1. The total attenuation coefficient, μ0 with units of cm2g−1, is defined by the equationI =I
o
e
−μ0
x whereI
o
is the incident beam intensity,I is the transmitted beam intensity, andx is the sample thickness in g/cm2.
2. J. H. Hubbel, Natn. Bur. Stand. Rep. NSRDS-NBS 29 (1969).
3. C. M. Davisson andR. D. Evans. Rev. modern Physics24, 101 (1952).
4. 28.5 keV for125I is an average energy which takes into account the relative intensities of the different lines.
5. G. White Grodstein, Natn. Bur. Stand. Circular 583 (1957).