Laserspectroscopic investigations of the lithium-D-lines in magnetic fields

Laser-atomic-beam investigations of the lithiumD ₁- andD ₂-line in magnetic fields were performed using cw-laser excitation and fluorescence detection. For both isotopes⁶Li and⁷Li, the hyperfine splittings of the ground level 2² S _1/2 and the upper level of theD ₁-line, 2² P _1/2, as well as the isotopic shifts of theD ₁- and theD ₂-line were determined from the registrations without field. In magnetic fields, Zeeman- and Paschen-Back-effects of the lines were studied. Using the Zeeman pattern of theD ₁-line for a calibration of the field strength, values for the hyperfine constantsA andB of the 2² P _3/2-level of⁷Li could be derived from the Zeeman pattern of theD ₂-line.     

Hyperfine structure of Mn II by fast ion beam-laser spectroscopy

We report the first measurements of the hyperfine splitting of the fine structure levels 3d ⁵'4s a ⁵ S ₂ and 3d ⁵ 4p z ⁵ P _1,2,3 ⁰ in singly ionised manganese in a collinear fast ion beam-laser experiment. The ions are excited by the intracavity frequency doubled output of a ring dye laser. The observed linewidth is sufficiently narrow to identify all hyperfine components of each fine structure level.     

Investigations of radiative lifetimes in the 3p5p configuration of neutral silicon

Lifetimes for the³ S ₁,³ P _{0, 1, 2} and³ D _{1, 2, 3} states in the 3s ²3p5p configuration of silicon have been determined using stepwise dye laser excitation and time resolved detection. A comparison is made with theoretical values, calculated using multi-configuration Hartree-Fock wavefunctions. Laser-evaporation was used to produce free silicon atoms by focusing a Nd: YAG laser on a rotating silicon target.     

Isotope shifts and hyperfine structures investigation of doubly excited levels in SrI

We measured isotope shifts and hyperfine structure of visible transitions of stable strontium isotopes by means of Doppler-free saturated absorption spectroscopy. In particular, we investigated transitions between excited states where the upper level involves two excited electrons. We report hyperfine coupling constants for the levels 5p4d¹D₂, 5p4d³F₂, 5s4d³D₁, 5s6s³S₁, 5s5p³P₁ and, for some of the studied transitions, we separate the specific mass and volume contribution to the isotope shifts.     

J and term dependences in the isotope shift of Eu I

High-resolution laser atomic beam spectroscopy has been applied to studyJ and term dependences in the isotope shift of the levels 4f ⁷5d6s a ¹⁰ D _J ,a ⁸ D _J of Eu I. A parametric analysis of the isotope shift has been performed. TheJ dependence is interpreted through two term-dependent parametersz _5d , and the term dependence through one parameterΔT:z _5d (a ¹⁰ D)=44.1 (2.6) MHz,z _5d (a ⁸ D)=55.9 (2.3) MHz,ΔT=408.5 (3.2) MHz. Ab initio Hartree-Fock and Dirac-Fock calculations have been made to interpret these parameters. Within the accuracy of the calculations the parameters can be attributed to field shift effects.     

Hyperfine structure measurements of the metastable (3d 6 4s 2)3 H 4, 5, 6 states of57Fe: Configuration interaction in the hyperfine structure of the iron atom

We report the hyperfine structure (hfs) measurement of the metastable (3d ⁶ 4s ²)a ³ H _{4, 5, 6} states of⁵⁷Fe. The kHz-precision of these experimental results together with the hyperfine structure values of (3d ⁶ 4s ²)a ⁵ D _{1, 2, 3, 4}, (3d ⁷ 4s)a ⁵ F _{2, 3, 4, 5}, and (3d ⁷ 4s)a ³ F _{2, 3, 4}, which were measured earlier, allowed to determine a very detailed set of effective radial parameters describing the hfs of these states, using a new parametrization method. This method treats one- and two-body contributions to the hfs separately. In this way configuration interaction effects in the hfs of the⁵⁷Fe atom can be studied in detail and compared with configuration interaction effects in the fine structure of the same atom.     

Hyperfine structure of the 4f 7 (8 S 0) 6s 7 S 3 0 level in151,153Eu II by fast ion beam — laser spectroscopy

The hyperfine structure (hfs) of the level 4f ⁷(⁸ S ⁰) 6s ⁷ S ₃ ⁰ in^151,153Eu II has been measured with collinear fast ion beam — laser spectroscopy. The hfs of the⁷ S ₃ ⁰ level has been measured with interferometric methods previously but, to our knowledge, this is the first measurement with the laser ion beam technique. In the present experiment the hfs of the 4f ⁷(⁸ S ₇ ^2/0 ) 6p _1/2 levels were also obtained. Corresponding magnetic dipole and electric quadrupole coupling constantsA andB are evaluated.     

