Anions and photoelectrons

Investigation of electronic dark states through anion photoelectron spectroscopy

The goal of this project is a direct spectroscopic access to excited electronic states of neutral molecules or neutral molecule complexes, which are only poorly visible in neutral spectroscopy, due to electronic selection rules.

Electronic dark states are

Triplet states T₁, T₂
Charge transfer states (inter-and intra-molecular)
nπ* states
symmetry-forbidden states

Direct excitation from the anion often bypasses many transition restrictions existing in neutral optical spectroscopy. Therefore, many of these iso-called "forbidden" states are accessible for the first time.

MO-Schema — Figure 1: MO scheme and scheme of the electronic states: triplet states and other excited electronic states can be achieved by removing a suitable electron.

Construction of apparatus:

Unbenannt5 — Figure 2: Experimental setup: The anions generated by electron attachment and cooled in a supersonic jet. They are accelerated and separated in a linear time of flight mass spectrometer according to mass. A Bender allows either the start of mass spectra or the recording of photoelectron spectra in a magnetic bottle.

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