Bonn 2025 – scientific programme
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SYAD: Symposium SAMOP Dissertation Prize 2025
SYAD 1: SAMOP Dissertation Prize Symposium
SYAD 1.3: Invited Talk
Monday, March 10, 2025, 15:30–16:00, HS 1+2
How rotation shapes the decay of diatomic carbon anions — •Viviane C. Schmidt — Max-Planck-Institut für Kernphysik, Heidelberg, Germany
Molecules that are internally highly excited play an important role in a range of fields from atmospheric to plasma physics. Modelling such systems requires a detailed understanding of the molecules’ behaviour under these extreme conditions. However, this is a non-trivial task due to the high density of excited states as well as the variety of competing decay mechanisms available. The diatomic carbon anion C2− presents an excellent benchmark to understand the interplay of different decay channels at high internal excitation. The system is arguably the most extensively studied molecular anion in history. Yet, its decay behaviour at high internal excitation has long remained a puzzle for physicists. When produced in a hot ion source, a subset of the resulting anions spontaneously eject their excess electron with a very narrow lifetime span of about 3 ms. While this autodetachment phenomenon has been known since the 1990s, the responsible anionic excited states and their decay mechanism have long remained elusive. Based on our measurements of autodecay of highly excited C2− at the Cryogenic Storage Ring (CSR) facility in Heidelberg, we carried out detailed calculations of the excited states and their decay behaviour. Here, we were able to uncover the profound effect rotational excitation has on the system’s electronic landscape. This in turn alters the available decay channels at high excitations and enabled the discovery of a new autodetachment mechanism, which explains the measured feature.
Keywords: Molecular Physics