Resonant and nonresonant surface-enhanced hyper-Raman spectroscopy with a picosecond laser. Effect of the excitation pulse width

We report resonant and nonresonant surface-enhanced hyper-Raman scattering (SEHRS) spectra of basic fuchsin and 3-hydroxykynurenine in the Ag colloid system with a picosecond pulse laser of high repetition rate (82 MHz). It is demonstrated that, at constant average power, fiber-optic compression of the 100 ps fundamental output of a Nd:YAG laser to ≈ 5 ps increases the intensities of surface-enhanced hyper-Raman scattering and second-harmonic generation by approximately one order of magnitude. We have thus obtained high-quality SEHRS spectra for both molecules with only 0.1 W laser excitation. These results are significant in the development of SEHRS as a useful spectroscopic technique.