The measurements of the hyperfine structure of free, naturally occurring, alkali atoms are reviewed. The experimental methods are discussed, as are the relationships between hyperfine structure data and other atomic constants.

Experimental determinations of the hyperfine structure in the alkali atoms

This compilation extends the 1991 listing of atomic data by Morton to the heavier stable elements from germanium to bismuth Technetium, thorium, and uranium are added because they can live long enough to be astrophysically detectable The tabulation emphasizes resonance lines, ie, lines the lower level of which is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 91175 A This paper has attempted to review all data published by mid-1999 and includes some later material     The tables contain the best data available to the author on level designations, ionization potentials, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often-used combinations of log gf and log λf All ion stages with classified lines are included Individual components resulting from isotope shift and hyperfine structure are listed explicitly for Rb I, Cs I, Hg I and Hg II, Ti II, and Pb II The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed     This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels The data also are relevant to the study of stellar atmospheres, particularly those with enhanced abundances of heavy elements

https://iopscience.iop.org/article/10.1086/317349/pdf

Atomic Data for Resonance Absorption Lines. II. Wavelengths Longward of the Lyman Limit for Heavy Elements

The field of the direct measurement of atomic and molecular lifetimes has been characterized in the past few years by the development of several new and powerful techniques and by an improving ability to control and limit the measurement inaccuracies of older techniques. The establishment of a wide range of accurate values for atomic and molecular lifetimes is now possible. This review deals with the measurement of lifetimes of atoms and molecules in the gas phase, in the range 10-10-10-5 s, and concentrates on the more accurate and promising techniques, which are grouped together according to whether their most prominent feature is the means of excitation or the interference between excited levels or the coincident detection of two decay events. Possible sources of systematic error are discussed at length and the theoretical background appropriate to the measurements is given when necessary. The techniques and their areas of applicability are compared and the likely future development of them is discussed.

https://iopscience.iop.org/article/10.1088/0034-4885/40/1/001/pdf

The measurement of lifetimes in atoms, molecules and ions

Nuclear Data Sheets for A = 137☆

Fonctions d'onde atomiques relativistes dans l'approximation du champ central: Application AU CS I

The level crossing method has been used for the investigation of the hyperfine structure of the 6p2P3/2 and 7p2P3/2 levels of the isotopes Cs133, Cs135, and Cs137. For the hyperfine coupling constants a and b and for the lifetimes Τ we find: a(6p Cs133)=50.72(3) gJ/−1.345, b(6p Cs133)=−0.38(18) gJ/−1.345 a(7p Cs133)=16.610(6) gJ/−1.3349, b(7p Cs133)=−0.15(3) gJ/−1.3349 a(6p Cs135)=53.64(4) gJ/−1.345, b(6p Cs135)=7.41(32) gJ/−1.345 a(7p Cs135)=17.570(6) gJ/−1.3349, b(7p Cs135)=2.35(7) gJ/−1.3349 a(6p Cs137)=55.80(4) gJ/−1.345, b(6p Cs137)=7.54(20) gJ/−1.345 a(7p Cs137)=18.274(6) gJ/−1.3349, b(7p Cs137)=2.37(4) gJ/−1.3349 (MHz), Τ(6p2P3/2)=29.7(2) −1.345/gJ ns, Τ(7p2P3/2)=135(1) −1.3349Jns. From a comparison with double resonance results the gJ factor of the 7p2P3/2 level was deduced: gJ(7p2P3/2=−1.3349(10). Level crossing measurements in the 8p2P3/2 state of Cs133 give for the gJ factor and the lifetime the following results: gJ(8p2P3/2)=−1.3353(14), Τ(8p2P3/2)=310(15) ns. Using recently calculated relativistic correction factors and applying corrections for core polarization and the Sternheimer effect, we obtain for the quadrupole moments: Q(Cs133)=−0.0030 b, Q(Cs135)=+0.052 b, Q(Cs137)=+0.052 b.

