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arXiv · 2609.27027

Coherent Multidimensional Spectroscopy at the Few-Cycle Limit: Accounting for the Pump Spectrum

Jacob S. Higgins·Gerrit N. Christenson·James D. Gaynor
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Abstract

Coherent multidimensional spectroscopy will benefit greatly from near single-cycle pulses through the spectral breadth of states that can be accessed and the high frequency oscillations that can be resolved. However, the necessary cost of working with such pulses is the spectral structure arising from efficient self-phase modulation, which imparts into the signal and complicates interpretation of the molecular response. In this paper, we develop an in-operando approach to characterize and remove pump spectral features from two-dimensional spectroscopic signals. The pump spectrum is retrieved via an interferometric integrated autocorrelation measurement that runs concurrently with the experiment and thereby inherits the same time and frequency domain properties. A deconvolution procedure then suppresses noise and extracts the third-order response from the total signal. The analysis enables correction of spectral intensities and unambiguous assignment of spectral features to the molecular response. This work pushes multidimensional spectroscopy toward the impulsive limit and enables integration with other nonlinear spectroscopies such as attosecond spectroscopy - all without compromising few-cycle pulse properties.

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Jacob S. Higgins, Gerrit N. Christenson, James D. Gaynor. 2026-09-22. Coherent Multidimensional Spectroscopy at the Few-Cycle Limit: Accounting for the Pump Spectrum. https://arxiv.org/abs/2609.27027

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