An improved laser vaporization cluster source and time-of-flight mass spectrometer

The radiative lifetimes of the 7p ² P _{3/2, 1/2} states of silver and the hyperfine structure of the 7p ² P _3/2 state have been measured using pulsed laser excitation and direct observation of the induced fluorescence light decay. In order to excite this doublet, VUV radiation at 185 nm was applied, as generated by frequency tripling and anti-Stokes Raman shifting of the output of a Nd: YAG laser pumped dye laser. The lifetimes were found to be τ=255(20) ns and τ=285(25) ns for theJ=3/2 state andJ=1/2 state, respectively. The hyperfine structure of the 7p ² P _3/2 state was measured by the quantum beat method. The magnetic dipole interaction constant for the¹⁰⁷Ag isotope was found to bea=?4.5(2) MHZ.     

Hyperfine structure in 5s 4d 3 D —5snf transitions of87Sr

The hyperfine spectra of the 5s4d ³ D ₁-5s20f, 5s4d ³ D ₂-5s23f, and 5s 4d ³ D ₃-5s32f transitions of⁸⁷Sr (I=9/2) have been measured by collinear fast beam laser spectroscopy. The structure in the upper configurations is highly perturbed by fine structure splitting that is of comparable size to the hyperfine interaction energy. These perturbations can be adequately treated with conventional matrix diagonalization methods, using the 5s-electron magnetic dipole interaction terma _5s and the unperturbed fine structure splittings as input parameters. Additionally, hyperfine constants for the lower 5s4d ³ D configurations, including theA- andB-factors and a separation of the individuals- andd-electron contributions to these factors, are derived.     

Hyperfine structure investigations of the tantalumI blend λ=6356.14 Å

The TaI line 6356.14 Å, up to now classified as the transition 5d ³6s ² a ⁴ P _5/2?5d ³6s(a ⁵ F)6p z ⁴ F ₇ ^2/0 , is a blend with a second transition, which is related to the additional levels 5d ⁴(b ³ G)6s a ⁴ G _9/2?39641.24 cm^?1 J=7/2°. Using laser excitation with optogalvanic and laser-induced fluorescence detection, the hyperfine constants of the four levels involved and the distance of the center wavelengths of the two fine structure transitions could be determined.     

The effect of hyperfine structure on the collisional relaxation of the thallium atom excited by laser beam

We present a theoretical analysis of the transient population inversions which appear in the optically pumped thallium (6² P _1/2, 6² P _3/2, 7² S _1/2) atom. We account for the hyperfine structure and we assume that the pumping occurs in the presence of buffer gas. Numerically computed time dependencies of population differences between the Zeeman sublevels of hyperfine levels of the 7² S _1/2 and 6² P _{1/2, 3/2} states are given. It is demonstrated how the described effects depend on the strength of the atom-field coupling and buffer gas pressure. The role of resonant and nonresonant pumping is explained.     

Magnetic field-induced ΔF=±2,3,4 transitions in the Eu I-spectrum

The occurrence of ΔF=±2, ±3, and ±4 transitions in the hyperfine structure of the Eu I lineλ 629.1 nm (4f ⁷6s ² a ⁸ S _7/2?4f ⁷6s6p z ⁸ P _5/2) was investigated with the application of high-resolution laser-atomic-beam spectroscopy. It was possible to show that the appearance of such transitions depends on the magnitude of an external magnetic field. Calculations of the hyperfine Zeeman splittings of the excited and the ground state were performed. This allowed the identification of the forbidden transitions.     

Hyperfine structures and level isotope shifts of then 2 S 1/2 (n=7 – 12)- andn 2 D 3/2,5/2 (n=6 – 10)-levels of203,205Tl measured by atomic beam spectroscopy

Applying atomic beam laser spectroscopy, hyperfine constants as well as level isotope shifts of the (6s ² ns)² S _1/2 levels (n = 7 – 12) and (6s ² nd)² D _3/2,5/2 levels (n = 6 – 10) have been measured in²⁰³Tl and²⁰⁵Tl. Furthermore, some new hyperfine constants and level isotope shifts of the Tl² P _1/2,3/2-states are presented together with corrected results of earlier experiments. The hyperfine splittings have been compared with the predictions of the semiempirical theory. For theD-states a relatively poor agreement between these theoretical predictions and experimental results has been found. Using the experimental level isotope shifts and the δ〈r ²〉 value from muonic X-ray data, results of single-configuration Dirac-Fock calculations have been tested.     

