J. Mathias Weber

My group combines mass spectrometry with laser spectroscopy to characterize positively and negatively charged ions and biomolecules. One project is concerned with infrared spectroscopy of molecular and metal containing cluster ions. These are produced in a pulsed supersonic expansion, and mass selected in a time-of-flight mass spectrometer. Photons absorption leads to evaporation of weakly bound ligands from the cluster. The absorption spectra of the clusters under study can be measured by monitoring the generation of photofragments as a function of the laser wavelength. In a second project, we are developing a three-stage photofragmentation spectrometer that uses an electrospray ion source to deliver ions into an ion trap (Step 1). There, the ions can be cooled or reacted with small solvent molecules such as water. Next, the products from Step 1 are mass selectred and illuminated with tunable pulsed laser light (Step 2). Finally, the light-induced photofragments are analyzed by means of a time-of-flight spectrometer (Step 3). This system will allow us to study the spectral and dynamical differences between unsolvated, sequentially solvated, and solution phase ion species. In the future, we plan to use it to investigate the photo physics and chemistry of structurally and/or electronically complex molecules such as multiply charged anions, cationic and anionic salt cluster ions, and charged biomolecules.