Femtosecond photo-ionization of nucleic acid bases: electronic lifetimes and electron yields

Reuther, A.; Iglev, Hristo; Laenen, R.; Laubereau, A.

doi:10.1016/s0009-2614(00)00699-0

Cited by 72 publications

(77 citation statements)

References 15 publications

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“…As mentioned above, the native bases of DNA, in contrast to 2AP, have ultrashort excited-state decays, as reported by this laboratory, using fluorescence up-conversion [7], and by other groups, using transient absorption [20,24,25]. Our initial report of direct lifetime measurements of eight nucleotides and nucleosides support the conclusion that all these molecules undergo internal conversion to the ground state on the sub-picosecond time scale.…”

Section: The Natural Dna Basessupporting

confidence: 82%

Ultrafast decay and hydration dynamics of DNA bases and mimics

Pal

Peón

Zewail

2002

Chemical Physics Letters

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The ultrafast decay of the excited-state of DNA bases, reported here and elsewhere [Peon & Zewail, Chem. Phys. Lett. 348 (2001) 255], makes very difficult the probing of the full hydration dynamics in DNA. Here we present studies of the natural DNA base mimic, 2-aminopurine (2AP), whose excited-state decay is much longer, in water and, for comparison, in bulk ethanol. Guided by these solvation results, which directly reflect the role of orientational and translational diffusion, we reexamine the ultrafast decay rates for the natural nucleotides and nucleosides. The results are important for the mechanism of energy disposal in DNA. Ó

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Section: The Natural Dna Basessupporting

confidence: 82%

Ultrafast decay and hydration dynamics of DNA bases and mimics

Pal

Peón

Zewail

2002

Chemical Physics Letters

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“…Although the lifetime of photo-excited cytosine in solution is of the order of 1 ps [11], the possibility for intersystem crossing to a long-lived triplet state exists in the gas phase. We observe the transition to the triplet state by first exciting the molecules to the singlet state, and subsequently ionizing them with a second laser after a variable delay.…”

Section: Resultsmentioning

confidence: 99%

REMPI spectroscopy of cytosine

Nir

Müller

Grace

et al. 2002

Chemical Physics Letters

167

229

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We report resonant two-photon ionization spectra of laser desorbed, jet cooled, cytosine, 1-methyl cytosine, 5-methyl cytosine, and dimers of these. Unlike other pyrimidine bases, cytosine exhibits vibronic spectra with sharp features in two spectral regions, separated by about 5000 cm À1 . We interpret these as being due to two tautomeric forms, one keto and one enol. The dimers absorb at wavelengths that are intermediate between those of the two monomer forms. By UV-UV hole burning we determined the numbers of isomers contributing to each spectrum and by delayed two color ionization we determined triplet lifetimes. We observed hydrogen transfer between bases both in collisions between monomers and after photo-excitation in clusters. Ó

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“…Adenine is the most studied molecule from an experimental standpoint, although the contribution of at least two close-energy tautomers complicates the interpretation of the data. [1,10,11,15,[29][30][31][32] Here we report on determining the main internal conversion channels in adenine. As two tautomers of the molecule, 9H-and 7H-adenine (Figure 1), are so close in energy that they are both considered to contribute to the photophysics, not only in solution but at temperatures needed to vaporize the compound, [1,7,[31][32][33][34][35] we included them both in the study, although 7-substituted compounds have secondary biological importance.…”

Section: A C H T U N G T R E N N U N G (Np*) Ultimatelymentioning

confidence: 99%

A Three‐State Model for the Photophysics of Adenine

Serrano‐Andrés

Merchán

Borin

2006

Chemistry A European J

156

267

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An ab initio theoretical study at the CASPT2 level is reported on minimum energy reaction paths, state minima, transition states, reaction barriers, and conical intersections on the potential energy hypersurfaces of two tautomers of adenine: 9H- and 7H-adenine. The obtained results led to a complete interpretation of the photophysics of adenine and derivatives, both under jet-cooled conditions and in solution, within a three-state model. The ultrafast subpicosecond fluorescence decay measured in adenine is attributed to the low-lying conical intersection (gs/pipi* La)(CI), reached from the initially populated 1(pipi* La) state along a path which is found to be barrierless only in 9H-adenine, while for the 7H tautomer the presence of an intermediate plateau corresponding to an NH2-twisted conformation may explain the absence of ultrafast decay in 7-substituted compounds. A secondary picosecond decay is assigned to a path involving switches towards two other states, 1(pipi* Lb) and 1(npi*), ultimately leading to another conical intersection with the ground state, (gs/npi*), with a perpendicular disposition of the amino group. The topology of the hypersurfaces and the state properties explain the absence of secondary decay in 9-substituted adenines in water in terms of the higher position of the 1(npi*) state and also that the 1(pipi* Lb) state of 7H-adenine is responsible for the observed fluorescence in water. A detailed discussion comparing recent experimental and theoretical findings is given. As for other nucleobases, the predominant role of a pipi*-type state in the ultrafast deactivation of adenine is confirmed.

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Femtosecond photo-ionization of nucleic acid bases: electronic lifetimes and electron yields

Cited by 72 publications

References 15 publications

Ultrafast decay and hydration dynamics of DNA bases and mimics

Ultrafast decay and hydration dynamics of DNA bases and mimics

REMPI spectroscopy of cytosine

A Three‐State Model for the Photophysics of Adenine

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