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Re: [ccp4bb] Wavelength of Copper Kalpha
 

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CCP4bb <-- 2007 <-- October 2007 <-- 10 October 2007
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Subject: Re: Wavelength of Copper Kalpha
From: "Bryan W {- dot -} Lepore" bryanlepore {- at -} MAIL {- dot -} UTEXAS {- dot -} EDU
Date: 2007-10-10 		Next message:
Subject: easy way to make alternate conformers?
From: John Bruning jbruning {- at -} SCRIPPS {- dot -} EDU
Date: 2007-10-10


Subject: Re: Wavelength of Copper Kalpha
From: "Santarsiero, Bernard D {- dot -} " bds {- at -} UIC {- dot -} EDU
Date: 2007-10-10
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

CCP4bb navigation

CCP4bb <-- 2007 <-- October 2007 <-- 10 October 2007
Previous message:
Subject: Re: Wavelength of Copper Kalpha
From: "Bryan W {- dot -} Lepore" bryanlepore {- at -} MAIL {- dot -} UTEXAS {- dot -} EDU
Date: 2007-10-10 		Next message:
Subject: easy way to make alternate conformers?
From: John Bruning jbruning {- at -} SCRIPPS {- dot -} EDU
Date: 2007-10-10


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