Resonant Third-Order Susceptibility of PbSe Quantum Dots Determined by Standard Dilution and Transient Grating Spectroscopy

We present a methodology for obtaining quantitative ultrafast multiresonant coherent multidimensional spectra. Using the solvent and cuvette as an internal standard, we extract the quantitative third-order susceptibility of PbSe quantum dots through a method of standard dilution. The resonant susceptibility is extracted using a few parameter fit. After accounting for differences in pulse width and experimental geometry, we find agreement between our measured susceptibility and prior measurements. We demonstrate how the measured susceptibility can be directly compared with theoretical models of non-linearity (state-filling). Our internal standard methodology should be generally applicable to nonlinear spectroscopy.