On 10/29/2011 09:12 PM, Poul-Henning Kamp wrote:
In message<[email protected]>, Attila Kinali writes:
Is it because they can be aproximated as single electron
systems due to the one electron in the valence orbit?
Yes. Basically that electron is in a "figure of eight" orbital
which means that it passes straight through, or possibly just
very close by, the proton, allowing their spin moments to interact.
Related to this is the question why only H, Rb and Cs are used.
Although, from my point of view there isnt anything that speaks
against using Li, K or Na, these are not used at all. At least i
couldnt find any papers or other documents describing frequency
standards build on these elements.
I belive K has been tried.
I belive the preference for H, Rb& Cs is that getting them as
single atoms doesn't require high temperatures.
Sodium lamps is common, so it's not a big issue. Buth large cavities to
support sub 1 GHz frequencies is unpractical, but possible.
The high temperature is however an issue for stability once you look
close enough.
Cheers,
Magnus
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