Interplay between Temperature-Activated Vibrations and Nondipolar Effects in the Valence Excitations of the CO2 Molecule

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• 作者：Juho Inkinen ; Johannes Niskanen ; Arto Sakko ; Kari O. Ruotsalainen ; Tuomas Pylkk盲nen ; Szabolcs Galambosi ; Mikko Hakala ; Giulio Monaco ; Keijo H盲m盲l盲inen ; Simo Huotari
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：May 8, 2014
• 年：2014
• 卷：118
• 期：18
• 页码：3288-3294
• 全文大小：322K
• 年卷期：v.118,no.18(May 8, 2014)
• ISSN：1520-5215

文摘

We report a study on the temperature dependence of the valence electron excitation spectrum of CO₂ performed using nonresonant inelastic X-ray scattering spectroscopy. The excitation spectra were measured at the temperatures of 300 and 850 K with momentum-transfer values of 0.4鈥?.8 脜^鈥?, i.e., from the dipole limit to the higher-multipole regime, and were simulated using high-level coupled cluster calculations on the dipole and quadrupole level. The results demonstrate the emergence of dipole-forbidden excitations owing to temperature-induced bending mode activation and finite momentum transfer.