On Wed, October 10, 2007 11:50 am, Bryan W. Lepore wrote:
> On Wed, 10 Oct 2007, Jim Pflugrath wrote:
>> It has come to my attention that the wavelength of a Copper Kalpha may
>> have changed over the years. At least this appears to be true if you
>> look at the International Tables.
>
> the 'natural' isotopic distribution must have changed, as it has with the
> biggest example lithium, since the 'nuclear age' - i take that to be the
> principal reason.
>
> and i take it that everyday-use copper anodes are isotopically impure?
>
> -bryan
>
The change was probably around 1967, when the meter was defined, slightly,
using krypton. Tungsten was used as a reference, and the kX to A ratio was
changed: Bearden, Rev Mod Phys, 39, 78 (1967).
old values from IT, volume III
alpha-1 1.54051
alpha-2 1.54433
beta-1 1.39217
beta-2 1.38102
alpha 1.54178
the ratio of I(alpha-2)/I(alpha-1) = 0.497
the units are kX/1.00202, and good to 1 in 25,000, based on kX, for 1962
(IT, 1962).
newer values, from IT, volume IV
alpha-1 1.540562
alpha-2 1.544390
beta-1 1.392218
beta-5 1.38109
based on the W K-alpha-1 line/peak at 0.2090100 A
Bernie Santarsiero
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