We apply our technique of using a Rb-stabilized ring-cavity resonator to measure the frequencies of various spectral components in the 555.8-nm 1 S 0 → 3 P 1 line of Yb. We determine the isotope shifts with 60 kHz precision, which is an order-of-magnitude improvement over the best previous measurement on this line. There are two overlapping transitions, 171 Yb͑1 / 2 → 3 / 2͒ and 173 Yb͑5 / 2 → 3 / 2͒, which we resolve by applying a magnetic field. We thus obtain the hyperfine constants in the 3 P 1 state of the odd isotopes with a significantly improved precision. Knowledge of isotope shifts and hyperfine structure should prove useful for high-precision calculations in Yb necessary to interpret ongoing experiments testing parity and time-reversal symmetry violation in the laws of physics.

Optical selectivities of calcium isotopes have been calculated for the 4s 2 1 S 0 422.7 nmdouble-resonance ionization scheme using the spectral simulation (SS) approach. Optical selectivities obtained by the SS approach are in good agreement with the results obtained by the density matrix formalism. Studies on the effect of laser detuning and linewidth on optical selectivities indicate that lasers with 50 MHz linewidth for both the excitation steps can yield an optical selectivity of 2.2 × 10 5 , which is adequate for selective excitation of the 41 Ca isotope for certain applications.

Numerical computations of ionization efficiency and isotope selectivity of 176 L u have been carried out for the following three-step ladder type photoionization scheme, 5 d 6 s 2 2 D 3 / 2 ( 0.0 c m − 1 ) − − − ⟶ 540.4068 n m ⁡ 5 d 6 s 6 p 4 F 5 / 2 o ( 18504.58 c m − 1 ) − − − ⟶ 535.0626 n m 5 d 6 s 7 s 4 D 3 / 2 ( 37193.98 c m − 1 ) − − − ⟶ 618.0061 n m 53375 c m − 1 A u t o i o n i z a t i o n S t a t e → L u + , by invoking the density matrix formalism for the laser–atom interactions. Equations of motion have been derived for the odd isotopes by inclusion of hyperfine levels. The line shapes and their effect on the ionization efficiency and isotope selectivity have been discussed in detail. The effects of power of excitation and ionization lasers, spectral bandwidths, pulse delays, Doppler broadening of the atomic ensemble on the ionization efficiency, and degree of enrichment have been presented. Optimum conditions for the power of excitation, detunings, and other system parameters for the selective yet efficient photoionization of 176 L u have been identified.

We report the absolute frequency of the important 5S(1/2)-->7S(1/2) two-photon transition in (87)Rb. We access the upper state using two dipole-allowed transitions via the intermediate 5P(3/2) state. This allows us to use much lower laser intensities compared to directly driving the two-photon transition, thereby avoiding potential errors due to the AC Stark shift. Collisional shifts are also minimized because the atomic density required is several orders of magnitude smaller. Our values are consistent with earlier frequency-comb measurements.

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The efficiency of the two photoionization schemes scheme 1: 4f 14 6s 2 1 S 0 (0 cm −1 ) 555.648 nm −→ 4f 14 6s6p 3 P o 1 (17 992.007 cm −1 ) 581.027 nm −→ 4f 13 6s 2 6p( 7 2 , 3 2 ) 2 (35 196.98 cm −1 ) 582.79 nm −→ autoionization state (52 353 cm −1 ) → Yb + and scheme 2: 4f 14 6s 2 1 S 0 (0 cm −1 ) 398.8 nm −→ 4f 14 6s6p 1 P o 1 (25 068.222 cm −1 ) <394 nm−→ Yb + has been studied by a spectral simulation approach for the isotope-selective excitation of the 168 Yb isotope. Isotopic selectivities have been computed for 4f 14 6s 2 1 S 0 -4f 14 6s6p 3 P o 1 (555.648 nm), 3 P o 1 -( 7 2 , 3 2 ) 2 (581.027 nm) and 4f 14 6s 2 1 S 0 -4f 14 6s6p 1 P o 1 (398.8 nm) transitions for various laser bandwidths of the excitation lasers. The degree of enrichment of the lowabundant 168 Yb isotope has been computed using the obtained isotopic selectivity values. Results obtained for scheme 1 are in good agreement with the results reported earlier. The abundance of 168 Yb isotope has been computed for various laser linewidths of the excitation laser and Doppler widths for scheme 2. Comparison of the two photoionization schemes for isotope-selective photoionization of the 168 Yb isotope has been made. The present computational method has been examined for computation of degree of enrichment for the photoionization schemes under consideration.