Level Isotope Shifts Research Articles

Level isotope shifts of indium 113 and 115

The isotope shifts of several Doppler-free two-photon lines of the series 5p 2P 1 2 , 3 2 - np 2P 1 2 , 3 2 ( n=16–43) and 5p 2P 1 2 - nf 2F 5 2 ( n= 8–14) in 113, 115 In have been measured with a thermionic heat-pipe diode modified for investigations of low pressure and strongly alloying elements. From the experimental data the residual level isotope shift (RLIS) of the 5p 2P 1 2 and 5p 2P 3 2 ground states have been extracted which show a very slight J-dependence. Taking into accou nt these data the RLIS of the 6 and 7s 2S 1 2 levels could be found from transition isotope shift data of other groups.

Estimation of the specific mass effect in the isotope shifts of energy levels in the optical spectrum of Ba I and Ba II

A graphical method for separating mass and volume effects from purely optical isotope shift data is presented and compared with King's “bunching” method. Recent experimental data on isotope shifts for a wide range of spectral lines in the naturally abundant isotopes of Ba I and Ba II are analysed. Some agreement is found with muonicx-ray data concerning the nuclear size for the isotopes 136, 137 and 138, but there is disagreement (over 20%) for the other isotopes. Thelevel isotope shifts are further parameterised in terms of a linear model, and the specific mass effect is decomposed into sums of one-electron and two-electron shift parameters with respect to the inert-gas like ground state of Ba III.

Experimental and theoretical investigation of the isotope shift of the 4D level in atomic potassium

Doppler-free two-photon laser spectroscopic measurements in the deep red spectral region have been performed on the transition 42 S 1/2→42 D J in the naturally abundant isotopes 39 and 41 of atomic potassium. The 4D level isotope shift, −81±12 MHz was obtained by combining the current results with data from Rydberg-state spectroscopy. Many-body perturbation theoretical calculations of the specific mass shift in the measured state are also presented. With the use of Brueckner orbitals the value −70 MHz was obtained in substantial agreement with the experimental result.

Isotope shifts in transitions between low-lying levels of Sr I by laser-atomic-beam spectroscopy

High-resolution laser-atomic-beam spectroscopy has been used to determine isotope shifts in five transitions between low-lying states of Sr I. With these results and existing data a parametric analysis of level isotope shifts has been performed. The transition isotope shifts have been separated into field shift and mass shift contributions with a King-plot procedure using model-independent nuclear charge equivalent radiiR k from muonic x-ray measurements. Values for the mean-square nuclear charge radiiδ〈r 2 〉 have been calculated from the field shifts in the optical transitions 5s 2 1 S 0-5s5p 3 P 1 and 5s5p 3 P 0-5s6s 3 S 1 and compared with correspondingδ〈r 2 〉 values evaluated from muonic x-ray data.

High-resolution studies of the Stark effect in even-purity Rydberg states of Ca I

High-resolution laser-atomic-beam spectroscopy has been applied to the study of the quadratic Stark effect in calcium 4sns3S states with principal quantum number n ranging from 14 to 45 and 4snd3D states with n=10 to 30. For the3D states the electric-field-induced splittings are comparable with the fine-structure splittings. The analysis takes account of both field-induced fine-structure mixing and zero-field deviations from LS coupling. The resulting polarisabilities are compared with calculations based on the Coulomb approximation. Satisfactory agreement is obtained. Accurate values of the fine-structure intervals in the 4snd3D series (n=14 to 30) and of the44Ca-40Ca isotope shift in a number of transitions from the 4s4p3P2state to 4sns3S1and 4snd3D3states have also been determined. From the latter data the residual level isotope shift in the 4s4p3P2state is derived. Fine-structure and Stark effect data for the 4snd levels near n=15, where the singlet and triplet series cross, indicate a stronger singlet-triplet mixing than previously assumed. This is explained in terms of small admixtures of doubly excited configurations in the 4snd levels resulting in a strong off-diagonal spin-orbit interaction.

Isotope shifts of energy levels in the naturally abundant isotopes of strontium and calcium

The isotope shifts of long series of spectral lines in the optical spectra of the alkaline-earth elements Ca and Sr have been measured by Doppler-free, two-photon laser spectroscopy with a thermionic diode. The variation of transition isotope shifts with transition energy yields the level isotope shifts with reference to the ionization limit and how these shifts vary with the binding energy of the optically active electron. The largest isotope shifts of levels in these elements appear to arise from the specific-mass effect in the presence of state mixing.

Precision isotope shifts for the heavy elements II Neutral thorium

High-resolution spectra of a 232ThI4/230ThI4 electrodeless discharge lamp were obtained from 5600 to 36000 cm−1 with a Fourier-transform spectrometer. The splittings of more than 2800 Th i isotopic doublets were measured to an accuracy of 0.001 cm−1. Level isotope shifts were determined for 274 even and 318 odd levels of Th i.

Doppler-free optogalvanic spectroscopy of 88,86Sr I and II

We have measured the isotope shifts of some dipole transitions between excited states of the even strontium isotopes 88 and 86 by applying the technique of Doppler-free intermodulated optogalvanic spectroscopy to a heat-pipe discharge. We were also able to investigate the isotope shift of the Sr II resonance line at 4216.6 Å optogalvanically in the mentioned pair of isotopes. Because the 5 snf 1 F 3 series appear to have zero level isotope shifts for n⩾6, we can give residual level isotope shifts (RLIS) of several odd-parity states of 88,86Sr I. The RLIS of the 5 snp 1P 1 series show pronounced configuration mixing around n = 7.

