Interacting Rydberg and valence states in radicals and molecules: experimental and theoretical studies

Reisler, H.; Krylov, Anna I.

doi:10.1080/01442350902989170

Cited by 107 publications

(129 citation statements)

References 168 publications

(254 reference statements)

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“…Reisler and Krylov already pointed out the importance of Rydberg/valence interaction for the photodissociation of open shell systems. 53 The situation is illustrated in Figure 5, which shows a state-to-state correlation diagram. When the electronic ground state dissociates, the electrons in the σ C-C molecular orbital (MO) will be distributed between the two fragments.…”

Section: Discussionmentioning

confidence: 99%

The photodissociation dynamics of alkyl radicals

Giegerich

Fischer

2015

The Journal of Chemical Physics

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The photodisscociation dynamics of the alkyl radicals i-propyl (CH(CH3)2) and t-butyl (C(CH3)3) are investigated by H-atom photofragment imaging. While i-propyl is excited at 250 nm, the photodynamics of t-butyl are explored over a large energy range using excitation wavelengths between 347 nm and 233 nm. The results are compared to those obtained previously for ethyl, CH3CH2, and to those reported for t-butyl using 248 nm excitation. The translational energy (ET) distribution of the H-atom photofragments is bimodal and appears rather similar for all three radicals. The low ET part of the distribution shows an isotropic photofragment angular distribution, while the high ET part is associated with a considerable anisotropy. Thus, for t-butyl, two H-atom loss channels of roughly equal importance have been identified in addition to the CH3-loss channel reported previously. A mechanism for the photodissociation of alkyl radicals is suggested that is based on interactions between Rydberg- and valence states.

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Section: Discussionmentioning

confidence: 99%

The photodissociation dynamics of alkyl radicals

Giegerich

Fischer

2015

The Journal of Chemical Physics

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“…Such states exhibit predominantly 3s character in the Franck-Condon region, but evolve increasingly towards πσ* character at extended N-H distances [13]. Of particular interest was the extent to which additional electronic states formed via Rydberg/valance mixing were contributing to the de-excitation dynamics.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast non-radiative decay of gas-phase nucleosides

Camillis

Miles

Alexander

et al. 2015

Phys. Chem. Chem. Phys.

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The ultrafast photo-physical properties of DNA are crucial in providing a stable basis for life. Although the DNA bases efficiently absorb ultraviolet (UV) radiation, this energy can be dissipated to the surrounding environment by the rapid conversion of electronic energy to vibrational energy within about a picosecond. The intrinsic nature of this internal conversion process has previously been demonstrated through gas phase experiments on the bases, supported by theoretical calculations. De-excitation rates appear to be accelerated when individual bases are hydrogen bonded to solvent molecules or their complementary Watson-Crick pair. In this paper, the first gas-phase measurements of electronic relaxation in DNA nucleosides following UV excitation are reported. Using a pump-probe ionization scheme, the lifetimes for internal conversion to the ground state following excitation at 267 nm are found to be reduced by around a factor of two for adenosine, cytidine and thymidine compared with the isolated bases. These results are discussed in terms of a recent proposition that a charge transfer state provides an additional internal conversion pathway mediated by proton transfer through a sugar to base hydrogen bond.

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“…Upon increasing methylation, the origin of the π 3s←N transition shifts strongly to the red (as does the ionization potential), whereas the V←N transition maximum shifts only slightly to the red. 10,[13][14][15] As a result, the π 3s←N bands, which in ethylene lie fairly close to the V←N Franck-Condon (FC) maximum, move relatively further to the red with methylation, until in tetramethylethylene, they are clearly isolated from the V←N transition. For 1,2-dimethylethylene and trimethylethylene, the π 3s←N bands may be overlapped with the red edge of the strong V←N bands.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

Boguslavskiy

Schalk

et al. 2011

The Journal of Chemical Physics

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Excited state unimolecular reactions of some polyenes exhibit localization of their dynamics at a single ethylenic double bond. Here we present studies of the fundamental photophysical processes in the ethylene unit itself. Combined femtosecond time-resolved photoelectron spectroscopy (TR-PES) and ab initio quantum chemical calculations was applied to the study of excited state dynamics in cis-butene, trans-butene, trimethylethylene, and tetramethylethylene, following initial excitation to their respective π 3s Rydberg states. The wavelength dependence of the π 3s Rydberg state dynamics of tetramethylethylene was investigated in more detail. The π 3s Rydberg to ππ * valence state decay rate varies greatly with substituent: the 1,2-di-and tri-methyl substituted ethylenes (cis-butene, trans-butene, and trimethylethylene) show an ultrafast decay (∼20 fs), whereas the fully methylated tetramethylethylene shows a decay rate of 2 to 4 orders of magnitude slower. These observations are rationalized in terms of topographical trends in the relevant potential energy surfaces, as found from ab initio calculations: (1) the barrier between the π 3s state and the ππ* state increases with increasing methylation, and (2) the π 3s/ππ* minimum energy conical intersection displaces monotonically away from the π 3s Franck-Condon region with increasing methylation. The use of systematic methylation in combination with TRPES and ab initio computation is emerging as an important tool in discerning the excited state dynamics of unsaturated hydrocarbons.

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Interacting Rydberg and valence states in radicals and molecules: experimental and theoretical studies

Cited by 107 publications

References 168 publications

The photodissociation dynamics of alkyl radicals

The photodissociation dynamics of alkyl radicals

Ultrafast non-radiative decay of gas-phase nucleosides

Ultrafast non-adiabatic dynamics of methyl substituted ethylenes: The π3s Rydberg state

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