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The Karlsruhe Light Ion Facility (“KALIF”) enables us to heat material by proton impact. For solid targets in the proton focus we reach a specific energy deposition between 1 and 10 MJ/g resulting in a hot and dense plasma. To study the plasma development we exploit the satellite structure of the K α soft X-rays emitted or absorbed by the plasma produced by subrange targets. The experimental results are compared with corresponding calculations. Time-integrated K α emission spectra have been observed for Al and Si. They show that the peak kT in the target plasma can be above 20 eV. The spectra also give some clue as to the beam intensity of each individual KALIF shot. For K α absorption spectroscopy a Nd : YAG laser system was installed. It is used to provide soft X-ray backlighter radiation from a laser induced plasma. Different elements were studied as laser targets to cover the K α absorption features of the elements around Al. We found the M transition group of the rare earth elements useful with respect to the wavelengths needed.

Isotope shifts and hyperfine splittings in optical transitions for atomic ions of the thorium isotopes227Th to230Th and232Th have been measured by laser spectroscopy on stored ions. From the isotope shift data, changes of the mean square charge radii are determined. A continuous increase of the charge radius with mass numberA is observed, in agreement with droplet model calculations. The results indicate that the odd-even staggering for Th is different from that one of the neighbouring isotones of Fr and Ra. There is some empirical evidence from systematics for an inversion of the staggering and the appearance of an octupole deformation atN ≦137. The hyperfine splitting for229Th for 3 electronic levels is given.

The isotope shifts and hyperfine splittings for 11 strontium isotopes (A=80–90) and two isomers for the optical transition λ=293.2 nm were measured. The magnetic dipole and electric quadrupole moments and the changes of the mean square charge radii are derived. The results are discussed with respect to the increasing nuclear deformation and the anomalous coupling scheme of light Sr nuclei.

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.

We have observed the optically forbidden 3s-4d transition in sodium vapor, using two-photon excitation with a cw dye laser and monitoring the 4d population via fluorescence cascades. High resolution spectra without Doppler broadening and line widths of less than 30 MHz were obtained with two counter-propagating laser beams, whose Doppler shifts cancel. We have measured the 4d fine structure splitting to be 1035 ± 10 MHz.

Precision tuning of a narrow-band cw dye laser allows to determine effects that normally are masked by the natural width of short-lived atomic states. With the 15 kHz accuracy of our laser system we were able to detect small frequency shifts between the components of the 3 s → 4 d two-photon transition of sodium which are due to the 4d hyperfine splitting. The A -factors of the 23 Na 4d states were determined: A( 2 D 3 2 ) = + 215 (15) kHz , A( 2 D 5 2 ) = + 29 (6) kHz .

The hyperfine structure of Am atoms was investigated in an atomic beam by laser spectroscopy. The observed splittings were evaluated with respect to the magnetic dipole and electric quadrupole moments of242mAm. The results are: μ I (242mAm)=+0.97(5)nm,Q(242mAm)=+6.5(2.0)b.

The electronic transitions from the ground state to the 3d states have been studied for23Na and7Li atoms by two-photon Doppler-free laser spectroscopy. The positions of the resonances are used to determine the unresolved hyperfine structure of the 3d states from which the magnetic-dipole hyperfine interaction constantsA are derived. The results for theA factors are:A(3d 2 D 3/2;23Na)=+527(25) kHz;A(3d 2 D 5/2;23Na)=+108.5(2.4) kHz;A(3d 2 D 3/2;7Li)=+843(41) kHz;A(3d 2 D 5/2;7Li)=+343.6(1.0) kHz. For the fine structure intervals fs of the 3d doublets we obtain: fs(3d Na)=-1 494 444(44) kHz and fs(3d Li)=+1 083 936(60) kHz. The linewidths of the resonances are evaluated with respect to the natural lifetimes of the 3d states. For Na the result is τ(3d Na)=19.27(23) ns.

Systematic studies of the optical isotope shift and the hyperfine splitting of long chains of stable and radioactive isotopes were performed. The method applied was laser induced resonance absorption; the experimental techniques were the atomic beam method with fluorescence detection and the optogalvanic method. The theory of hyperfine splitting and isotope shift of atoms is reviewed in short with emphasis on the aspects interesting for nuclear physics and on the evaluation problem. The experimental methods are described and their key parameters sensitivity and resolution are discussed. Preliminary results on stored thorium ions are given. Sample results for the nuclear quantity δ derived from atomic beam experiments with tin and strontium are presented.

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.

To determine the accuracy to which hyperfine splittings can be measured using a cw dye laser with rf sideband tuning, a series of atomic beam experiments with59Co was performed. One hyperfine splitting of the first excited metastable atomic state was measured and compared with the results for the same splitting from magnetic rf resonance experiments. The uncertainty with the methods applied was found to be about 0.05 to 1% of the experimental linewidth in general; it is ±20 kHz or ±0.05% of the linewidth in the present Co experiment. The hyperfine splitting constants of the 3d 8 4p 2 F 7/2 state were found to beA=419.3(9) MHz,B=−77(17) MHz.

Isotope shifts of all the stable isotopes and the hyperfine splittings of 115Sn, 117Sn and 119Sn have been measured in the transitions 5s25p23P0-5s25p6s3P1 at 286 nm in Sn I. Tin atoms in a collimated beam to reduce the Doppler width were excited by radiation at 286 nm generated by frequency doubling the light from a CW ring dye laser. Spectra were recorded by monitoring the subsequent decay and calibrated by optical heterodyning. The relative positions of the isotopes are, in MHz: 112; 0.0(1.0), 114;319.5(1.3), 115;412.7(1.1), 116;640.0(0.6), 117;746.8(0.7), 118;945.2(0.7), 119;1039.3(1.1), 120;1214.4(0.5), 122;1448.5(0.7), 124;1656.0(0.7). The bracketed uncertainties are added in quadrature to give the errors of the isotope shifts. For odd-even shifts involving 112, 114, 120, 122 and 124 an extra 0.5 MHz must be added in quadrature. The hyperfine splitting factors of 5s25p6s3P1 are, in MHz: A(115)=-4395.4 (2.1), A(117)=-4790.71(1.7), A(119)=-5014.8(1.9). The results are interpreted in terms of the electronic and nuclear properties of the tin isotopes.

We give data of the isotope shift for the strontium isotopes from A=80 to A=90. They are found to be inconsistent with data from another optical transition. Possible reasons for the discrepancy are discussed.