X-Ray Fluorescence Yields of Al, Cl, Ar, Sc, Ti, V, Mn, Fe, Co, Y, and Ag

The K-fluorescence yields of elements in the range 13≤Z≤27 and the L-fluorescence yields of yttrium and silver have been measured. A monochromatic x-ray beam obtained through the Ross filter difference method produced the fluorescence in foil targets and argon gas, and some of the fluorescent x rays were detected by a flow counter mounted at right angles to the primary x rays. The incident x-ray flux was determined by a measurement in the same geometry of the x-ray flux scattered by helium. The fluorescence yields and standard deviations are ωK(Al)=0.0379±0.0023, ωK(Cl)=0.0970±0.0054, ωK(Ar)=0.119±0.007, ωK(Sc)=0.190±0.010, ωK(Ti)=0.221±0.012, ωK(V)=0.250±0.012, ωK(Mn)=0.303±0.017, ωK(Fe)=0.347±0.022, ωK(Co)=0.366±0.020, ωL(Y)=0.0315±0.0028, and ωL(Ag)=0.0659±0.0037. The uncertainties include a 5% uncertainty in the helium-scattering cross section assumed for the data reduction. These K-fluorescence yields and the values for fluorescence yields for Z≥30 considered best by Fink, Jopson, Mark, and Swift are fitted with the semiempirical formula [ωK(1-ωK)]ⁿ=A+BZ+CZ³, using n=1/4 and 1/3. The best fit is given by [ωK(1-ωK)]1/3=-0.1019+0.03377Z+1.178×10^-6Z³, with a standard deviation of 2.4%.