Current News

The COLLAPS paper on the charge radii measurements along the magnesium chain has been published as an article in Physical Review Letters. Charge radii along this chain are of particular interest since neutron-deficient isotopes exhibit a cluster-like structure, whereas the neutron-rich isotopes show the transition into the so-called "island of inversion". The radii could only be investigated since we employed for the first time laser-optical pumping combined with particle-sensitive beta-asymmetry detection for isotope shift measurements. This was only possible after a detailled and quantitative understanding of the pumping process and the resulting lineshape was obtained, as it was carried out at COLLAPS  over the last couple of years.
The article is available online … >

Surprisingly, in cold interstellar clouds, hydrogen cyanide, HCN, and the considerably more energetic isomer of hydrogen cyanide, HNC (hydrogen isocyanide), have nearly equal abundance.
In a just in Astrophysical Journal Letters online published article Mario B. Mendes et al. report on experiments that provide an explanation for this phenomenon. These experiments have been performed by the group "Molecular quantum dynamics and stored ion beams" around Andreas Wolf with the ion storage ring at the Max Planck Institute for Nuclear Physics in Heidelberg.

Please read more in the article ... >

Detailed information in the press release of the MPIK 

Even after 35 years of activity and despite enormous advances in computers and experimental methods, the spectrum of the smallest triatomic molecular system, the H₃⁺ ion, at higher excitations has remained an enigma neither fully accessed experimentally nor fully elucidated theoretically.

In a just in Physical Review Letters published article M. Pavanello et al. report on new developments that overcome the experimental and theoretical difficulties that occur beyond the barrier to linearity and largely unveil the elusive, highly excited H₃⁺ spectrum.
Experimentally, at the MPI for Nuclear Physics, the sensitivity of ion trap spectroscopy on H₃⁺ has been increased, which now allows to measure the frequencies of ro-vib transitions extending far into the visible spectral range.
The new, precisely measured overtone frequencies gave decisive hints to an international group of molecular theorists on how to dramatically improve their first-principles quantum calculations of this fundamental triatomic molecule. They could obtain a model which reproduces the new observations precisely and is capable of describing the full ro-vib spectrum of H₃⁺.
The described work provides the most accurate global ground-state H₃⁺ potential energy surface (PES) available to date. Together with a simple model for nonadiabatic effects, it is now able to predict the ro-vib transitions of H₃⁺ with unprecedented accuracy.

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Detailed information also in the press release of the MPIK  and the IDW 

Although at first sight it seems very unlikely, negatively charged hydrogen molecules (H₂^– ions) can be metastable with a lifetime of a few microseconds. Experiments of the group "Molecular quantum dynamics and stored ion beams" of Andreas Wolf showed how hydrogen molecules can hold on to an extra electron for several microseconds. These molecule ions are rapidly rotating, they are very large and are finally decaying into neutral hydrogen molecules. The experimental results have just been published in Physical Review Letters. They confirm theoretical predictions.

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Detailed information also in the press release of the MPIK  and the reports of APS Physics  and Physics Today .

The time-of-flight (TOF) ion-cyclotron-resonance (ICR) technique for the mass determination of short-lived nuclides has recently been improved by the replacement of the quadrupolar excitation by an octupolar excitation of the ion motion. In a just in Physical Review Letters published article S. Eliseev et al. present the first analytical description of this novel octupolar technique and report on its application for a direct Penning-trap mass-ratio determination of the ¹⁶⁴Er-¹⁶⁴Dy mass doublet.
The new technique provided an increase in resolving power by more than an order of magnitude and, thus, allowed a simultaneous measurement of the cyclotron frequencies of ¹⁶⁴Dy⁺ and ¹⁶⁴Er⁺. ¹⁶⁴Er is a promising candidate for a search for neutrinoless double-electron capture. An observation of this neutrinoless transition would prove that the neutrino is a Majorana particle. The measured Q_ee value of 25.07(12) keV for ¹⁶⁴Er results in a half-life of 1030 years for a 1 eV mass of a Majorana neutrino.

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