Two-dimensional spectroscopy for non-specialists

Unravelling the Photoprotective Mechanisms of Nature-Inspired Ultraviolet Filters Using Ultrafast Spectroscopy

“…It is particularly useful in systems with multiple interacting components for tracking excited-state energy transfer processes. Likewise, it allows one to extract the species responsible for an absorption or emission signal observed in the excited state [ 142 , 143 ]. This information is often difficult to observe by probing the electronic state using TEAS.…”

Quantifying non-Markovianity in underdamped versus overdamped environments and its effect on spectral lineshape

“…Whilst the population time is less than the correlation time, T < τ c , the inhomogeneous distribution of system-bath interactions within the ensemble contributes a series of Lorentzian peaks along the diagonal, which produce the elongated Gaussian shape when summed. 7,8 As the population time increases, system-bath correlations are lost as the correlation function decays, decreasing this inhomogeneous broadening and leaving a more rounded peak dominated by the homogeneous lineshape. 38,47,48 The decay in the correlation function is directly related to the decrease in ellipticity, E, of the peaks in the 2D spectra, which compares the width of a Gaussian fitted to the diagonal of the peak, ς D , with that of the antidiagonal, ς A , [49][50][51] Figure 6 shows that the ellipticity of the three overdamped baths follows an exponential decay with population time and that the slower decay for inhomogeneous baths is accompanied by increasing N .…”

“…6 Two-dimensional (2D) spectroscopy overcomes this by separating the inhomogeneous and homogeneous contributions with the use of a four-wave mixing procedure; the inhomogeneous component being projected onto the diagonal axis and the homogeneous onto the anti-diagonal. 3,7,8 The two-dimensional lineshape depends sensitively on the time scale of interactions of the chromophore probed with the environment. Homogenenous and inhomogeneous broadening are the short and long time limits, respectively, but, if the system-bath interaction time scale is not in either limit, the spectral lineshape will be sensitive to the time scale.…”

iSPECTRON: A simulation interface for linear and nonlinear spectra with ab‐initio quantum chemistry software

“…The past few decades have witnessed the birth of multi-dimensional multi-pulse techniques, which allow one to study elementary molecular events such as energy and charge transfer processes, formation and evolution of vibrational and electronic coherences, conformational and solvent dynamics and even to study the evolution of a system simultaneously in time and space (4D spectroscopy). [1][2][3][4][5][6][7][8] In combination with ultra-short laser pulses with high phase stability, these novel techniques have equipped researchers with the necessary tools to unravel gas-and condensed-phase dynamics in the sub-femtosecond (fs, 10 −15 s) and even in the attosecond (as, i.e., 10 −18 s) 9,10 regimes with an unprecedented level of detail. Nonetheless, connecting the optical response of the system to the underlying quantum-chemical structure and vibronic…”