into a black hole at the center of a galaxy. For such purposes, the frequency of the line is adequately calculated to 2-digit accuracy by the use of Moseley's law. This formula is 10.2 eV multiplied by the square of a quantity one less than the atomic number of the element in question (atomic number minus 1). For example, K-alpha for iron (Z = 26) is calculated in this fashion as 10.2 eV (25)2 = 6.38 keV. For astrophysical purposes, Doppler and other effects (such as gravitational broadening) show the iron line to no better accuracy than 6.4 keV. |
Post a Comment for " "