We demonstrate a simple technique to measure the resonant frequency of the 398.9-nm ${}^{1}{S}_{0}\ensuremath{\leftrightarrow}{}^{1}{P}_{1}$ transition for the different Yb isotopes. The technique, which works by observing and aligning fluorescence spots, has enabled us to measure transition frequencies and isotope shifts with an accuracy of 60 MHz. We provide wavelength measurements for the transition that differ from previously published work. Our technique also allows for the determination of Doppler-shifted transition frequencies for photoionization experiments when the atomic beam and the laser beam are not perpendicular and furthermore allows us to determine the average velocity of the atoms along the direction of the atomic beam.
The hyperfine transitions in the 399 nm ${^{1}S}_{0}\ensuremath{\leftrightarrow}{^{1}P}_{1}$ line in
173Yb overlap with the transition in
172Yb. We use transverse laser cooling on this line to selectively deflect
173Yb atoms from a thermal beam containing both isotopes. We then use an acousto-optic modulator to span the frequency difference between the hyperfine transitions, and hence measure hyperfine structure in the
1P1 state. Our precise values for the hyperfine constants, ${A}_{173}=57.693\ifmmode\pm\else\textpm\fi{}0.006\text{ }\text{MHz}$ and ${B}_{173}=609.028\ifmmode\pm\else\textpm\fi{}0.056\text{ }\text{MHz}$, improve previous values significantly.
Hyperfine splittings for the 39 K and 41 K isotopes and the isotope shift for the 4s 2 S 1/2 → 6s 2 S 1/2 two-photon transition have been measured using sub-Doppler fluorescence spectroscopy. We have accurately measured the transition isotope shift, and a discrepancy has been found in the earlier reported transition isotope shift value, which has been corrected. The resulting hyperfine splitting values of 418.2 (5) and 230.4 (1.3) MHz for the 39 K and 41 K isotopes respectively are in agreement with previous measurements. The precision of the absolute frequency values for the two-photon transition has been improved by about two orders. Our measured magnetic dipole constants for the upper 6 2 S 1/2 state for the 39 K and the 41 K isotopes are consistent with the earlier measured values.
Compared to other stable isotopes of
Yb+,
173Yb+ has a richer hyperfine structure, which leads to more favorable clock transitions, spectroscopic techniques for probing new physics, and more sophisticated quantum computing architectures. However, to date, its electronic spectrum remains poorly characterized. Here, we report on efficient laser cooling, state preparation, and detection of a single trapped
173Yb+ ion. The previously unobserved
2S1/2→2D3/2 electric quadrupole transition at 436 nm is coherently excited, and the isotope shift between
171Yb+ and
173Yb+ on this transition is determined with an uncertainty of 1.4 Hz. Using microwave spectroscopy, we resolve the hyperfine structure (HFS) of the
2D3/2 state with a relative uncertainty below
10−8. From the HFS measurement data, we infer for
173Yb a nuclear magnetic octupole moment
Ω=−0.062(8)(b×μN) with uncertainty reduced by more than 2 orders of magnitude compared to previous studies. The data also allow us to determine hyperfine anomalies for the
2S1/2 and
2D3/2 states.
The hyperfine splitting of the 6P1/2–6P3/2 fine structure transition in 207Pb+ ions at 710 nm has been measured by c.w. laser excitation and subsequent observation of the weak fluorescence radiation at the same wavelength. The ions were confined in an rf quadrupole trap and buffer gas cooled by collisions with He atoms at 10−5 mbar pressure. From the observed level splitting and the simultaneously recorded transmision of a Fabry-Perot etalon we determined the hyperfine splitting constants A(6P1/2) = 13·001(48) GHz and A(6P3/2) = 0·589(23) GHz. From a small impurity of 208Pb of our isotopically enriched sample we determined the isotope shift of the transitions to Δv(207–208) = 252(40) MHz.
Spectroscopy of the 411-nm transition in
171Yb+ has been performed and the feasibility of its use as an optical frequency standard has been demonstrated. The
2S1/2(F=0,mF=0)−−2D5/2(F=2,mF=0) frequency, at zero-magnetic field, has been measured to be 729 487 779 566(153) kHz. This transition is free from the first-order Zeeman shift and has a measured second-order shift of +0.38(8) Hz/(\ensuremath{\mu}
T)2. In addition, the hyperfine structure of the
2D5/2 level has been deduced by driving the other hyperfine components of the 411-nm transition, showing it to be inverted. The
2D5/2 hyperfine splitting, measured to be -191(2) MHz, implies an A factor of -63.6(7) MHz. These data taken in conjunction with previous work yield an isotope shift of ${\ensuremath{\nu}}_{171}\ensuremath{-}{\ensuremath{\nu}}_{172}=+1317.1(1.3)\mathrm{MHz}$ for this transition between the 171 and 172 isotopes.