Comparison between the normalized Spitzer/IRS spectrum of three YSOs (EC92, IRAS03235+3004, and L1455 IRS3) and laboratory spectra of CH₃CN ice. Top panels: the CH₃CN and CH₃CN:H₂O ice spectra at 15 K are plotted with the YSO spectra (the continuum, and contributions from H₂O, and silicate features are subtracted). The 6.90, 7.09, 7.27, 9.60 µm features of CH₃CN are marked with a vertical dashed line. Bottom panels: Spitzer/IRS spectrum of EC92, IRAS03235+3004, and L1455 IRS3 (from left to right) in the 8.5–10 region. In addition, the laboratory spectrum of pure CH₃CN ice at 15 K (blue) is shown. In the bottom panels, the spectrum of CH₃CN is scaled to the observations using the 9.60 µm band of methyl cyanide.