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The BIPM restated this definition in its 26th conference (2018), "The second is defined by taking the fixed numerical value of the caesium frequency ∆Cs, 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." [4]
The second, symbol s, is defined by taking the fixed numerical value of the caesium frequency, Δν Cs, the unperturbed ground-state hyperfine transition frequency of the caesium-133 atom, [9] to be 9 192 631 770 Hz, which is equal to s −1.
The BIPM restated its definition at its 26th conference in 2018: "[The second] is defined by taking the fixed numerical value of the caesium frequency Δν Cs, 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." [86]
The exact modern SI definition is "[The second] is defined by taking the fixed numerical value of the cesium frequency, Δν Cs, the unperturbed ground-state hyperfine transition frequency of the cesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s −1." [1]
The output frequency of the VCXO (typically 5 MHz) is multiplied by a frequency synthesizer to obtain microwaves at the frequency of the caesium atomic hyperfine transition (about 9 192.6317 MHz). The output of the frequency synthesizer is amplified and applied to a chamber containing caesium gas which absorbs the microwaves.
A main goal of precision spectroscopy of a two-level atom is to measure the absorption frequency between the ground state |↓ and excited state |↑ of the atom. One way to accomplish this measurement is to apply an external oscillating electromagnetic field at frequency and then find the difference (also known as the detuning) between and (=) by measuring the probability to transfer |↓ to ...
ion gyrofrequency, the angular frequency of the circular motion of an ion in the plane perpendicular to the magnetic field: = electron plasma frequency , the frequency with which electrons oscillate ( plasma oscillation ): ω p e = ( 4 π n e e 2 m e ) 1 2 ≈ 5.64 × 10 4 n e 1 2 rad/s {\displaystyle \omega _{pe}=\left({\frac {4\pi n_{e}e^{2 ...
For each atom, the column marked 1 is the first ionization energy to ionize the neutral atom, the column marked 2 is the second ionization energy to remove a second electron from the +1 ion, the column marked 3 is the third ionization energy to remove a third electron from the +2 ion, and so on.