Ar2 photoelectron spectroscopy mediated by autoionizing states.

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Chemical Physics

Background:

• Autoionization dynamics in van der Waals clusters like Ar(2) are complex.
• Understanding these dynamics is crucial for probing electronic structures.
• Previous studies faced limitations in observing complete vibrational progressions.

Purpose of the Study:

• To investigate the autoionization dynamics of Ar(2) clusters below the ionization energy of atomic argon.
• To develop and apply a novel experimental method for analyzing photoelectron spectra.
• To characterize the vibrational states of Ar(2)(+) and autoionizing states.

Main Methods:

• Irradiation of Ar(2) clusters with vacuum ultraviolet (VUV) radiation.
• Coincidence detection of photoelectrons and cluster ions.
• Application of a newly developed analysis technique for photoelectron signals.
• Photon energy dependence studies to reveal ionization dynamics.

Main Results:

• Observed the complete vibrational progression of Ar(2)(+), including the previously elusive 0-0 transition.
• Overcame Franck-Condon limitations in single photoionization.
• Obtained projections of autoionizing state vibrational wave functions onto Ar(2)(+) functions.
• Validated the experimental method's power in characterizing autoionization.

Conclusions:

• The developed method offers unprecedented insight into Ar(2) autoionization dynamics.
• The results provide a robust dataset for testing theoretical calculations of Rydberg states.
• This work advances the understanding of cluster autoionization and its relation to electronic structure.