Text: PHOTOELECTRIC EFFECT, ABSORPTION IN METALS For example, cobalt foil absorbs both of the CuK emission lines, as does nickel, but nickel dramatically discriminates between the and radiation: although both and are absorbed by nickel, the is much more strongly absorbed by nickel than is the , so that the relative proportions of the two components of the beam shifts in favor of the . This technique is frequently used to "filter out" lines, in order to obtain a beam of more nearly monochromatic radiation. Table I: Emission and Absorption Wavelengths (These values were copied from the TELTRON manual; they originated in the International Tables for X-Ray Crystallography) Observe the discrepancy between atomic number order and atomic weight order for Cobalt and Nickel. Element Wavelengths (nm) Emission Absorption Atomic Number Atomic Mass Symbol Kx Kb Mean K edge 23 50.94 V 0.255 0.228 0.242 0.227 24 52.00 Cr 0.229 0.208 0.2l8 0.207 25 54.94 Mn 0.2l0 0.191 0.200 0.189 26 55.85 Fe 0.194 0.176 0.185 0.174 27 58.93 Co 0.179 0.162 0.170 0.161 28 58.71 Ni 0.166 0.149 0.157 0.148 29 63.54 Cu 0.154 0.139 0.146 0.138 30 65.37 Zn 0.144 0.129 0.137 0.128

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