Development of a Multiplex Infrared-visible Sum-frequency Generation Spectrometer with Wavelength Tunability of the Visible Probe

摘要

We present a newly developed multiplex sum-frequency generation (SFG) spectrometer that has wavelength tunability of the visible probe. The tunable wavelength range of the visible probe was 470 approx 800, and 401 nm. The frequency width of the visible probe were 7 approx 10 cm~(-1). An SFG spectrum over a 400 cm~(-1) spectral region was obtainable by a single measurement. We measured SFG spectra of a self-assembled monolayer of octadecanethiol on a gold substrate with the visible probes laser of various wavelengths (401, 477, 535, 633 nm). The observed spectra were drastically changed with the wavelength of the visible probe. We ascribed this spectral change to the change in the phase and magnitude of the contribution from the gold substrate because the interband transition threshold of gold is located in the wavelength range of the visible probe.