Core-Level Spectroscopy Decodes Bond-Alternation Dynamics of Cyclo[18]Carbon
Abstract
The advent of X-ray free-electron lasers and high-harmonic generation has made time-resolved X-ray spectroscopy a powerful tool for probing local atomic environments, yet whether localized core excitations can report on global collective distortions remains open. Cyclo[18]carbon (C18), with its polyynic ground state (D9h) and cumulenic transition state (D18h), provides an ideal model to address this long-standing issue in bond-length alternation (BLA) dynamics. Mapping two-dimensional potential energy surfaces by first-principles simulations, we find that core ionization symmetrizes the ground-state double-well potential along the BLA coordinate. Our calculated X-ray spectra reveal remarkable sensitivity to bond-length variations: C1s ionization potentials vary by up to 2.4~eV across the BLA coordinate (1.1--1.4~Å), with a 0.9~eV variation for minima predicted by different functionals, while NEXAFS π* peaks shift by up to 4~eV across the same coordinate. These predicted signatures provide a quantitative spectroscopy--structure dictionary for decoding transient structures in future ultrafast X-ray experiments and monitoring bond-alternation dynamics in real time.
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BibTeX
@misc{wei2026corelevel,
title = {{Core-Level Spectroscopy Decodes Bond-Alternation Dynamics of Cyclo[18]Carbon}},
author = {Minrui Wei and Zeyu Liu and Sheng-Yu Wang and Jun-Rong Zhang and Lu Zhang and Guoyan Ge and Weijie Hua},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.06916},
eprint = {2609.06916},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.06916},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Core-Level Spectroscopy Decodes Bond-Alternation Dynamics of Cyclo[18]Carbon
AU - Minrui Wei
AU - Zeyu Liu
AU - Sheng-Yu Wang
AU - Jun-Rong Zhang
AU - Lu Zhang
AU - Guoyan Ge
AU - Weijie Hua
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.06916
UR - https://arxiv.org/abs/2609.06916
AB - The advent of X-ray free-electron lasers and high-harmonic generation has made time-resolved X-ray spectroscopy a powerful tool for probing local atomic environments, yet whether localized core excitations can report on global collective distortions remains open. Cyclo[18]carbon (C_18), with its polyynic ground state (D_9h) and cumulenic transition state (D_18h), provides an ideal model to address this long-standing issue in bond-length alternation (BLA) dynamics. Mapping two-dimensional potential energy surfaces by first-principles simulations, we find that core ionization symmetrizes the ground-state double-well potential along the BLA coordinate. Our calculated X-ray spectra reveal remarkable sensitivity to bond-length variations: C1s ionization potentials vary by up to 2.4~eV across the BLA coordinate (1.1--1.4~Å), with a 0.9~eV variation for minima predicted by different functionals, while NEXAFS π^* peaks shift by up to 4~eV across the same coordinate. These predicted signatures provide a quantitative spectroscopy--structure dictionary for decoding transient structures in future ultrafast X-ray experiments and monitoring bond-alternation dynamics in real time.
ER -