Hyperfine structure and isotope shift studies of rhenium by laser optogalvanic spectroscopy

Doppler-limited high resolution laser optogalvanic spectra of six transitions of rhenium lying in the range 560–620 nm have been recorded. Isotope shifts between the two natural isotopes of rhenium,¹⁸⁵Re and¹⁸⁷Re, have been calculated in all the six transitions. Hyperfine coupling constants for eight levels belonging to the configurations 5d ⁵6s ², 5d ⁶6s, 5d ⁴6s ²6p and 5d ⁵6s6p are reported. Wherever possible our constants are compared with those given by others.     

Hyperfine structure and isotope shift of highly excited barium-I states

High-resolution laser-spectroscopy measurements of hyperfine structure and isotope shifts were performed for the 6snd ¹ D ₂ sequence of Ba-I in the regionn=12–24. Stepwise laser excitations of a collimated atomic beam were used. A strong influence on the hyperfine structure is observed at the perturbation atn=14, caused by interaction with the 5d7d configuration. Whereas the isotope shift for the even isotopes stays essentially constant with increasingn, the odd isotopes exhibit a strong change, indicating hyperfine-induced shifts.     

Hyperfine structure measurements in metastable states of165Ho

The hyperfine structure constants and the electronic g _J factor of the state 4f ¹¹ 6s ^{2 4} I _11/2 belonging to the holmium ground multiplet have been measured using the atomic beam magnetic resonance technique combined with a state-selective laser-induced detection of the resonant atoms. By the same method the g _J factor of the level 4f ¹¹6s ²⁴ I _9/2 was determined, while the hyperfine structures of this metastable state and of two high-lying even parity states have been investigated by high resolution laser spectroscopy. The results for the experimentalA andB factors of all four members of the ground multiplet allow a least-squares evaluation of the three magnetic dipole and the three electric quadrupole effective radial parameters for the configuration 4f ¹¹ 6s ² of holmium, yielding an accurate value for the spectroscopic nuclear electric quadrupole moment:Q _hfs(¹⁶⁵Ho)=2.716(9)b (uncorrected for quadrupole shielding). From a comparison to the quadrupole moments measured in mesic holmium atoms the shielding factor could be estimated.     

Hyperfine structure and isotope shift study in singly ionized lead

Hyperfine structure and isotope shifts in five optical transitions: 424.5 nm ( – ), 537.2 nm ( – ), 554.5 nm ( – ), 560.9 nm ( – ) and 666.0 nm ( – ) of Pb  II have been measured. As a light source the discharge tube was used. The hyperfine structure measurements were performed using metallic isotope ²⁰⁷Pb. For isotope shifts measurements natural lead was used. The high resolution spectral apparatus consisted of a silver coated Fabry-Perot etalon and a grating spectrograph combined with a CCD camera used as a detector. In the analysis of the spectra a computer simulation technique was used. The hyperfine structure observations yielded the splitting constants A for seven levels of Pb II. The isotope shift studies enabled to separate the mass and the field shifts and to determine values of changes of the mean square nuclear charge radii.     

Hyperfine structure of metastable states of barium studied by atomic-beam magnetic-resonance with laser detection

An atomic-beam magnetic-resonance technique together with laser detection has been used to study the hyperfine structure of the metastable states of the 6s5d configuration of barium. Preliminary results for the ³D₁ state, which has not been studied previously, are given.     

Hyperfine structure and lifetimes of metastable states studied by means of laser excitation of stored ions

Studies of hyperfine structure of metastable states are facilitated by storage rings and ion traps. Here we report on the development of a method to study metastable states of stored singly charged ions by laser excitation. The experiments were performed at the accelerator and storage ring CRYRING at the Manne Siegbahn Laboratory in Stockholm. We discuss means to improve the resolution and the possibility to extend the method to highly charged ions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Hyperfine splitting,isotope shift,and level energy of the 3S states of (6,7)Li

We study the 2S-3S transition of (6,7)Li by high-precision laser spectroscopy using two-photon Doppler-free excitation and photoionization detection. Interferometric cross referencing to metrologic Rb 3S-5D two-photon transitions allowed measurement of the transition isotope shift and hyperfine splitting in the 3S state with precision at the 30 kHz level. The results are IS=11 453.734(30) MHz, A(3S)(6Li)=35.263(15) MHz, and A(3S)(7Li)=93.106(11) MHz. Combined with recent theoretical work, the isotope shift yields a new value for the change in squared nuclear charge radii DeltaR(2)=0.47(5) fm(2). This is compared with other work and some existing discrepancies are resolved.     

Hyperfine structure and isotope shift of the neutron-rich barium isotopes139–146Ba and148Ba

The hyperfme structure and isotope shift in the 6s ² S _1/2?6p ²P_3/2 line of Ba II (455.4 nm) have been measured by collinear fast-beam laser spectroscopy for the neutron-rich isotopes^139–146Ba and¹⁴⁸Ba. Nuclear moments and mean square charge radii of these isotopes have been recalculated. The isotope shift of the isotope¹⁴⁸Ba (T_1/2=0.64 s) could be studied for the first time, yieldingδ〈r²〉^138,148=1.245(3) fm².     

