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We present high-resolution (R~15000) VLT/UVES optical spectra of twoplanetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes havealready been found. These spectra are of high-quality (S/N > 300) for PN Tc 1,which permits us to search for the expected electronic transitions of neutralC60 and diffuse interstellar bands (DIBs). Surprisingly, we report thenon-detection of the most intense optical bands of C60 in Tc 1, although thiscould be explained by the low C60 column density estimated from the C60infrared bands if the C60 emission peaks far away from the central star. Thestrongest and most common DIBs in both fullerene PNe are normal for theirreddening. Interestingly, the very broad 4428 A DIB and the weaker 6309 A DIBare found to be unusually intense in Tc 1. We also report the detection of anew broad (FWHM~5 A) unidentified band at ~6525 A. We propose that the 4428 ADIB (probably also the 6309 A DIB and the new 6525 A band) may be related tothe presence of larger fullerenes (e.g., C80, C240, C320, and C540) andbuckyonions (multishell fullerenes such as C60@C240 and C60@C240@C540) in thecircumstellar envelope of Tc 1.

Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection