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Andrzej L. Sobolewski

Bio: Andrzej L. Sobolewski is an academic researcher from Polish Academy of Sciences. The author has contributed to research in topics: Excited state & Ab initio. The author has an hindex of 51, co-authored 215 publications receiving 9481 citations. Previous affiliations of Andrzej L. Sobolewski include University of Arizona & Technische Universität München.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors combined results of ab initio electronic-structure calculations and spectroscopic investigations of jet-cooled molecules and clusters provide strong evidence of a surprisingly simple and general mechanistic picture of the nonradiative decay of biomolecules such as nucleic bases and aromatic amino acids.
Abstract: The combined results of ab initio electronic-structure calculations and spectroscopic investigations of jet-cooled molecules and clusters provide strong evidence of a surprisingly simple and general mechanistic picture of the nonradiative decay of biomolecules such as nucleic bases and aromatic amino acids. The key role in this picture is played by excited singlet states of πσ* character, which have repulsive potential-energy functions with respect to the stretching of OH or NH bonds. The 1πσ* potential-energy functions intersect not only the bound potential-energy functions of the 1ππ* excited states, but also that of the electronic ground state. Via predissociation of the 1ππ* states and a conical intersection with the ground state, the 1πσ* states trigger an ultrafast internal-conversion process, which is essential for the photostability of biomolecules. In protic solvents, the 1πσ* states promote a hydrogen-transfer process from the chromophore to the solvent. Calculations for chromophore–water clusters have shown that a spontaneous charge-separation process takes place in the solvent shell, yielding a microsolvated hydronium cation and a microsolvated electron. These results suggest that the basic mechanisms of the complex photochemistry of biomolecules in liquid water can be revealed by experimental and theoretical investigations of relatively small chromophore–water clusters.

866 citations

Journal ArticleDOI
03 Dec 2004-Science
TL;DR: Experimental and theoretical evidence is presented for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA.
Abstract: We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 ± 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited 1 ππ* state and the electronic ground state with a 1 ππ* charge-transfer state that is strongly stabilized by the transfer of a proton.

328 citations

Journal ArticleDOI
TL;DR: It is suggested that internal-conversion processes via conical intersections, which are accessed by out-of-plane deformation of the six-membered ring, dominate the photophysics of the lowest vibronic levels of adenine in the gas phase, while hydrogen-abstraction photochemistry driven by repulsive (1)pisigma states may become competitive at higher excitation energies.
Abstract: The mechanisms that are responsible for the rapid deactivation of the 1nπ* and 1ππ* excited singlet states of the 9H isomer of adenine have been investigated with multireference ab initio methods (complete-active-space self-consistent-field (CASSCF) method and second-order perturbation theory based on the CASSCF reference (CASPT2)). Two novel photochemical pathways, which lead to conical intersections of the S1 excited potential-energy surface with the electronic ground-state surface, have been identified. They involve out-of-plane deformations of the six-membered aromatic ring via the twisting of the N3C2 and N1C6 bonds. These low-lying conical intersections are separated from the minimum energy of the lowest (1nπ*) excited state in the Franck−Condon region by very low energy barriers (of the order of 0.1 eV). These properties of the S1 and S0 potential-energy surfaces explain the unusual laser-induced fluorescence spectrum of jet-cooled 9H-adenine, showing sharp structures only in a narrow energy interv...

299 citations

Journal ArticleDOI
TL;DR: The computational results support the conjecture that the photochemistry of hydrogen bonds plays a decisive role for the photostability of the molecular encoding of the genetic information in isolated DNA base pairs.
Abstract: The UV spectra of three different conformers of the guanine/cytosine base pair were recorded recently with UV-IR double-resonance techniques in a supersonic jet [Abo-Riziq, A, Grace, L, Nir, E, Kabelac, M, Hobza, P & de Vries, M S (2005) Proc Natl Acad Sci USA 102, 20–23] The spectra provide evidence for a very efficient excited-state deactivation mechanism that is specific for the Watson–Crick structure and may be essential for the photostability of DNA Here we report results of ab initio electronic-structure calculations for the excited electronic states of the three lowest-energy conformers of the guanine/cytosine base pair The calculations reveal that electron-driven interbase proton-transfer processes play an important role in the photochemistry of these systems The exceptionally short lifetime of the UV-absorbing states of the Watson–Crick conformer is tentatively explained by the existence of a barrierless reaction path that connects the spectroscopic 1π π * excited state with the electronic ground state via two electronic curve crossings For the non-Watson–Crick structures, the photochemically reactive state is located at higher energies, resulting in a barrier for proton transfer and, thus, a longer lifetime of the UV-absorbing 1π π * state The computational results support the conjecture that the photochemistry of hydrogen bonds plays a decisive role for the photostability of the molecular encoding of the genetic information in isolated DNA base pairs

287 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the low-lying excited singlet states of the guanine-cytosine base pair with multi-reference ab initio methods (complete-active-space self-consistent field (CASSCF) method and second-order perturbation theory based on the CASPT2).
Abstract: The low-lying excited singlet states of the Watson–Crick form of the guanine–cytosine base pair have been investigated with multi-reference ab initio methods (complete-active-space self-consistent-field (CASSCF) method and second-order perturbation theory based on the CASSCF reference (CASPT2)). The reaction paths and energy profiles for single proton transfer from guanine to cytosine in the 1ππ* guanine-to-cytosine charge-transfer state and for twisting of the CC double bond of the cytosine ring in the locally excited 1ππ* state of cytosine have been explored by excited-state geometry optimization using the configuration-interaction-with-singles (CIS) method and single-point energy calculations at the CASPT2 level. Avoided crossings of the 1ππ* potential-energy functions with the electronic ground-state potential-energy function have been identified along both reaction paths. The results suggest the existence of low-lying conical intersections of the 1ππ* potential-energy surface with the S0 surface which become accessible by possibly barrierless single proton transfer as well as out-of-plane deformation of cytosine and may trigger an ultrafast radiationless decay to the ground state. The relevance of these results for the rationalization of the photostability of the genetic code is briefly discussed.

268 citations


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01 Jan 2016
TL;DR: The principles of fluorescence spectroscopy is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you very much for downloading principles of fluorescence spectroscopy. As you may know, people have look hundreds times for their favorite novels like this principles of fluorescence spectroscopy, but end up in malicious downloads. Rather than reading a good book with a cup of tea in the afternoon, instead they cope with some harmful bugs inside their desktop computer. principles of fluorescence spectroscopy is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library spans in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the principles of fluorescence spectroscopy is universally compatible with any devices to read.

2,960 citations

Journal ArticleDOI
TL;DR: The Rehybridization of the Acceptor (RICT) and Planarization ofThe Molecule (PICT) III is presented, with a comparison of the effects on yield and radiationless deactivation processes.
Abstract: 6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

2,924 citations

Journal ArticleDOI
TL;DR: Proton-coupled electron transfer is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues and several are reviewed.
Abstract: ▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

2,182 citations

Journal ArticleDOI
TL;DR: In this article, a review of the multiconfiguration time-dependent Hartree (MCTDH) method for propagating wavepackets is given, and the formal derivation, numerical implementation, and performance of the method are detailed.

2,053 citations