An Evaluation of Maximum Determination Methods for Center Line Slope Analysis

Abstract

Ultrafast molecular dynamics are frequently extracted from two-dimensional (2D) spectra via the center line slope (CLS) method. The CLS method depends on the accurate determination of frequencies where the 2D signal is at a maximum, and multiple approaches exist for the determination of that maximum. Various versions of peak fitting for CLS analyses have been utilized; however, the impact of peak fitting on the accuracy and precision of the CLS method has not been reported in detail. Here, we evaluate several versions of CLS analyses using both simulated and experimental 2D spectra. The CLS method was found to be significantly more robust when fits were used to extract the maxima, particularly fitting methods that utilize pairs of opposite-sign peaks. However, we also observed that pairs of opposite-signed peaks required more assumptions than single peaks, which are important to check when interpreting experimental spectra using peak pairs.

Artificial-Intelligence-Enhanced On-the-Fly Simulation of Nonlinear Time-Resolved Spectra

“…As is becoming increasingly common in such situations, machine learning (ML) tools developed for artificial intelligence (AI) research can be applied to overcome the cost limitations . Successful examples in the related fields include creating surrogate ML models for excited-state properties, , which can be used to increase the precision of linear absorption spectra , and uncertainty quantification, predict two-photon absorption cross sections, and perform non-adiabatic molecular dynamics of molecular systems. − Beyond linear spectra, ML methods were also successfully used in the interpretation of nonlinear spectroscopic signals, i.e., for the reconstruction of certain facets of system dynamics from experimental transient absorption pump–probe , and 2D electronic spectra − as well as “denoising” experimental signals . A few studies invoked ML for the evaluation of nonlinear signals, i.e., predicting 2D electronic spectra of proteins , and extracting relevant parameters, such as orientations of transition dipole moments, from these spectra .…”