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Spectroscopic Signature of the Oxygen States in Peroxides



Zengqing Zhuo, Chaitanya D. Pemmaraju, John Vinson, Chunjing Jia, Brian Moritz, Ilkyu Lee, Shawn Sallies, Qinghao Li, Jinpeng Wu, Kehua Dai, Yi-De Chuang, Zahid Hussain, Feng Pan, Thomas P. Devereaux, Wanli Yang


Recent debates on the nonconventional oxygen behaviors in electrochemical devices have triggered a pressing demand of a reliable detection and understanding of non-divalent oxygen states beyond conventional oxygen absorption spectroscopy. Here, enabled by high-efficiency mapping of resonant inelastic X-ray scattering (mRIXS) and coupled with first- principles calculations, we provide a comprehensive experimental and theoretical study of the oxygen states in Li2O, Li2CO3, and especially, Li2O2. mRIXS reveals distinct oxygen features in the three compounds, which could be successfully reproduced and interpreted by theoretical calculations. mRIXS signals are dominated by decays of valence-band electrons in Li2O and Li2CO3. However, the oxidized oxygen in Li2O2 leads to a low- energy unoccupied state that triggers a specific excitonic feature in mRIXS. This work concludes that the critical mRIXS feature of Li2O2 stems from O 2p intra-band excitations due to the partially occupied 2p states. Such a mechanism based on excitations are universal for partially occupied oxygen 2p states, which provides critical hints for both detecting and understanding the fundamental mechanism of the oxidized oxygen in the electrochemical materials that are currently under active debates.
Journal of Physical Chemistry Letters


Zhuo, Z. , Pemmaraju, C. , Vinson, J. , Jia, C. , Moritz, B. , Lee, I. , Sallies, S. , Li, Q. , Wu, J. , Dai, K. , Chuang, Y. , Hussain, Z. , Pan, F. , Devereaux, T. and Yang, W. (2018), Spectroscopic Signature of the Oxygen States in Peroxides, Journal of Physical Chemistry Letters, [online],, (Accessed June 13, 2024)


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Created October 15, 2018, Updated October 12, 2021