UV and IR Spectroscopy of Cryogenically Cooled, Lanthanide-Containing Ions in the Gas Phase

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• 作者：Yoshiya InokuchiMasashi Kaneko ; Takumi Honda ; Satoru Nakashima ; Takayuki Ebata ; Thomas R. Rizzo
• 刊名：Inorganic Chemistry
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：56
• 期：1
• 页码：277-281
• 全文大小：312K
• ISSN：1520-510X

文摘

We measure UV and IR spectra in the gas phase for EuOH⁺, EuCl⁺, and TbO⁺ ions, which are produced by an electrospray ionization source and cooled to ∼10 K in a cold, 22-pole ion trap. The UV photodissociation (UVPD) spectra of these ions show a number of sharp, well-resolved bands in the 30000–38000 cm^–1 region, although a definite assignment of the spectra is difficult because of a high degree of congestion. We also measure an IR spectrum of the EuOH⁺ ion in the 3500–3800 cm^–1 region by IR–UV double-resonance spectroscopy, which reveals an OH stretching band at 3732 cm^–1. We perform density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations of these ions in order to examine the nature of the transitions. The DFT results indicate that the states of highest-spin multiplicity (octet for EuOH⁺ and EuCl⁺ and septet for TbO⁺) are substantially more stable than other states of lower-spin multiplicity. The TD-DFT calculations suggest that UV absorption of the EuOH⁺ and EuCl⁺ ions arises from Eu(4f) → Eu(5d,6p) transitions, whereas electronic transitions of the TbO⁺ ion are mainly due to the electron promotion of O(2p) → Tb(4f,6s). The UVPD results of the lanthanide-containing ions in this study suggest the possibility of using lanthanide ions as “conformation reporters” for gas-phase spectroscopy for large molecules.