Natural radiative lifetimes in the2 S 1/2 and2 D 3/2, 5/2 sequences of neutral copper

Natural radiative lifetimes have been measured of the 3d ¹⁰ ns ² S _1/2 (n=6?10) and of the 3d ¹⁰ nd ² D _{3/2, 5/2} (n=5?9) sequences by using two step excitation of copper atoms in an atomic beam. The states investigated were populated by the light from two pulsed dye lasers pumped by the same Nd:YAG laser. The lifetimes of the² D sequence increase regularly with increasing principal quantum number. This is not the case for the² S series, because of configuration interaction in the² P series. In addition the lifetime of the 3d ¹⁰5p ² P _3/2 state has been measured together with its branching ratio.     

Lifetime measurements of highly excited Rydberg states of strontium I

Lifetimes of Rydberg states of the triplet-series 5s ns ³ S ₁ withn = 19–23, 35 and 5s nd ³ D ₃ withn = 18–20, 23–28 in the spectrum of neutral strontium have been determined. Observation of the exponential decay after excitation by a pulsed laser in a fast atomic beam and subsequent state-selective field ionization was employed. The lifetimes of the states of the³ S ₁-series show the expectedn*³ dependence on the effective principal quantum number, while the³ D ₃-series is disturbed by configuration mixing. Furthermore, state re-populations induced by black-body radiation have been observed.     

Collision energy dependence of He and Ne capture by C 60 +

The hyperfine structure and the isotope shifts in the optical transition of HfI with λ=5903 Å have been investigated using high resolution laser spectroscopy. The magnetic dipole and electric quadrupole hyperfine splitting constants of the lower 5d ² 6s ² a ³ F ₃ and upper 5d ² 6s 6p z ⁵ G ₃ ⁰ levels have been determined for the two stable odd hafnium isotopes¹⁷⁷Hf and¹⁷⁹Hf.     

Laser and radiofrequency spectroscopy of the 5d 4 6s 6 D multiplet in Ta I

The hyperfine structure (hfs) of¹⁸¹Ta has been investigated using laser radio-frequency double resonance and high resolution laser spectroscopy on collimated atomic beams. The magnetic dipole and electric quadrupole hyperfine structure coupling constants of the 5d ^{4 6} s 6D _{3/2, 5/2, 7/2, 9/2} metastable states have been determined using radio-frequency spectroscopy. In the 5d ⁴ 6s ⁶ D _1/2 metastable state and the excited 5d ³ 6s 6p ⁴ D _3/2,⁶ D _{5/2, 9/2} as well as the unidentified 28 182.6 cm^–1 and 30 021.2 cm^–1 states, hfs constants have been obtained from high resolution laser spectroscopy. A radio-frequency converter has been developed in order to reach the frequency region 2.7–10 GHz.     

Hyperfine structure investigations in excitedD-states of171Yb and173Yb

The hyperfine structure splittings in the excited 4f ¹⁴6s6d states of¹⁷¹Yb and¹⁷³Yb have been measured. Isotope selection was achieved by stepwise laser excitation of the¹ D ₂ and³ D _{2, 1} states. The³ D ₃ state of¹⁷¹Yb was excited via collisional excitation of an intermediate level. The magnetic and electric hfs coupling constants are given and compared to ab initio values calculated from relativistic self-consistent-field wavefunctions.     

On the hyperfine structure and isotope shift of radium

The hyperfine structure and isotope shift of the heaviest known alkaline earth element radium (Z=88) have been studied in both the atomic Ra I and ionic Ra II spectra. The measurements, carried out by on-line collinear fast-beam laser spectroscopy, yield the hyperfine constantsA andB of the 7s and 7p _1/2 states in Ra II, of all states of the excited 7s 7p configuration and the 7s 7d ³ D ₃ state in Ra I. The data allow a consistent evaluation of the nuclear moments for eight odd-A radium isotopes. In particular, a complete analysis of the hyperfine structure of thesp configuration in the two-electron system provides a stringent test of the validity of the semi-empirical modified Breit-Wills theory. It is shown that the effective operator formalism is equivalent, if relativistic correction functions are used to reduce the number of parameters. The semi-empirical hyperfine fields are evaluated and found to agree generally with those from ab-initio calculations. The isotope shifts in thes?p,s ²?sp,sp?sd transitions are analysed semi-empirically and compared with ab-initio calculations. The consistency of the different analyses proves their validity and classifies the spectrum of Ra I as a model case for a simple and clean two-electron spectrum.