The C-2 d(3)II(g)-a(3)II(u) (v' - v") Swan band emission spectrum induced by the laser ablation of graphite in the superfluid helium around 1.5 K, was observed. Only the vibrational progression of Deltav = v' - v", where Deltav less than 0 are observed, indicating fast (tau < 100ns) vibrational relaxation in superfluid helium. This result also indicates a unique characteristic of superfluid helium as a circumstance of chemical processes.