1990 HELMHOLTZ PRIZE (award ceremony on 19 March 1990)

Prof. Dr. Heinz-Jürgen Kluge, Prof. Dr. Norbert Trautmann for the work "A resonance ionization mass spectrometer as an analytical instrument for trace analysis"


1990 Prizewinners: A resonance ionization mass spectrometer for trace analysis

Heinz-Jürgen Kluge (left), born in Sorau (Lower Lusatia) in 1941, studied physics from 1960 to 1967, first in Bonn and then in Heidelberg, where he received his doctorate in 1970. As a post-doctoral fellow and also later, he carried out research at CERN. In 1972, he went to the University of Mainz, where he habilitated in 1975 and became a professor for experimental physics in 1978. At CERN, he was the head of the ISOLDE Physics Group from 1985 to 1987. In 1994, he followed a call to the University of Heidelberg. From 1999 to 2005, he was the Research Director of GSI in Darmstadt. He retired in 2007. He was awarded the Lise Meitner Prize for Nuclear Science (2006), the IIUPAP Senior Scientist Medal in Fundamental Metrology (2008), the Flerov Prize (2013) and the Robert Wichard Pohl Prize (2020).


Norbert Trautmann (right) was born in Straubing in 1939. From 1958 to 1964, he studied chemistry at the University of Mainz, where he received his doctorate in 1968, with Fritz Strassmann as one of the two reviewers. From 1970 to 1971, he was a postdoctoral fellow under Seaborg and Ghiorso at the Lawrence Berkeley Laboratory. In 1971, he returned to Mainz where he was first the deputy manager – and from 1991 to 2005 – the manager of the research reactor TRIGA Mainz. In 1981, he started his collaboration with H.-J. Kluge, which led to the development of resonance ionization mass spectrometry (RIMS). For his scientific achievements, he received several awards, like the Fritz Strassmann Award  (1984), the Otto Hahn Award of the City of Frankfurt/Main (1998), the Glenn T. Seaborg Award for Nuclear Chemistry (2007), the Order of Merit of the State Rhineland-Palatinate (2010) and the Medal of Merit of the Johannes Gutenberg University Mainz (2019). He retired in 2005.

The detection of extremely small quantities of toxic or radioactive substances is an important task for "Physical Measurement Technology in Medicine and Environmental Protection”. This is the research area in which the physicist Prof. Dr. Heinz-Jürgen Kluge and the chemist Prof. Dr. Norbert Trautmann, both from the University of Mainz, were honoured with the 1990 Helmholtz Prize for their interdisciplinary work "A resonance ionization mass spectrometer as an analytical instrument for trace analysis".

The instrument they developed combined the advantages of mass spectrometry and the resonant excitation and ionization of atoms by laser light for highly sensitive element- and isotope-specific detection. In this way, a detection limit of 2 ∙ 106 atoms could be achieved for the radioactive isotope plutonium-239, corresponding to 8 ∙ 10-16 grams. Thus, this method was two orders of magnitude more sensitive than α-spectroscopy, which detects plutonium-239 via its α-decay.

The work of Kluge and Trautmann was based on the idea of first exciting and then ionizing the atoms of the element or isotope under investigation in three successive steps, so that the resulting ions could then be separated and detected with a mass spectrometer. For the excitation and ionization of the atoms, three pulsed and tunable dye lasers were used. Since the atoms were excited resonantly in the first two steps, the probability of ionizing interfering substances was very small (about 10-10).

The atoms, ionized in pulses, could be separated isotopically using a time-of-flight mass spectrometer. The two researchers demonstrated this using the example of the seven naturally occurring isotopes of gadolinium, where the mass resolution MM was 2700. If the resonant excitation was tuned to a specific isotope, this isotope could be selectively ionized and detected, while other isotopes were strongly suppressed, as verified with plutonium. Thus, the determination of the isotopic composition of plutonium in an environmental sample made it possible to distinguish between reactor plutonium and nuclear fallout.

Since the 1990s, resonance ionization mass spectrometry has found many applications as a sensitive trace detection technique for actinides and other elements contained in environmental or biological samples and for determining nuclear ground state properties of isotopes produced by accelerators, for example at CERN.


H.-J. Kluge and N. Trautmann: Ein Resonanzionisations-Massenspektrometer als analytisches Instrument für die Spurenanalyse. PTB-Mitteilungen 100, (1990), 251