Strong-field- versus weak-field-ionization pump-probe spectroscopy

Spectroscopic and Structural Probing of Excited-State Molecular Dynamics with Time-Resolved Photoelectron Spectroscopy and Ultrafast Electron Diffraction

“…1 into three bands and plotted them as a function of C-I bond distance. The wave packet associated with the direct dissociation trajectories moves out to large C-I distances rapidly after internal conversion from the initially photoexcited states (13)(14)(15)(16)(17) to the dissociative states (9-12), while the wave packet associated with the indirect trajectories remains bound in states 13-17 for about 200 fs and then eventually internally converts, followed by dissociation. Panels (b1) and (b2) show the electronic state index as well as the potential energy as a function of delay time after the UV pump pulse.…”

“…Timedependent calculations have evolved to produce very detailed pictures of molecular dynamics, but they require many approximations and thus must be benchmarked against measurements in order to ensure accuracy and relevance. It is important that these simulations can be directly compared (without adjustable parameters) to time-resolved experimental data, as has been done, e.g., with quantum dynamics simulations [8][9][10][11][12], trajectory surface hopping calculations [13][14][15], ab initio multiple spawning (AIMS) [16][17][18][19][20][21], and many more approaches. While a given observable may apply certain constraints to a calculation, many ambiguities will remain.…”

Ultrafast and radiationless electronic excited state decay of uracil and thymine cations: computing the effects of dynamic electron correlation

“…strong UV-C) required to remove electrons from the nucleobases (although this is reduced upon N1 substitution when moving to nucleosides and nucleotides, the nucleobase derivatives actually present in the DNA double helix chain). [6][7][8][9] This has for many years prevented in-depth studies, but recent developments in the generation of high-energy few-cycle UV-C pulses 10,11 and the advent of highenergy free electron laser sources 12 have opened up the possibility of studying time-resolved photoionisation processes in such small organic compounds and their use in pump-probe set-ups to monitor photo-reactions.…”

Computing the Ultrafast and Radiationless Electronic Excited State Decay of Cytosine and 5‐methyl‐cytosine Cations: Uncovering the Role of Dynamic Electron Correlation

“…The ionisation of cytosine derivatives has been a topic of scarce study in the literature, with the only references found by us being relative to the specific UV/Vis absorption spectral fingerprints of cytosine +[22] as well as their IR features . Very little is also known about the cationic excited state decay relaxation, particularly comparing to other similar systems like the RNA nucleobase uracil . The only works available in the literature are characterisation of the Dyson norms of cytosine and the evolution of the cationic manifold along the relaxation of the bright and initially accessed singlet decay channel by Matsika and co‐workers, which cover different facets of potential ionisation mechanisms while not depicting the actual cation generation and its excited state decay relaxation channels.…”