[en] Highlights: • Polyynes were synthesized by femtosecond laser ablation of SWCNTs in methanol. • SERS spectra of isolated polyynes in Ag colloid were investigated. • Clear peaks in the region of β band of C₈H₂ were observed in the damp-dried colloid. Polyyne samples C_2nH₂ (n = 4–6) were synthesized by irradiating single-wall carbon nanotubes in methanol with intense femtosecond laser pulses. For obtaining isolated polyynes (C₈H₂, C₁₀H₂, and C₁₂H₂), the original solution was separated by high performance liquid chromatography. The surface-enhanced Raman scattering spectra of isolated polyynes in Ag colloid have been investigated with naturally drying time, and clear peaks in the region of β band for the isolated C₈H₂ were observed at 1910 and 1958 cm⁻¹ in the damp-dried Ag colloid samples for the first time.