Yet another breakthrough for researchers at DESIREE!
An international collaboration led by Mark H. Stockett (Fysikum) and James N. Bull (University of East Anglia) last week published results from experiments conducted at the DESIREE infrastructure at Fysikum in Nature Communications. After decades of speculation and searching, astronomers have recently begun to identify complex Polycyclic Aromatic Hydrocarbon (PAH) molecules in interstellar clouds.
However, these discoveries have revealed gaping chasms in our understanding of the chemistry in these extreme environments. For example, the abundance of cyanonaphthalene (C10H7CN CNN), the largest hydrocarbon yet identified in space, is under-predicted in astrochemical models by more than six orders of magnitude [McGuire et al. Science 371 1265 (2021)]. Stockett et al. found that part of this astronomical discrepancy can be attributed to the model’s neglect of radiative stabilization of CNN following ionizing collisions by Recurrent Fluorescence (RF) – the emission of optical photons from thermally excited electronic states.
The team, which included several Fysikum researchers, pioneered a new technique for determining absolute dissociation and RF stabilization rates by analyzing the kinetic energy release distributions of the fragments emitted when highly-excited CNN ions disintegrated. Crucially, the authors found that the RF rate is boosted by more than two orders of magnitude by Herzberg-Teller vibronic coupling. These groundbreaking results call for reconsideration of long-standing hypotheses regarding the resilience of small PAH molecules in space. A follow-up article has been accepted for publication in Faraday Discussions.
Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds - Nature Communications
Last updated: February 2, 2023