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Interconnection between Polarization-Detected and Population-Detected Signals: Theoretical Results and Ab Initio Simulations.
- Source :
-
Journal of chemical theory and computation [J Chem Theory Comput] 2024 Sep 10; Vol. 20 (17), pp. 7560-7573. Date of Electronic Publication: 2024 Aug 26. - Publication Year :
- 2024
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Abstract
- Most of spectroscopic signals are specified by the nonlinear laser-induced polarization. In recent years, population-detection of signals becomes a trend in femtosecond spectroscopy. Polarization-detected (PD) and population-detected signals are fundamentally different, because they are determined by photoinduced processes acting on disparate time scales. In this work, we consider the fluorescence-detected (FD) N -wave-mixing ( N WM) signal as a representative example of population-detected signals, derive a rigorous expression for this signal, and discuss its approximate variants suitable for numerical simulations. This leads us to the definition of the phenomenological FD (PFD) signal, which contains as a special case all definitions of FD signals available in the literature. Then we formulate and prove the population-polarization equivalence (PPE) theorem, which states that PFD N WM signals produced by (possibly strong) laser pulses can be evaluated as conventional PD signals in which the effective polarization is determined by the PFD transition dipole moment operator. We use the PPE theorem for the construction of the ab initio protocol for the simulation of PFD 4WM signals. As an example, we calculate electronic two-dimensional (2D) PFD spectra of the gas-phase pyrazine and compare them with the corresponding PD 2D spectra.
Details
- Language :
- English
- ISSN :
- 1549-9626
- Volume :
- 20
- Issue :
- 17
- Database :
- MEDLINE
- Journal :
- Journal of chemical theory and computation
- Publication Type :
- Academic Journal
- Accession number :
- 39185737
- Full Text :
- https://doi.org/10.1021/acs.jctc.4c00592