Research

We use an efficient and alternative method to the commonly used RF-multipole trap technique to produce He-tagged molecular ions at cryogenic temperatures, which are perfectly suitable for messenger spectroscopy. The seeding of dopant ions in multiply charged helium nanodroplets, in combination with a gentle extraction of the latter from the helium matrix, enables the efficient production of He-tagged ion species. With a quadrupole mass filter, a specific ion of interest is selected, merged with a laser beam, and the photoproducts are measured in a time-of-flight mass-spectrometer. The detection of the photofragment signal from a basically zero background is much more sensitive than the depletion of the same amount of signal from precursor ions, delivering high quality spectra at reduced data acquisition times. 

Publication: S. Bergmeister, et al., Rev. Sci. Instrum. 94, 055105 (2023)

A multireflectron time-of-flight (MR-ToF) is a mass spectrometer that has been in use for several decades. Due to its low cost and high mass resolution, it is a very popular choice when accurate mass determination is required. One of seven MR-ToFs, which were developed and built as part of a collaboration between the University of Darmstadt and the University of Greifswald, is now in operation in one of our laboratories. In addition to the advantages already mentioned, the MR-ToF also impresses with its versatility. At the moment we are using the multireflectron to capture and store helium nanodroplets (HNDs). Future plans for this device include implementing a laser to obtain time-resolved spectroscopy of dopants embedded in the HNDs (pump-probe experiments), as well as observing fluorescence, measuring reaction kinetics and also changing the experimental setup to take advantage of the high mass resolving power of the device.

Publication: M. Veternik, et al., Phys. Rev. Lett. 136, 013201 (2026)