Applications of the two-photon doppler-free method: Hyperfine interactions and isotope shift measurements

The hyperfine structures are generally of the same order of magnitude as the Doppler broadening of optical transitions and so are the isotopic shifts in the case of heavy elements. When these structures are too small, one must use Doppler-free methods. Among these methods, the two-photon spectroscopy has obtained good results in highly excited levels. In our laboratory in Paris, we did measurements on neon and helium by two-photon excitation from metastable levels. The precision of the measurements is of the order of one MHz, which permits a precise comparison with theory. We compare the measurements on neon with the theory by Liberman and we obtain a good fit in the first approximation, but must introduce mixing of wave functions for an exact explanation. In the case of helium, we obtain a good fit with the theoretical values obtained from the wave functions by Accad, Pekeris and Schiff. We also give an example where another technique by polarization measurements permits us to obtain experimentally a hyperfine structuresmaller than the natural width. We also present a short review of the measurements done by the two-photon method in other laboratories on other elements, Pb, Tl, In and alkaline earths Ca, Sr. Ba.     

Hyperfine structure and isotope shifts of neutron-rich138–146Cs

The 6s²S_1/2-7_p ²P_3/2 transition in^138–142Cs (λ=455.5 nm) has been investigated by high-resolution collinear laser spectroscopy in a fast atomic beam. The isotopes are obtained by on-line mass separation of fission products. Nuclear moments and changes of mean-square charge radii are derived from hyperfine structure and isotope shift.     

Hyperfine structure and isotope shifts in near-infrared transitions of atomic nitrogen

We have obtained Doppler-free spectra of transitions in the → 2p²(³P) and → multiplets of atomic nitrogen using saturated absorption spectroscopy. These multiplets consist of respectively of seven and eight transitions, and have center of gravity wavelengths of 821 nm and 869 nm. Values for the hyperfine structure coupling constants of all the upper and lower states for these multiplets were obtained for both ¹⁴N and ¹⁵N. Isotope shifts of three transitions in each multiplet were also measured, and a significant J-dependence to the shifts was observed.     

Hyperfine structure and isotope shift measurements on 235U and laser separation of uranium isotopes by two-step photoionization

Two-step photoionization of an atomic beam and quadrupole mass analysis have been used for the precise measurement of the isotope shift between uranium isotopes 235 and 238 and the hyperfine structure of ²³⁵U. For the 5915 Å ground-state transition 15 hfs components were found. The residual atomic beam was isotopically enriched by factors 2.5 and 10 for ²³⁵U and ²³⁸U, respectively.     

Hyperfine structure measurements in metastable atomic states — nuclear spins of 201Pb and 203Pb

A new atomic-beam source has been used to populate metasbable states within the atomic ground-state configuration for lead. With this source and the atomic-beam magnetic resonance method, hyperfine structure measurements have been performed in metastable states to determine the nuclear ground-state spins of two lead isotopes as ${}^{203}\text{Pb}\text{(I =}\text{5}\text{2}\text{)}$, ${}^{201}\text{Pb}\text{(I =}\text{5}\text{2}\text{)}$.     

Topics in atomic hyperfine structure and isotope shift

Recent developments in atomic hyperfine structure and isotope shift are discussed under the following aspects: (i) Precise evaluation of nuclear moments and isotopic change of nuclear charge radii by quantitative computation of atomic structure or by calibration of the atomic constants through results from electronic and mesic X-ray spectroscopy. (ii) How to apply spectroscopic methods to nuclei far off stability. (iii) What can be learned from a systematic investigation of long isotopic chains.     

Hyperfine splitting and isotope shift in the optical transition of Eu isotopes and electromagnetic moments of Eu

The laser-induced resonance fluorescence in an atomic beam was used in order to measure the hyperfine splitting of the 4f ⁷ 6s ² and 4f^{7 6s6p} levels in ^151,153,155Eu isotopes. The hfs constants A and B of the unstable ¹⁵⁵Eu were determined for the first time: MHz, MHz and MHz. With these data and after corrections for second-order hyperfine structure perturbations the nuclear moments of ¹⁵⁵Eu were deduced: n.m. and b. In addition new and more precise values of the hfs constants of the excited state for the stable ^151,153Eu were obtained. They are as follows: MHz, MHz and MHz, MHz. The hyperfine anomalies % and % were extracted from the corrected hfs constants. Received 28 July 1999 and Received in final form 14 January 2000     

钐原子高激发态能级位置和同位素位移测量

本文首次用共振增强消多普勒双光子光谱技术对钐原子四个高激发态偶宇称能级进行了实验研究,得到了这些能级的位置和相应跃迁的同位素位移数据.     

Doppler-free two-photon laser spectroscopy of barium I: Hyperfine splitting and isotope shift of high lying levels

The Doppler-free two-photon absorption method performed with a narrowbandc w dye laser permitted high resolution measurements of transitions from the Ba I ground state 6s ^{2 1} S ₀ to several highly excited states. The lifetimes and hyperfine splittings of these states as well as the isotope shifts of the transitions have been determined accurately. The lifetime values are in agreement with transition probability data; the hyperfine splitting results show considerable configuration interaction effects. A detailed discussion of the isotope shifts is given.     

Electronic excitation of Ar atoms to metastable states and from metastable to higher states

The formation of the metastable states 3p ⁵4s of the Ar atom by an electron impact and the electronic excitation from these states to the higher levels 3p ⁵4p ArI are investigated in detail. The electronic excitation cross sections are determined based on a previously proposed approach to generalization of experimental and theoretical results. The method proposed consists in interpolation over the entire set of cross sections for each of the investigated levels of the Ar atom (measured by us previously or taken from the literature) using the four-parameter approximation of the dependences of the cross sections on the energy of incident electrons.     

Isotope shift measurement of high-lying atomic levels by multi-step photoionization

A new technique has been developed to measure isotope shifts of high-lying atomic levels using multi-step photoionization. This technique has been demonstrated with the measurement of isotope shift between²³⁵U and²³⁸U isotopes in the energy level at 34372.992 cm⁻¹. The value of isotope shift thus measured matches well with the value reported in literature.