A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity was applied for study of short‐lived tin isotopes at the heavy ion accelerator UNILAC/GSI. Tin atoms were ionized by a three‐step resonance laser excitation of an autoionizing state. Yields of fusion‐produced 108Sn and 108In isotopes were compared with the plasma ion source FEBIAD‐B3. The total efficiency of tin ionization was determined to be 8.5%, whilst the indium isobar ionization was suppressed by a factor of 12. An experimental run on study of decay properties of extremely neutron deficient isotopes 101–103Sn has been carried out.

Trace analysis of long‐lived isotopes of technetium and plutonium requires a very sensitive and selective detection method. A laser ion source (LIS) based on resonance ionization spectroscopy with subsequent mass analysis (RIMS) offers these properties. Measurements with an ion source made of extremely pure pyrolytically coated graphite are discussed. Photoionization of 99Tc has been measured with a LIS efficiency of 4×10−3 leading to an extrapolated detection limite of 5×106 atoms. The elements selectivity depends on the working temperature of the cavity and varies from 1×104 (1860 K) to 8×10−2 (2130 K).

The very neutron-deficient isotope 101Sn was produced in a 50Cr(58Ni, 2p5n) reaction and its decay properties were determined for the first time. By using chemically selective ion sources of an on-line mass separator, the energy spectrum and the half-life (3 ± 1 s) of beta-delayed protons of 101Sn were measured. These results are compared to theoretical predictions.

Resonance ionization of atoms confined in a hot cylindrical cavity is a very efficient and selective technique for trace analysis. Several applications of this method have been tested or are presently under investigation. An efficiency of 14% was obtained for technetium. An efficient path for rnance ionization of tin was found, leading to an autoioniing state at 59375.9 cm1. The high efficiency makes the baer ion source suitable for trace analysis of actinides in the environment. In all cas surface-ionized background has to be suppresoed to avoid isobaric interferences. Therefore a new laser ion source has been developed with a cavity made ofextremely pure pyrolytically coated graphite.

Trace amounts of plutonium are detected, by means of resonance ionization mass spectroscopy (RIMS). A three-step excitation scheme leading to an autoionizing state is used for the detection of trace amounts of Pu-239 down to 10(7) atoms. The isotope shifts (IS) of different plutonium isotopes were measured for several excitation schemes. Taking into account the isotope shifts a good reproducibility of the isotopic abundances is obtained with RIMS. In order to increase the detection efficiency a reflectron time-of-flight (TOF) mass spectrometer was built and tested with gadolinium.

Resonance ionization mass spectroscopy (RIMS) is a very element-selective and sensitive analytical technique for the detection of trace elements. This method is based on the stepwise excitation and ionization of atoms with resonant laser light and followed by mass analysis. Our facility for RIMS consists of three dye lasers, pumped by two copper vapor lasers, and a linear time-of-flight spectrometer. For trace analysis of neptunium several two- and three-step excitation schemes have been investigated for maximum detection efficiency. With one of the schemes an overall efficiency of 3 x 10(-8) was reached resulting in a detection limit of 4 x 10(8) atoms (160 fg) of neptunium. Furthermore, the first ionization potential of neptunium was measured to be I = 6.2656(4) eV.

An efficient three-colour, three-step resonant excitation/ionization scheme has been found for tin that leads from the 5p23P2 level of the ground-state multiplet via two excited atomic levels (λ1 = 317.51 nm and λ2 = 811.40 nm) to an autoionizing state 9s3P2(λ3 = 823.49 nm) at 59375.9 cm−1. This excitation path permits the saturation of all transitions with the limited power available from a copper vapour laser pumped dye laser system (Esat ≈ 1.5 mJcm2 for λ3). The high repetition rate of such a laser system is essential for a highly efficient laser ion source.