Drop-in two-dimensional electronic spectroscopy based on dual modulation in the pump-probe geometry

We report a compact design of two-dimensional electronic spectrometer (2DES) which can be built from any femtosecond broadband transient absorption setup using only a few optical elements and dual beam modulation by a single chopper blade. The dual pulse modulation design provides automatic extraction of the third order response as well as effective scatter suppression. Self-phasing of the 2D absorptive spectra is enabled directly by the pump-probe geometry. This passively stabilized instrument achieves interferometric phase stability of λ∕300 at 800 nm. The laser dye IR140 was used as a model chromophore to demonstrate the function of the instrument. Two ground state conformers of IR140 are observed in the 2D spectra. The presented simple modification of standard transient absorption spectrometer grants a wider access to a next generation research tool with advantages of low cost, simple operation, and data extraction. Our report presents an alternative solution of bringing the ultrafast research in chemistry, biology, and physics to the forefront of modern science.