Near-infrared excitation of alkane ultra-violet fluorescence

We report the generation of ultra-violet fluorescence from linear and cyclic saturated hydrocarbons in neat solution when excited with femtosecond near-infrared laser pulses at 800 nm. Fluorescence decay, spectra and power dependence studies are reported. Steady-state and time-resolved experiments are in agreement with previously reported data obtained with one-photon vacuum ultra-violet, X-ray, electron impact and two-photon excitation. Our results indicate that the mechanisms leading to the fluorescing excited state are multi-photon absorption and ionisation with the latter followed by diffusion-controlled geminate cation–electron recombination.