New Insights in 4f125d1 Excited States of Tm2+ through Excited State Excitation Spectroscopy

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• 作者：Mathijs de Jong ; Daniel Biner ; Karl W. Krämer ; Zoila Barandiarán ; Luis Seijo ; Andries Meijerink
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：July 21, 2016
• 年：2016
• 卷：7
• 期：14
• 页码：2730-2734
• 全文大小：373K
• 年卷期：0
• ISSN：1948-7185

文摘

Optical excitation of ions or molecules typically leads to an expansion of the equilibrium bond lengths in the excited electronic state. However, for 4f^n–15d¹ excited states in lanthanide ions both expansion and contraction relative to the 4fⁿ ground state have been reported, depending on the crystal field and nature of the 5d state. To probe the equilibrium distance offset between different 4f^n–15d¹ excited states, we report excited state excitation (ESE) spectra for Tm²⁺ doped in CsCaBr₃ and CsCaCl₃ using two-color excited state excitation spectroscopy. The ESE spectra reveal sharp lines at low energies, confirming a similar distance offset for 4f^n–15d(t_2g)¹ states. At higher energies, broader bands are observed, which indicate the presence of excited states with a different offset. On the basis of ab initio embedded-cluster calculations, the broad bands are assigned to two-photon d–d absorption from the excited state. In this work, we demonstrate that ESE is a powerful spectroscopic tool, giving access to information which cannot be obtained through regular one-photon spectroscopy.