Resolving High Order Tensor Interactions in C₆₀ Fullerenes

Lee R. Liu, Dina Rosenberg, P. Bryan Changala, David J. Nesbitt, Timur Tscherbul, Jun Ye

We present an experimental rovibrational spectrum of gas phase C₆₀ fullerene, obtained by QCL (Qunatum Cascade Laser) cavity enhanced absorption spectroscopy. The highly symmetrical icosahedral structure of C₆₀ enables the observation of individual rovibrational transitions.

In the first work on C₆₀ from our group [1], the rovibrational spectrum showed a striking difference between the R branch (rotational transitions that result from rotational excitation) and the P branch (transitions resulting from rotational relaxation). While the first obeyed a semi rigid-rotor structure throughout the spectrum (up to J~330), the latter demonstrated a splitting pattern, where single transitions were seemingly separated to low intensity, congested absorption lines. Comprehensive analysis of this P branch spectrum strongly suggests that these splitting patterns result from intramolecular vibrational interactions via the rotational rank 6 and rank 10 tensors. The high precision and very high SNR in this experiment have provided a uniquely detailed spectrum, and consequently better comprehension of the complexities in C₆₀.

[1] P. B. Changala, M. L. Weichman, K. F. Lee, M. E. Fermann, and J. Ye, Science (1979) 363, 49 (2019).