1997A&A...327..337J

High spectral resolution studies of the two Diffuse Interstellar Bands (DIB) previously assigned to C60⁺ (λ9577 and λ9632) confirm that these DIBs have the same full-width-at-half-maximum and behave similarly in dense cloud environments where the DIBs are weakened relative to the diffuse interstellar medium. Their relative strength, however, is less than previously reported and differs from the relative intensities measured from matrix isolation spectroscopy. A simultaneous search for the two laboratory derived vibronic tranistions of C60⁺ at about 9366 and 9419 Å has not lead to the detection of the two weak counterparts stronger than 15% of λ9577. We conclude that for the diffuse band spectrum to be consistent with C60⁺, not only the measured band positions have to be slightly different in the gas-phase, but also the relative intensity of the two main lines has to differ significantly from that of the known laboratory data.