0000000000338092
AUTHOR
H-jürgen Kluge
New determination of the electron's mass.
A new independent value for the electron's mass in units of the atomic mass unit is presented, ${m}_{e}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.0005485799092(4)\mathrm{u}$. The value is obtained from our recent measurement of the $g$ factor of the electron in ${}^{12}{\mathrm{C}}^{5+}$ in combination with the most recent quantum electrodynamical (QED) predictions. In the QED corrections, terms of order ${\ensuremath{\alpha}}^{2}$ were included by a perturbation expansion in $Z\ensuremath{\alpha}$. Our total precision is three times better than that of the accepted value for the electron's mass.
Absolute frequency measurements on the 2S→3S transition of lithium-6,7
The frequencies of the 2S–3S two-photon transition for the stable lithium isotopes were measured by cavity-enhanced Doppler-free laser excitation that was controlled by a femtosecond frequency comb. The resulting values of 815 618 181.57(18) and 815 606 727.59(18) MHz, respectively, for 7Li and 6Li are in agreement with previous measurements but are more accurate by an order of magnitude. There is still a discrepancy of about 11.6 and 10.6 MHz from the latest theoretical values. This is comparable to the uncertainty in the theoretical calculations, while uncertainty in our experimental values is more than a hundred-fold smaller. More accurate theoretical calculation of the transition freque…