BerlinTrap description

The BerlinTrap, equipped with a cryogenic 22-pole ion trap and an electrospray ion source, is a tool used for advanced molecular spectroscopy. It employs helium buffer gas cooling to achieve low ion temperatures, enhancing the precision of studies. In its first experiments, the BerlinTrap analyzed the VISPD spectrum of cold protonated lumichrome ions, with quantum chemical simulations aiding in understanding the molecule's behavior and characteristics. The apparatus cooled ions to temperatures below 30 K, ensuring a vibrationally resolved spectrum.

I assisted in calibrating the experiment and implementing a dye laser for spectroscopy, both programmatically and physically. Using the BerlinTrap, I recorded the first optical spectrum of a flavin molecule in the gas phase and analyzed the VISPD spectrum of cold H⁺LC ions. Comparison with quantum chemical simulations revealed insights into the ions' geometrical, vibrational, and electronic properties. The BerlinTrap's ability to cool ions below 30 K eliminated hot band transitions, yielding a detailed electronic spectrum. I used TD-DFT and multidimensional FC simulations for a comprehensive structural, vibrational, and electronic assignment, forming the core of my M.Sc. thesis in physics and leading to several publications.

BerlinTrap schematic

The schematic diagram illustrates the intricate design and operation of the BerlinTrap apparatus. Ions are initially produced within an Electrospray Ionization (ESI) source. Post-generation, they are accumulated in a mini-quadrupole (miniQP) before being transferred through a hexapole (HP) ion guide to a quadrupole mass spectrometer (QPMS) for mass selection.

The apparatus is equipped with an electrostatic quadrupole bender (B) that directs the ions either towards a channeltron ion counter (CT) or into a cryogenic 22-pole trap that is mounted on a cryostat (Cryo), facilitated by an octupole ion guide (OP). This cryogenic 22-pole trap is instrumental in the cooling and analysis of ions, a process that is integral to the precision of the spectroscopic studies conducted.

In the context of specific experiments, such as the analysis of protonated lumichrome, the ions within the cryogenic trap are subjected to tagging and/or laser illumination, depicted by the red line in the schematic. This process is crucial for the detailed analysis of the ions’ behavior and characteristics.

Following the tagging or laser illumination, the ions’ products are focused using the einzel lens deflector (ELD) into the acceleration region of the reflectron time-of-flight spectrometer (ReTOF). This component of the BerlinTrap is essential for the precise ion analysis, as evidenced in studies where it was employed to achieve a vibrational temperature below 20 K, ensuring accurate spectroscopic data.

Publications