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Resonance ionization mass spectrometry (RIMS) was used to obtain isotope and state selective information on Sr sputtered from metallic and biological matrices. In exploratory experiments Sr atoms were sputtered from bulk metal upon impact of 15 keV Ar+ ions, and probed by stepwise resonant ionization using two-color schemes. Efficient ionization schemes were selected to excite ground-state originating atoms into autoionizing states. Cross sections for photoionization were found to be up to the order of 10−15 cm2. The Sr content in bone fragments was probed utilizing these schemes. Even with minimal sample preparation, a detection limit of ±50ppm Sr in the hydroxiapatite-matrix of the bone was demonstrated, with isotope specificity. While this is inferior to detection limits normally associated with RIMS, these preliminary experiments were carried out for sputtering from untreated, non-conducting matrix materials.

For the analysis of actinide containing micron-size particles, a new experimental setup has been evaluated which uses sputtered neutral atoms instead of secondary ions. The atoms are post-ionized with lasers, either non-resonantly or resonantly. First experiments on non-resonant ionization of micron-size uranium oxide particles have shown that the sputter yields for secondary neutral atoms are much higher than for secondary ions, and uranium particles

Resonance ionization mass spectrometry (RIMS) was used to obtain state selective information on uranium atoms released from thin films by keV ion beam bombardment. First experiments were conducted to evaluate double-resonant laser ionization schemes. The high selectivity of such ionization schemes is further illustrated by comparing the flight-time distributions of the sputtered particles obtained both by resonant and non-resonant multiphoton (355 nm) laser post-ionization.

The electronic processes governing keV ion-beam sputtering of metals are studied by double resonance laser ionization mass spectrometry of the ejected metal atoms. We present the population partitions over the ground and metastable states of sputtered Cu and Sr atoms and their state-selective flight-time distributions. These results support the model indicating resonant electron transfer from the metal to the sputtered particle as a key mechanism to populate the electronic states.

One-color two-photon ionization spectroscopy was used to probe state-selectively neutral benzene molecules desorbed from a benzene overlayer physisorbed on a Ag{111} surface upon 8 keV Ar+ bombardment. Time distributions were measured for benzene molecules ejected in the zero level of the molecular ground state and in the first state of the ν6″ vibration. These distributions are found to show a strong dependence both on the internal energy of the ejected molecules and the degree of coverage of the Ag surface. Up to monolayer coverages, benzene molecules are ejected by direct collisions with Ag particles sputtered from the underlying substrate. Molecules with higher internal energy leave the surface with a distribution shifted towards lower flight times. At multilayer coverages, a second, thermal-like ejection mechanism gains significance. It is suggested that only molecules excited near the benzene-vacuum interface, survive the ejection process without being deexcited.

We report the measurement of state specific kinetic energy distributions of ground and metastable state Ni atoms ejected during 15 keV. Ar+ beam sputtering of clean polycrystalline Ni targets. A very sensitive experimental procedure based on double resonant laser ionization was used to measure a nearly complete set of kinetic energy distributions of the populated states. The state specific kinetic energy distributions and their weighted sum using the measured population partition provide further evidence for resonant electron tunneling during the emission process and its dependence on both the atomic electronic configuration and the bulk electronic structure.

We present the development of a sensitive method for the study of atomization processes via the metastable state population and kinetic energy distributions of sputtered atoms, including atoms on high-lying metastable electronic states. The experimental procedure is based on two-colour two-step resonant photoionization. We report on the population distribution of Ar ion sputtered Ni and Co atoms. The measurements show unexpectedly high populations on metastable states with energies above 1.5 eV. The kinetic energy distributions of Ni atoms on such states support the importance of bandstructure effects in the excitation mechanism of atoms after ion beam sputtering.

First results obtained with a new type of an element‐selective laser ion source for an on‐line mass separation are presented. The concept of the ion source is based on laser resonance ionization of nuclear reaction products thermalized in a high‐pressure noble gas. The fast and universal thermalization of reaction products in combination with high selectivity and high efficiency of resonance photo ionization allows to develop an element‐pure source of short lived exotic nuclei.