Internal Conversion versus Intersystem Crossing: What Drives the Gas Phase Dynamics of Cyclic α,β-Enones?

Schalk, Oliver; Schuurman, Michael S.; Wu, Guorong; Lang, Peter; Mucke, Melanie; Feifel, Raimund; Stolow, Albert

doi:10.1021/jp4124937

Cited by 47 publications

(59 citation statements)

References 45 publications

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“…This broadening is structureless and monotonously increasing from higher to lower electron kinetic energies. This is another indicator that the lower lying states are accessed later in the ionization process 70 and agrees with the lengthening of the time constants of (22 ± 5) fs. No dependence from ionization through Rydberg states was observed.…”

Section: B Time-resolved Photoelectron Spectroscopysupporting

confidence: 81%

“…Along the reaction coordinate, the character of the excited states changes, which was observed in earlier studies of CHD 30,73 but is also known from other small dienes that exhibit large amplitude motions such as butadiene 72 or CPD. 47,70 Many earlier investigations considered two excited states in the reaction path of CHD, influenced by the early work of van der Lugt and Oosterhoff. 5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 Finally, we compare our theoretical results with previous investigations.…”

Section: Comparison With Literaturementioning

confidence: 99%

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Cyclohexadiene Revisited: A Time-Resolved Photoelectron Spectroscopy and ab Initio Study

et al. 2016

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We have reinvestigated the excited state dynamics of cyclohexa-1,3-diene (CHD) with time-resolved photoelectron spectroscopy and fewest switches surface hopping molecular dynamics based on linear response time-dependent density functional theory after excitation to the lowest lying ππ* (1B) state. The combination of both theory and experiment revealed several new results: First, the dynamics progress on one single excited state surface. After an incubation time of 35 ± 10 fs on the excited state, the dynamics proceed to the ground state in an additional 60 ± 10 fs, either via a conrotatory ring-opening to hexatriene or back to the CHD ground state. Moreover, ring-opening predominantly occurs when the wavepacket crosses the region of strong nonadiabatic coupling with a positive velocity in the bond alternation coordinate. After 100 fs, trajectories remaining in the excited state must return to the CHD ground state. This extra time delay induces a revival of the photoelectron signal and is an experimental confirmation of the previously formulated model of two parallel reaction channels with distinct time constants. Finally, our simulations suggest that after the initially formed cis-Z-cis HT rotamer the trans-Z-trans isomer is formed, before the thermodynamical equilibrium of three possible rotamers is reached after 1 ps.

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Section: B Time-resolved Photoelectron Spectroscopysupporting

confidence: 81%

Section: Comparison With Literaturementioning

confidence: 99%

Cyclohexadiene Revisited: A Time-Resolved Photoelectron Spectroscopy and ab Initio Study

et al. 2016

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“…Such a delay was earlier quantified by optimizing time-zero (t 0 ) as an additional parameter in a global 2D fitting routine of the experimental photoelectron spectra. 12,17,55 This was found to…”

Section: Experimental Trpesmentioning

confidence: 89%

Hexamethylcyclopentadiene: time-resolved photoelectron spectroscopy and ab initio multiple spawning simulations

Wolf

Kuhlman

Schalk

et al. 2014

Phys. Chem. Chem. Phys.

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“…57 In the first case, they reported ISC from the mixed 1 B 1 / 1 A 2 states to the 3 B 2 state on time scales of 750−150 fs, depending on the excitation energy. These were rationalized by Gonzalez and co-workers 58 using ab initio-based dynamics simulations.…”

Section: Ultrafast Iscmentioning

confidence: 98%

Ultrafast Photophysics of Transition Metal Complexes

2015

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The properties of transition metal complexes are interesting not only for their potential applications in solar energy conversion, OLEDs, molecular electronics, biology, photochemistry, etc. but also for their fascinating photophysical properties that call for a rethinking of fundamental concepts. With the advent of ultrafast spectroscopy over 25 years ago and, more particularly, with improvements in the past 10-15 years, a new area of study was opened that has led to insightful observations of the intramolecular relaxation processes such as internal conversion (IC), intersystem crossing (ISC), and intramolecular vibrational redistribution (IVR). Indeed, ultrafast optical spectroscopic tools, such as fluorescence up-conversion, show that in many cases, intramolecular relaxation processes can be extremely fast and even shorter than time scales of vibrations. In addition, more and more examples are appearing showing that ultrafast ISC rates do not scale with the magnitude of the metal spin-orbit coupling constant, that is, that there is no heavy-atom effect on ultrafast time scales. It appears that the structural dynamics of the system and the density of states play a crucial role therein. While optical spectroscopy delivers an insightful picture of electronic relaxation processes involving valence orbitals, the photophysics of metal complexes involves excitations that may be centered on the metal (called metal-centered or MC) or the ligand (called ligand-centered or LC) or involve a transition from one to the other or vice versa (called MLCT or LMCT). These excitations call for an element-specific probe of the photophysics, which is achieved by X-ray absorption spectroscopy. In this case, transitions from core orbitals to valence orbitals or higher allow probing the electronic structure changes induced by the optical excitation of the valence orbitals, while also delivering information about the geometrical rearrangement of the neighbor atoms around the atom of interest. With the emergence of new instruments such as X-ray free electron lasers (XFELs), it is now possible to perform ultrafast laser pump/X-ray emission probe experiments. In this case, one probes the density of occupied states. These core-level spectroscopies and other emerging ones, such as photoelectron spectroscopy of solutions, are delivering a hitherto unseen degree of detail into the photophysics of metal-based molecular complexes. In this Account, we will give examples of applications of the various methods listed above to address specific photophysical processes.

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Internal Conversion versus Intersystem Crossing: What Drives the Gas Phase Dynamics of Cyclic α,β-Enones?

Cited by 47 publications

References 45 publications

Cyclohexadiene Revisited: A Time-Resolved Photoelectron Spectroscopy and ab Initio Study

Cyclohexadiene Revisited: A Time-Resolved Photoelectron Spectroscopy and ab Initio Study

Hexamethylcyclopentadiene: time-resolved photoelectron spectroscopy and ab initio multiple spawning simulations

Ultrafast Photophysics of Transition Metal Complexes

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