The width of the line cannot be zero; it will depend on temperature,
external fields, the isotope abundances of the atoms in the ammonia, etc.
Note that the precisely given frequency for cesium in SI units in the
BIPM brochure comes with similar caveats:
"The second, symbol s, is the SI unit of time. It is defined by taking
the fixed numerical
value of the caesium frequency, ∆νCs, the unperturbed ground-state
hyperfine
transition frequency of the caesium 133 atom, to be 9 192 631 770 when
expressed in
the unit Hz, which is equal to s^−1."
"The reference to an unperturbed atom is intended to make it clear that
the definition of the
SI second is based on an isolated caesium atom that is unperturbed by
any external field,
such as ambient black-body radiation."
Real quantum mechanical systems, of course, operate at non-negligible
temperature and in the presence of external fields.
Perry
On 9/20/21 13:19, paul swed wrote:
According to one of the articles 23,870,129.007 Hz +/- 10 Hz. That may have
been the measurement limit at the time and the technology.
Paul
On Mon, Sep 20, 2021 at 1:15 PM Andy Talbot <[email protected]> wrote:
What's the exact resonance frequency of ammonia? To as many sig figures
as it's been calculated.
Googling just seems to throw up "approximately 23.8GHz"
_______________________________________________
time-nuts mailing list -- [email protected] -- To unsubscribe send an
email to [email protected]
To unsubscribe, go to and follow the instructions there.
