Computational IR spectroscopy for detecting the endohedral complexes M@C60 (M = Li, Na, K) in stellar and interstellar environments Seyedsaeid Ahmadvand, Sergey A. Varganov* Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia Street, Reno, NV 89557-0216, United States. *E-mail: svarganov@unr.edu Abstract Infrared (IR) spectroscopy is a very powerful technique for detecting new molecules in interstellar space. Recently, fullerenes C60 and C70 were discovered in the young planetary nebula Tc 1 (Cami et al. Science 2010, 329, 1180) using astronomical and computational IR spectra. This discovery has lead to increased interest in search of new fullerene derivatives, such as the endohedral complexes with alkali metals (M@C60, M=Li, Na, K), in stellar and interstellar environments. Obtaining the high-quality IR spectra of the M@C60 complexes is essential for the identification of these endohedral complexes in space. The experimental spectra are hard to obtain due to the difficulties associated with purification of the endohedral complexes. We performed the density functional theory (DFT) calculations to obtain harmonic IR spectra for different isomers of M@C60. The insertion of an alkali metal atom inside C60 results in symmetry reduction and splitting of the peaks in the fullerene’s IR spectra. To study the low-frequency anharmonic modes of the metal atoms inside the fullerene cage, vibrational self-consistent field theory in combination with DFT and semi-empirical methods was used. The modeled IR spectra of the M@C60 complexes include anharmonic corrections to harmonic frequencies, overtones and combination bands. The obtained computational IR spectra can be used to identify the signatures of endohedral fullerenes in space.

Computational IR spectroscopy for detecting the endohedral complexes M@C60 (M = Li, Na, K) in stellar and interstellar environments

251st National Meeting (2016)

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