Level crossing investigation of the 6p^(2)P_(3/2) and 7p^(2)P_(3/2) levels of Cs 133, Cs 135, and Cs 137

Our previous level crossing measurements in the 6, 7, and 8 p 2 P 3/2 levels of Cs 133 have been extended to the 9 and 10 p 2 P 3/2 levels. For the magnetic dipole and the electric quadrupole interaction constants a and b we obtain ##IMG## [http://ej.iop.org/images/1402-4896/5/4-5/010/img1.gif] {figure 1} The natural lifetime of 9 p 2 P 3/2 was found to be 390 (30) ns. The previous analysis for the 6 and 7 p 2 P 3/2 levels is revised, taking new experimental data from this and other laboratories into account. This leads to a better consistency for the quadrupole moments Q for Cs 135 and Cs 137 as evaluated from the 6 and 7 p 2 P 3/2 levels. We obtain Q (Cs 135 ) = +0.052 (4) barn Q (Cs 137 ) = +0.053 (4) barn

Investigation of the np ^(2)P_(3/2) Level Sequence in the Cs I Spectrum by Level Crossing Spectroscopy

Natural lifetimes of some highly excited levels in the Pb-I spectrum have been measured by the zero field level crossing (Hanle) method. The levels were reached by optical excitation from the metastable 6p
2 3
P
2 and 6p
2 3
P
1 states, were a considerable population had been created by means of adc discharge in a Pb atomic beam. An atomic beam source producing atoms in metastable states is described. For the lifetimes τ of the investigated levels we find:τ(6p(1/2)6d
3
D
1)=3.74(28) ns,τ(6p(1/2)6d
3
F
2)=25.8(1.3) ns,τ(6p(1/2)6d
3
D
2)=4.17(−31)
(−49) ns,τ(6p(1/2)6d
3
F
3)=6.08(26) ns,τ(6p(3/2)7s)3
P
2=5.85(27) ns. These results are compared with lifetimes derived from oscillator strengths given in the literature.

Lifetimes of some highly excited levels in the Pb-I spectrum measured by the Hanle method

High-resolution laser spectroscopy using a pulsed dye-laser acting on a collimated atomic beam has been used to determine the isotope shifts in the 3 988 A YbI line. The following results have been obtained:Δσ(176, 174)=−509(4)MHz,Δσ (174, 173)=−291(10) MHz,Δσ(174, 172)=−530(4) MHz,Δσ(172, 171)=−414(5) MHz andΔσ(172, 170)= −665(10) MHz. The sign of the magnetic dipole interaction constant in the1
P
1 state for171Yb is found to be negative,a(1
P
1, 171)=−213.4(3.0) MHz. The electric quadrupole interaction constant for173Yb in the1
P
1 state is found to beb(1
P
1, 173)=605(20) MHz.

Analysis of the isotope shifts and hyperfine structure in the 3 988 Å (6 s 6 p 1 P 1 ↔6 s 2 1 S 0 ) YbI line

As a first application of optical double resonance and zero field level crossing spectroscopy to the elements of the sixth group in the periodic table of the atoms, the 5p36s5S2 level in the Te-I spectrum was investigated using natural tellurium in a high temperature quartz cell. For the electronic Lande-factor and the natural radiative lifetime the following values were obtained:

$$g_J \left( {5p^3 6s^5 S_2 } \right) = - 1.9657\left( {12} \right),\tau \left( {5p^3 6s^5 S_2 } \right) = 71.8\left( {2.2} \right)ns.$$

S Rydberg

Papers

Level crossing investigation of the 6p^(2)P_(3/2) and 7p^(2)P_(3/2) levels of Cs 133, Cs 135, and Cs 137

Investigation of the np ^(2)P_(3/2) Level Sequence in the Cs I Spectrum by Level Crossing Spectroscopy

Lifetimes of some highly excited levels in the Pb-I spectrum measured by the Hanle method

Analysis of the isotope shifts and hyperfine structure in the 3 988 Å (6 s 6 p 1 P 1 ↔6 s 2 1 S 0 ) YbI line

Optical double resonance and zero field level crossing spectroscopy applied to the 5p^(3)6s^(5)S_(2) level in the Te-I spectrum