Supporting Online Material for Real-time Vibrational Dynamics in Chlorophyll a Studied with a Few-Cycle

Supplementary Fig. S1 shows the schematic experimental set-up. We used a noncollinear optical parametric amplifier (NOPA) [1]–[3] as a light source for the pump–probe experiment [4]–[6]. The laser source of this system was a commercial regenerative amplifier (Spitfire; Spectra Physics). Its central wavelength, pulse duration, repetition rate and average output power were 790 nm, 50 fs, 5 kHz and 800mW, respectively. A small fraction of the fundamental was focused on a 1-mm thick sapphire plate to generate white light continuum seed. The main part of the fundamental was used to generate the second harmonic (SH) in a 0.17mm thick BBO (type I), which acted as the pump source of the NOPA after separated from the fundamental. The amplified signal pulse after the double-pass NOPA was first compressed by a pair of chirped mirrors and then a prism pair, resulting in a nearly Fourier transform (FT)-limited 6.8fs pulse with a spectrum extending from 539nm to 738nm, as shown in the inset to Fig. 1.