Data analysis in transient electronic spectroscopy – an experimentalist's view

Abstract

Time-resolved electronic spectroscopy has grown into a technique that provides hundreds to thousands of electronic spectra with femtosecond time resolution. This enables complex questions to be interrogated, with an obvious cost that the data are more detailed and thus require accurate modelling to be properly reproduced. Data analysis of these data comes in a variety of forms, starting with a variety of assumptions about how the data may be decomposed. Here, four different types of analysis commonly used are discussed: band-shape analysis, global kinetic analysis, lifetime distribution models, and soft-modelling. This review provides a 'user's guide' to these various methods of data analysis, and attempts to elucidate their successes, domains in which they may be useful, and potential pitfalls in their usage.

URSA-PQ: A Mobile and Flexible Pump-Probe Instrument for Gas Phase Samples at the FLASH Free Electron Laser

“…This observable as a function of relative delay between UV-pump and X-ray-probe pulse is shown by the blue dots in Figure 5b, together with a theoretical fit shown by the orange line. The fit function includes a Gaussian describing the time-resolution, convoluted with two exponential decays (see for instance Equation (3) in Reference [34]). The second exponential decay is longer than 100 ps and has limited influence on the data in the delay window shown.…”

Ultrafast Photoconversion Dynamics of the Knotless Phytochrome SynCph2

“…Our global target analysis (for details see Material and Methods or [ 52 , 57 , 58 ]) of the IR TA data using a sequential model resulted in four kinetic components ( Figure 3 C). The first lifetime component (300 fs) is at the limit of our experimental time resolution, and while straightforward assignment is hard, it is plausibly related to early dynamics on the excited state potential energy surface as indicated by the vis TA data (see above).…”

“…Based on the qualitative insight provided by the LDA of the vis data, we constructed kinetic models and fitted those directly to the experimental data to obtain quantitative information (kinetic rates for the different transition steps and the spectra of the involved species) on the P fr kinetics (see refs [ 52 , 57 , 58 ] for details on global target analysis and the Methods section for specific technical details). The P fr LDM ( Figure 5 B) clearly shows only one lifetime distribution (at about 300–400 fs) accounting for the decay of the relaxed excited state.…”

Understanding the Photoexcitation of Room Temperature Ionic Liquids

“…The subsequent probing of photo‐induced events are performed by various techniques, e. g. broadband absorption spectroscopy or in general, nonlinear optical spectroscopy such as optical heterodyne detected optical Kerr effect (OHD‐OKE) measurements, fluorescence up‐conversion, two‐dimensional IR detection and fs coherent anti‐Raman scattering (fs‐CARS), electron paramagnetic resonance (EPR), dielectric spectroscopy and some more that are mentioned in the due course of this review. The following data analysis plays also a major role and is therefore worth mentioning [16] . Theoretical calculations are often based on density functional theory (DFT) [17] and molecular‐dynamics (MD) simulations [18]…”