Fig. 3: Delay-time dependence.
a Intensity-corrected spectra from PNA solution with various Δt from −1.3 to +1.3 ps. b Delay-time dependence of the non-resonant background signals corresponding to the cross-correlation of the ω1 and ω2 pulses at 4ω1−ω2. The FWHM was determined to be 1.3 ps.