Isotope shifts of energy levels in40K and39K

The isotope shifts of several energy levels in the mildly radioactive isotope 40 of potassium with respect to the stable isotopes 39K and 41K have been measured by Doppler-free two-photon spectroscopy on transitions to highly excited Rydberg states of atomic potassium. The contribution of mass-dependent effects ('specific mass shift') to the isotope shifts of the measured levels is assessed. Volume effects are found in the isotope shift of the ground state.

Level isotope shifts of6,7Li

The isotope shift of the Doppler-free two-photon lines 2S-4S and 2S-3,4D in 6,7Li have been measured with a thermionic diode. Because the 2S-3D and 2S-4D lines show, within the experimental uncertainty, the same residual transition isotope shift (transition isotope shift minus Bohr mass shift) the method recently proposed by Niemax and Pendrill (1980) could be applied to find the residual level isotope shifts of the ground state (2S) and the 4S level from the measured transition shifts. Taking into account all available experimental isotope line shift data of other authors the level shifts of some other lower levels in 6,7Li are also given. The experimental values are in satisfactory agreement with specific mass shift data found by Martensson (1981) in ab initio Hartree-Fock calculations up to the second order.

Electronic configurations and isotope shifts of the energy levels of the neutral dysprosium atom

Electronic configurations of the energy levels of the neutral dysprosium atom have been suggested on the basis of isotope shift studies carried out in the first spectrum of dysprosium using highly enriched isotopes excited in liquid-air-cooled hollow cathode lamps and a photoelectric recording Fabry-Perot spectrometer. Isotope shift Δ T(164-160) have been evaluated for 85 even and 82 odd energy levels. The configurations 4f 9d6s6p, 4f 96p6s 2 and 4f 106s6d along with two new configurations 4f 95d 26p and 4f 106p 2 have been assigned to even levels whereas the configurations 4f 95d 26s, 4f 106s6p and 4f 105d6p have been assigned to some odd energy levels of the neutral dysprosium atom.

The isotope shift of the a 10D-term of the configuration 4 f75 d6 sinEuI

With interferometric optical hyperfine-structure techniques the isotope shifts of the five odd Eu I levels 4f 75d6s a 10D 5 2 , 7 2 , 9 2 , 11 2 , 13 2 were measured (relative to the ground state 4f 76s 28S 7 2 to be -144.72(1 0) mK, -143.5(6) mK, - 142.5(6) mK, -141.4(7) mK , respectively. The fact that the isotope shifts of these 4f 75d6s levels are nearly equal (about∓2 mK near - 143 mK) is a proof of the high purity of this configuration. The small J-dependence is shown to be due to a crossed-second-order-effect and described by the IS-parameter z 5 d = -2.48(20) mK. Because of the purity accurate screening ratios are evaluated, in good agreement with relativistic Hartree-Fock calculations of Coulthard. For the three levels 4f 75d6p z 10F 13 2 , 15 2 and z 8D 5 2 IS-values were measured to be -256.2(7) mK, -259(2) mK and -256(2) mK . On account of their purity a new and more accurate figure for the relative isotope shift of the configuration 4 f 75 d6 p, i. e. -258(2) mK, can be derived.

Isotope shifts of individual nS and nD levels of atomic potassium

Isotope shifts of individual nS and nD levels of atomic potassium

Isotope shifts of individual nS and nD levels of atomic potassium

A new method is reported which enables isotope shifts of single atomic levels to be directly extracted from measurements of isotope shifts of transitions between two levels. The method, which is based on the assumption that the isotope shift of a sufficiently high Rydberg level is given solely by the simple Bohr (or normal) mass shift, is demonstrated in an experiment in which isotope shifts of Doppler-free, two-photon transitions (4S-nS, 7<or=n<or=18; 4S-nD, 5<or=n<or=17) in atomic potassium are measured. Appreciable residual isotope shifts are found between 39K and 41K for energy levels lying more than 1000 cm-1 below the atomic ionisation limit.

Precision isotope shifts for the heavy elements I Neutral uranium in the visible and near infrared

A Fourier transform spectrometer was used to obtain high-resolution spectra of a 234UI4/238UI4 electrodeless discharge lamp. Over 2000 uranium isotope shifts were measured in the visible and near-infrared regions. Level isotope shifts were determined by least squares for 183 odd and 518 even levels of U i with an overall standard deviation of 0.0036 cm−1.

Force field of cyanogen from vibrational spectra of isotopic species

The Raman spectra of ( 12C 14N) 2, ( 13C 14N) 2, and ( 12C 15N) 2 in the vapor phase have been studied. From the isotope shifts of several levels the Fermi resonance constant, W 01000-0002 00 = 41 cm −1, has been determined. The observed data, together with earlier infrared data, allow a determination of all the first order anharmonic corrections and thus of the fundamental harmonic frequencies. From these results, force constants and compliance constants of a general quadratic force field are calculated and discussed.

Spectroscopic Measurement of the Nuclear Spin and Magnetic Moment of ^39Ar†

The nuclear spin and magnetic moment of argon 39 have been determined by high-resolution optical spectroscopy, using a pressure-swept Fabry–Perot interferometer, photoelectric detection, and digital data processing. The 39Ar was produced through the 39K(n,p)39Ar reaction by pile neutron irradiation of KF. The spectrum of 39Ar was excited in a miniature hollow cathode cooled by liquid nitrogen. Helium was used as a carrier gas. By application of the intensity rules, the nuclear spin was determined to be 72, in agreement with the shell model. Anomalous spin values which were measured from some lines were shown to be caused by self-absorption from excited states. Using the A value of −23.76 ± 0.04 mK (1 mK = 10−3 cm−1) measured for the 1s2 level and the previous result for 37Ar the nuclear magnetic moment has been determined to be −1.3 ± 0.3 nuclear magnetons. The measured B value for the 1s2 level is B = +2.80 ± 0.02 mK. Several level structures and isotope shifts are reported.