Structures and Dipole Moments of Molecules in Their Electronically Excited States

Exploring Bethe–Salpeter Excited-State Dipoles: The Challenging Case of Increasingly Long Push–Pull Oligomers

“…Experimentally, μ ES values are indirectly accessed either through Stark effect measurements or solvatofluorochromism determinations. In the former, one measures the variations of the position and topologies of the vibronic signatures under an external electric field, and such an approach can be applied to very small compounds in gas phase only and remains far from error-free. − In the solvatofluorochromic approach, one studies the changes of the position of the fluorescence maximum in solvent of various polarities and deduce μ ES using the Lippert–Mataga equation, an approach that comes with significant simplifications and a rather large incertitude . This is why most μ ES values are theoretically determined.…”

Comprehensive study of the pentad bending triad region of germane: Positions, strengths, widths and shifts of lines in the 2ν2, ν2+Ulenikov1, Gromova2, Bekhtereva3 et al. 2021Journal of Quantitative Spectroscopy and Radiative Transfer6000View full textAdd to dashboardCite

“…on the functions |A and |B of the lower and upper ro-vibrational states. The value P Z is the Z−component of the dipole moment of a molecule (see, e.g., [53], [54])…”

Mountaineering Strategy to Excited States: Highly Accurate Oscillator Strengths and Dipole Moments of Small Molecules

“…48,49 The measurements of ES dipoles are also cumbersome. 50 The typical strategy is to investigate solvatofluorochromism, that is, to measure the shift of the emission wavelength in a series of solvents of various polarities, and to fit the results with the Lippert−Mataga equation within an Onsager-like interaction model. Such an approach is obviously not a direct gas-phase measurement and comes with significant assumptions, making the final error often too large to allow benchmarking.…”

“…As nicely summarized elsewhere, the former typically requires extrapolations of the cross-sections measured at various momenta/angles (such extrapolations are not error-free), whereas the latter can be plagued by saturation and interaction effects (yielding to underestimation of the actual f value). In any case, the so-called “electronic” or “optical” f , which is of interest here, is not directly measurable, and postprocessing of the experimental raw data (lifetimes or cross sections) is needed to access its “experimental” value. , The measurements of ES dipoles are also cumbersome . The typical strategy is to investigate solvatofluorochromism, that is, to measure the shift of the emission wavelength in a series of solvents of various polarities, and to fit the results with the Lippert–Mataga equation within an Onsager-like interaction model.…”

“…Such an approach is obviously not a direct gas-phase measurement and comes with significant assumptions, making the final error often too large to allow benchmarking . Alternatively, one can also measure μ ES directly in gas phase by studying how external electric fields tune the position and shape of the vibronic peaks (the so-called Stark effect). , Only the latter approach can be considered as sufficiently robust for reference purposes. Still, such Stark effect measurements do typically provide an “adiabatic” version of μ ES , that is, the ES dipole measured at the ES equilibrium geometry.…”