UV–Vis emission spectra of shock-processed C₆₀ showing C₂ features and a broad continuum. The spectra were recorded under different experimental conditions, as reported in Table 1. The C₂ vibronic bands were labeled according to the Herzberg (1995) notation: Δυ = υ′−υ″; υ′ and υ″ refer to the upper and lower vibrational levels, respectively. The spectral features below 420 nm flagged with an asterisk (*) were assigned to contaminants.