Substituent Effects on Dynamics at Conical Intersections: Cyclopentadienes

Schalk, Oliver; Boguslavskiy, Andrey E.; Stolow, Albert

doi:10.1021/jp911286s

Cited by 75 publications

(109 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Time constants and their decay associated spectra (DAS) were determined by a Levenberg−Marquart 2D global fitting routine, as explained in detail in ref 41. In brief: The time-and energy-resolved photoelectron signal S(E,Δt) can be described as a sum of i kinetic steps through…”

Section: Resultsmentioning

confidence: 99%

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

Schalk

Schuurman

et al. 2014

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=36f80283-c080-4d5b-b6d4-7f3021ca6cf9 http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=36f80283-c080-4d5b-b6d4-7f3021ca6cf9 ABSTRACT: We investigate the competition between intersystem crossing (ISC) and internal conversion (IC) as nonradiative relaxation pathways in cyclic α,β-unsaturated enones following excitation to their lowest lying 1 ππ* state, by means of time-resolved photoelectron spectroscopy and ab initio computation. Upon excitation, the 1 ππ* state of 2-cyclopentenone decays to the lowest lying 1 nπ* state within 120 ± 20 fs. Within 1.2 ± 0.2 ps, the molecule subsequently decays to the triplet manifold and the singlet ground state, with quantum yields of 0.35 and 0.65, respectively. The corresponding dynamics in modified derivatives, obtained by selective methylation, show a decrease in both IC and ISC rates, with the quantum yields of ISC varying between 0.35 and 0.08. The rapid rates of ISC are explained by a large spin orbit coupling of 45−60 cm −1 over an extended region of near degeneracy between the singlet and triplet state. Furthermore, the rate of IC is depressed by the existence of a well-defined minimum on the 1 nπ* potential energy surface. The nonadiabatic pathways evinced by the present results highlight the fact that these molecular systems conceptually represent "intermediate cases" between ultrafast dynamics mediated by vibrational motions at conical intersections versus those by statistical decay mechanisms.

show abstract

Section: Resultsmentioning

confidence: 99%

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

Schalk

Schuurman

et al. 2014

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

show abstract

“…For details, see ref 42. Panels d−f of Figure 6 show the time dependence of the photoelectron yield in the range of 1.0−1.2 eV, excited at 370, 350, and 330 nm, respectively.…”

Section: Resultsmentioning

confidence: 99%

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Sekikawa

Schalk

et al. 2013

J. Phys. Chem. A

Self Cite

View full text Add to dashboard Cite

Excited-state intramolecular proton transfer (ESIPT) in salicylideneaniline (SA) and selected derivatives substituted in the para position of the anilino group have been investigated by femtosecond time-resolved photoelectron spectroscopy (TRPES) and time-dependent density functional theory (TDDFT). SA has a twisted structure at the energetic minimum of the ground state, but ESIPT is assumed to take place through a planar structure, although this has not been fully established. The TRPES studies revealed that the excited-state dynamics within the S 1 band varied significantly with excitation wavelength. At finite temperatures, the ground state was found to sample a broad range of torsional angles, from planar to twisted. At lower photon energies (370 nm), only the planar groundstate molecules were excited, and the excited-state reaction took place within 50 fs. At higher energies (350 and 330 nm), predominantly twisted ground-state molecules were excited: they had to planarize before ESIPT could occur. This process was found to be slower in methylated SA but did not change significantly in the brominated and nitrated SAs. These substitution effects on the decay dynamics can be explained by modifications of the potential barriers, as predicted by the TDDFT calculations, and support the mechanism of a twisting motion of the anilino ring prior to ESIPT. The contribution of another pathway leading to internal conversion within the enol form was found to be minor at the excitation wavelengths considered here.

show abstract

“…Time constants characterizing the evolution of the photoelectron spectra were determined by a LevenbergÀMarquart global fitting routine, as described in ref 48. A short summary of the method as well as a detailed analysis of the fitting procedure are given in the Supporting Information, while the extracted time constants are given in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Through-Bond Interactions and the Localization of Excited-State Dynamics

et al. 2011

Self Cite

View full text Add to dashboard Cite

The influence of through-bond interactions on nonadiabatic excited-state dynamics is investigated by time-resolved photoelectron spectroscopy (TRPES) and ab initio computation. We compare the dynamics of cyclohexa-1,4-diene, which exhibits a through-bond interaction known as homoconjugation (the electronic correlation between nonconjugated double bonds), with the nonconjugated cyclohexene. Each molecule was initially excited to a 3s Rydberg state using a 200 nm femtosecond pump pulse. The TRPES spectra of these molecules display similar structure and time constants on a subpicosecond time scale. Our ab initio calculations show that similar sets of conical intersections (a [1,2]- and [1,3]-hydrogen shift, as well as carbon–carbon bond cleavage) are energetically accessible to both molecules and that the geometry and orbital composition at the minimum energy crossing points to the ground state are directly analogous. These experimental and computational results suggest that the excited-state dynamics of cyclohexa-1,4-diene become localized at a single double bond and that the effects of through-bond interaction, dominant in the absorption spectrum, are absent in the excited-state dynamics. The notion of excited-state dynamics being localized at specific sites within the nuclear framework is analogous to the localization of light absorption by a subsystem within the molecule, designated a chromophore. We propose the utility of the analogous concept, denoted here as a dynamophore.

show abstract

Substituent Effects on Dynamics at Conical Intersections: Cyclopentadienes

Cited by 75 publications

References 38 publications

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

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

Initial Processes of Proton Transfer in Salicylideneaniline Studied by Time-Resolved Photoelectron Spectroscopy

Through-Bond Interactions and the Localization of Excited-State Dynamics

Contact Info

Product

Resources

About