New electron-photon coincidence technique using enhanced photon detection probabilities

Electron and photon spectroscopy were used to investigate correlative processes in heterogeneous systems. These results clearly show a strong interaction between different compounds of these systems, where one compound acts as an antenna for efficient absorption of energy which is transported to the other compound. The excess energy is used ionize the second compound.

Color-coded electron spectrum as function of the exciting-photon energy and the electron binding energy in the case of Ar-Ne clusters.
(a) Color-coded electron spectrum as function of the exciting-photon energy and the electron binding energy in the case of Ar-Ne clusters.

We show that networks of loosely bound noble gases, so-called clusters, drastically change their reaction on the excitation with light of narrow bandwidth if a small amount of another noble gas is added into this network. For this purpose, we combined complementary photon and electron measurements to illustrate the reduction of the photon emission by a competing electron emission process due to the interaction of the different binding partners.  In the experiment, first pure neon clusters were resonantly excited below their ionization threshold. These clusters relax by the re-emission of photons, i.e. radiatively. 

The addition of argon atoms into the neon network however allows the emission of an electron since the ionization of argon is lower than the energy stored in the neon. Therefore, no photon emission occurs anymore as the absorbed energy is now used to emit an electron from the argon atoms. 

The neon atoms work as an antenna for exciting-photons with energies in vicinity of the neon cluster resonances and transfer the energy to the argon atoms leading to a strongly enhanced ionization probability than for pure argon clusters at corresponding energies.


A. Hans et al. The Journal of Physical Chemistry Letters 10 1078 (2019)

DOI: 10.1021/acs.jpclett.9b00124

Andreas Hans @ AGE – Spectroscopy