Auger–Meitner and X-ray Absorption Spectra of Ethylene Cation: Insight into Conical Intersection Dynamics

Abstract

We present a theoretical investigation of the near-edge X-ray absorption fine structure and the Auger−Meitner decay spectra of ethylene and its cation. Herein, we demonstrate that our method, coupled with the nuclear ensemble approach, successfully reproduces the natural bandwidth structure of the experimental resonant Auger−Meitner decay spectra of ethylene, which is not very well reproduced within the Franck−Condon approximation. Furthermore, we analyze the Auger−Meitner decay spectra of the ethylene cation in light of minimum energy conical intersection structures involving the two lowest cationic states (D 1 and D 0 ), providing valuable insights into the ultrafast D 1 /D 0 relaxation dynamics. Our results suggest that Auger−Meitner electron spectroscopy can help elucidate the mechanism behind the initial 20 fs of the relaxation dynamics.

Influence of Selective Carbon 1s Excitation on Auger–Meitner Decay in the ESCA Molecule

“…Recently, time-resolved AM spectroscopy was proposed to settle a debate on the mechanism of ultrafast internal conversion in the ethylene cation to provide a more structurally sensitive probe than previous XAS studies. 13 , 42 Future theoretical studies may verify our findings by employing the one-center approximation, which evaluates absolute decay rates with atomic integrals and can produce results in good agreement with experiment. 33 Furthermore, the inclusion of dynamic correlation via PT2 is a major computational bottleneck and prevents a full-spectrum decay calculation.…”

“…This demonstrates a high sensitivity of the resonant AM decay signal to specific structural regions of polyatomic molecules. This could enable functional group selectivity in future time-resolved resonant AM decay studies of excited-state dynamics. − …”

Virtual Special Issue on Attosecond Chemistry

“…Auger–Meitner electron spectroscopy is also helpful in elucidating the mechanism beyond ultrafast molecular relaxation dynamics when correlated with appropriate theoretical models. Cabral Tenorio et al have successfully reproduced the bandwidth structure of resonant Auger–Meitner decay spectra in ethylene, providing valuable insights into the ultrafast relaxation dynamics involving the two lowest cationic states …”