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High-resolution laser spectroscopy has been performed for the rare-earth elements as well as Ba by using a tunable diode laser together with a well collimated atomic beam. Hyperfine structures and isotope shifts have been measured for eight transitions in Ba I, Ce I, Sm I, Eu I, Gd I and Yb I. Hyperfine constants A and B have been determined for the 4 f 7 5 d 6 s 6 p 11 F 5 level of 155,157 Gd, and the 4 f 14 6 s 6 p 3 P 2 , 4 f 14 6 s 7 s 3 S 1 levels of 171,173 Yb. The field shifts and 6 s -electron densities at the nucleus have been derived for the studied elements and compared with the Hartree–Fock calculation.

High-resolution atomic-beam laser spectroscopy in Eu I has been performed using a tunable diode laser. The hyperfine structure (hfs) and isotope shift of the 4 f 7 6 s 2 8 S 7/2 –4 f 7 6 s 6 p 10 P 9/2 transition at 686.45 nm have been measured. The hfs constants A and B of 151 Eu and 153 Eu have been determined for the upper state 4 f 7 6 s 6 p 10 P 9/2 , and the hyperfine anomaly has been derived. The Δ F =+2 transitions, normally forbidden, have been induced by applying a magnetic field of approximately 1 G. Their intensity dependences on the magnetic field strength and on the hfs splittings agreed with the first-order perturbation theory, which considers the mixing between the closely lying hfs levels in the ground state.

High-resolution diode-laser spectroscopy has been performed on atomic beams of natural Gd and Dy. Isotope shifts of the even-mass isotopes have been measured for two transitions in Gd I and one transition in Dy I. Specific mass shifts, as well as field shifts, have been derived for transitions of 4 f 7 5 d 6 s 2 –4 f 7 6 s 2 6 p in Gd I, and 4 f 10 6 s 2 –4 f 9 5 d 6 s 2 in Dy I; the specific mass shift is much larger than the normal mass shift. It has been found that the specific mass shift of the 4 f 10 6 s 2 –4 f 9 5 d 6 s 2 transition in Dy I is about one order of magnitude larger than that of the 4 f 7 5 d 6 s 2 –4 f 7 6 s 2 6 p transition in Gd I. This shows that the specific mass shift, related to the correlation effect between electrons, strongly depends on the orbital angular momentum of electrons.

High-resolution laser spectroscopy in Sm I has been performed by using a tunable diode laser together with a highly collimated atomic beam. Hyperfine structures and isotope shifts of Sm isotopes have been measured for four transitions in the wavelength region of 636–687 nm; the largest isotope shift has been observed. Hyperfine constants A and B of 147 Sm and 149 Sm have been determined for six levels. By using the purest s 2 - s p transition with the largest isotope shift, nuclear parameters λ, changes in mean-square nuclear charge radii δ , and nuclear deformation parameters δ have been derived and discussed.

High-resolution atomic-beam ultraviolet (UV) laser spectroscopy in Dy I and Er I has been performed. Isotope shifts have been measured for two transitions in Dy I and one transition in Er I. Specific mass shifts and field shifts have been derived for the studied transitions, and large differences between the two 4 𝑓 1 0 6 𝑠 2 – 4 𝑓 1 0 6 𝑠 6 𝑝 transitions in Dy I have been found. From the derived specific mass shifts and field shifts, configuration mixing at the upper levels of transitions has been discussed.

A high‐resolution laser spectroscopy system for refractory elements with an argon‐ion‐ sputtering atomic beam source was constructed, and it has been demonstrated that the sputtering method is extremely useful as an atomic beam source for high‐resolution laser spectroscopy to measure hyperfine structures and isotope shifts for refractory elements, such as Hf, Ta, and W. This source produced intense neutral atomic beams of more than 1010 atoms/s for these elements, and the yield was easily controlled by adjusting the argon‐ion current and the acceleration voltage. Resonance linewidths were 32, 66, and 48 MHz for Hf, Ta, and W, respectively, which are sufficient to measure the hyperfine structures and the isotope shifts in optical transitions. With this system, the signal‐to‐noise ratio reached more than 106. In addition, the temperature of the sputtered atoms found was rather low compared to the kinetic energy given to the atoms.

High-resolution atomic-beam ultraviolet (UV) laser spectroscopy in Gd I has been performed. Isotope shifts have been measured for five UV transitions and hyperfine structure constants of 155 Gd and...

High-resolution atomic-beam ultraviolet (UV) laser spectroscopy in Ti I has been performed. Isotope shifts have been measured for seven UV transitions and hyperfine structure constants of 47 Ti and 49 Ti have been determined for five high-lying levels. Large specific mass shifts and significant field shifts have been derived for the studied transitions; the specific mass shift of the 3 d 2 4 s 2 –3 d 3 4 p transition is quite larger than that of the 3 d 2 4 s 2 –3 d 2 4 s 4 p transition. J dependences of isotope shift have been obtained for the 3 d 2 4 s 4 p 3 F term and are mainly contributed from the specific mass shift.

High-resolution atomic-beam laser spectroscopy in Gd I and Er I has been performed in the ultraviolet (UV) region. Isotope shifts have been measured for three UV transitions in Gd I and two transitions in Er I. Hyperfine structure constants of 155,157 Gd and 167 Er have been newly determined for two high-lying levels. Specific mass shifts and field shifts have been derived for the 4 f 7 5 d 6 s 2 –4 f 7 5 d 2 6 p and 4 f 7 5 d 6 s 2 –4 f 8 5 d 6 s transitions in Gd I as well as the 4 f 12 6 s 2 –4 f 11 5 d 6 s 2 and 4 f 12 6 s 2 –4 f 11 5 d 2 6 s transitions in Er I. Results show that the specific mass shift strongly depends on the orbital angular momentum of electrons.

Combined with a collimated atomic beam source, diode laser without external cavity has been used as a spectroscopic light source to study atomic hyperfine structures and isotope shifts of Ba i. Spectroscopic measurements of the 6s 2 1 S 0 – 6s6p 3 P 1 transition of Ba i have been carried out. All hyperfine peaks of 135,137Ba have been clearly seen and resolution of 50 MHz has been attained. Hyperfine constants A and B of the 3 P 1 state of 135,137Ba have been determined. Isotope shifts of stable Ba isotopes have also been measured. From the measured isotope shifts, the 6s electron density at the nucleus has been deduced to be 76.4(53) a.u. and discussed in terms of the Hartree-Fock approximation.