Multi-dimensional coherent spectroscopy

To study ultrafast electronic coherences in molecular crystals, as well as biological systems, we developed a setup for ultra-broadband two-dimensional Fourier transform spectroscopy. The output of a 6 – 10 kHz Ti:Sa femtosecond laser is broadened by self-phase modulation inside an argon filled hollow core fiber, to produce continuum (500 – 1000 nm) laser pulses that are compressed to sub-10 fs, using a set of chirped mirrors (Ultrafast Innovations). We use the compressed laser pulses to perform photon echo spectroscopy in a passively phase stabilized BOXCARS geometry. Three excitations pulses with time delays τ and T stimulate a third order non-linear signal (the photon echo) that is emitted after a third time delay t (shown in the figure) and heterodyne detected with a local oscillator field (not shown). Fourier transformation along τ and t yields two dimensional correlation spectra of the excitation and detection frequencies at a certain population time T, allowing us to extract information that are “hidden” in classical transient absorption spectroscopy.

 

Recent publications:
A. Al Haddad, A. Chauvet, J. Ojeda, C. Arrell and F. van Mourik et al. Set-up for broadband Fourier-transform multidimensional electronic spectroscopy, in Optics Letters, vol. 40, num. 3, p. 312-315, 2015.