Absorption spectra of the pyridine-Th@Au₁₄ complex at three different adsorption sites. The three different colored lines (1, 2, 3) denote three coordination types of the gold atoms (iso1, iso2, and iso3), serving as prospective adsorption sites for pyridine molecules in unit SERS study. Absorption coefficients are given as the oscillator strength in unit a.u. and wavelength in nm. Spectra were broadened by Lorentzian function with a width of 15 cm⁻¹. Adapted with permission from Ref. [8]. Copyright 2016 Springer.