The ability to attenuate the LO is particularly beneficial when working with weak IR probes, such as thiocyanate or nitrile vibrational modes ; On the other hand, the pump-probe geometry has two important advantages. First, the straightforward two-beam geometry streamlines the alignment process. Second, this geometry can be implemented using a pulse shaper which provides several advantages including fast data acquisition and scatter suppression by phase cycling . In addition, precise control of the pulse pairs removes the need to phase spectra. However, the lack of sensitivity in the pump-probe geometry can be limiting, and indeed, chromophores with large oscillator strength are often used within this geometry. Recently, significant efforts have dedicated to improving the sensitivity of the pump-probe geometry, aiming for a background-free data collection with a pulse shaper . Xiong and Zanni adopted a polarization grating configuration in the pump-probe setup to increase the signal strength and eliminate unwanted background noise . Jonas and coworkers introduced a Sagnac interferometer in partially collinear 2D electronic spectroscopy (2D ES) in order to measure a nearly background-free signal in the pump-probe geometry .