DESIREE electrospray ion source test bench and setup for collision induced dissociation experiments

Non-statistical fragmentation in photo-activated flavin mononucleotide anions

The spectroscopy and photo-induced dissociation of flavin mononucleotide anions in vacuo are investigated over the 300-500 nm wavelength range. Comparison of the dependence of fragment ion yields as a function of deposited photon energy with calculated dissociation energies and collision-induced dissociation measurements performed under single-collision conditions suggests that a substantial fraction of photo-activated ions decompose through non-statistical fragmentation pathways. Among these pathways is the dominant photo-induced fragmentation channel, the loss of a fragment identified as formylmethylflavin. The fragment ion specific action spectra reveal electronic transition energies close to those for flavins in solution and previously published gas-phase measurements, although the photo-fragment yield upon excitation of the S₂ ← S₀ transition appears to be suppressed.

Ion optics simulation of an ion beam setup coupled to an electrospray ionization source, strengths, and limitations

A unified approach to achieve a start-to-end ion optics simulation of an ion beam apparatus coupled to an electrospray ionization source is presented. We demonstrate that simulations enable reliable information on the behavior and operation of the apparatus to be obtained, but due to the collisions with the buffer gas in the initial stages of the setup, the results concerning the kinetic energy of the ion beam must be treated with care.

A cryogenic linear ion trap beamline for providing keV ion bunches

A new cryogenic linear ion trap beamline has been constructed and commissioned, which serves to inject cold molecular and cluster ions into the RIKEN cryogenic electrostatic ring (RICE). Ions are created with an electrospray ion source, and a quadrupole mass filter is used for mass-selection prior to trap injection. The radio frequency octupole ion trap can be continuously loaded with ions and features a fast ion extraction mode to create short ion bunches with tens of μs duration. We report here on the simulations and development of the ion trap beamline and validate performance with the moderately heavy molecular cation methylene blue. Characterization of the novel trap design with additional wedge-shaped electrodes was carried out, which includes the determination of the temporal and spatial shape of the ion bunch and the total number of ions after extraction. Finally, these ion bunches are synchronized with the switching of a pulsed high-voltage acceleration device downstream of the trap, where the ions obtain a kinetic energy of up to 20 keV. The preparation and control of the keV ion beam are demonstrated for the ion injection into RICE.