51
|
Dobryakov AL, Ernsting NP. Lineshapes for resonant impulsive stimulated Raman scattering with chirped pump and supercontinuum probe pulses. J Chem Phys 2009; 129:184504. [PMID: 19045411 DOI: 10.1063/1.3009221] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Molecular vibrational coherence from impulsive stimulated Raman (SR) scattering, as observed by broadband transient absorption spectroscopy, is treated within the well-known third-order perturbation formalism. Shaped femtosecond optical pulses are used for the pump and supercontinuum probe fields. Dephasing is assumed to be homogeneous in the Bloch approximation. A key step requires threefold time integration over response functions and electric fields. For well-separated pulses the triple integral can be solved analytically, resulting in lineshape functions. These allow to describe the SR signal through absorption/emission/dispersion profiles which are associated with the inherent contributions. A clear physical interpretation of the amplitude and phase of the oscillatory signal is thereby obtained, and a direct connection with the vibronic structure of the molecular system is provided. Calculations for model molecular systems illustrate the spectral dependence of the vibrational coherence seen, for example, with perylene in cyclohexane. The nonoscillatory and oscillatory parts of the transient absorption spectra are compared to each other. Observed mode beatings are explained.
Collapse
Affiliation(s)
- A L Dobryakov
- Department of Chemistry, Humboldt University, D-12489 Berlin, Germany.
| | | |
Collapse
|
52
|
Zhong F, Jiang H, Gong Q. Tuning the frequency of few-cycle femtosecond laser pulses by molecular phase modulation. OPTICS EXPRESS 2009; 17:1472-1477. [PMID: 19188976 DOI: 10.1364/oe.17.001472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We demonstrate theoretically how the time-dependent phase modulation induced by molecular alignment can be used to tune the frequency of few-cycle femtosecond laser pulses continuously. Using impulsively excited alignment in N(2), the central wavelength of an initial 800 nm, 5 fs Gaussian pulse can be tuned from 324.6 to 4237.3 nm. The aligned N(2) molecules are obtained by pretransmitting another 800 nm, 100 fs linearly polarized laser pulse of intensity 3.5x10(13) Wcm(-2). The number of optical cycles contained in the frequency-tuned pulse is almost unchanged after ideal chirp compensation.
Collapse
Affiliation(s)
- Fengjiao Zhong
- Department of Physics, Peking University, Beijing, PR China
| | | | | |
Collapse
|
53
|
Hedley GJ, Ruseckas A, Liu Z, Lo SC, Burn PL, Samuel IDW. Iridium Metal Complexes as an Unambiguous Probe of Intramolecular Vibrational Redistribution. J Am Chem Soc 2008; 130:11842-3. [DOI: 10.1021/ja8036383] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gordon J. Hedley
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| | - Arvydas Ruseckas
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| | - Zehua Liu
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| | - Shih-Chun Lo
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| | - Paul L. Burn
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, United Kingdom, Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford, OX1 3TA, United Kingdom, and Centre for Organic Photonics and Electronics, School of Molecular and Microbial Sciences, University of Queensland, Chemistry Building, Queensland 4072, Australia
| |
Collapse
|
54
|
Kobayashi K, Yamagami R, Tagawa S. Effect of base sequence and deprotonation of Guanine cation radical in DNA. J Phys Chem B 2008; 112:10752-7. [PMID: 18680360 DOI: 10.1021/jp804005t] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The deprotonation of guanine cation radical (G+*) in oligonucleotides (ODNs) was measured spectroscopically by nanosecond pulse radiolysis. The G+* in ODN, produced by oxidation with SO4-*, deprotonates to form the neutral G radical (G(-H)*). In experiments using 5-substituted cytosine-modified ODN, substitution of the cytosine C5 hydrogen by a methyl group increased the rate constant of deprotonation, whereas replacement by bromine decreased the rate constant. Kinetic solvent isotope effects on the kinetics of deoxyguanosine (dG) and ODN duplexes were examined in H2O and D2O. The rate constant of formation of G(-H)* in dG was 1.7-fold larger in H2O than D2O, whereas the rate constant in the ODN duplex was 3.8-fold larger in H2O than D2O. These results suggest that the formation of G(-H)* from G+* in the ODN corresponds to the deprotonation of the oxidized hydrogen-bridged (G+*-C) base pair by a water molecule. The characteristic absorption maxima of G+* around 400 nm were shifted to a longer wavelength in the order of G<GG<GGG-containing ODNs. In contrast, the spectra of G(-H)* were not affected by the sequence and were essentially similar to that of free dG. These results suggest that the positive charge in G+* in ODN is delocalized over the extended pi orbitals of DNA base. The rate constant of the deprotonation was altered by the sequence of ODNs, where bases adjacent to guanine are important factors for deprotonation.
Collapse
Affiliation(s)
- Kazuo Kobayashi
- The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan.
| | | | | |
Collapse
|
55
|
Spectroscopy of the Potential Energy Surfaces for CH and CO Bond Activation by Transition Metal and Metal Oxide Cations. ADVANCES IN CHEMICAL PHYSICS 2008. [DOI: 10.1002/9780470259474.ch6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
|
56
|
Buchachenko AL. Chemistry on the border of two centuries — achievements and prospects. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1999v068n02abeh000487] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
57
|
Zaslonko IS. Energy exchange and reactions of highly excited polyatomic molecules. RUSSIAN CHEMICAL REVIEWS 2007. [DOI: 10.1070/rc1997v066n06abeh000222] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
58
|
Chatgilialoglu C, Caminal C, Altieri A, Vougioukalakis GC, Mulazzani QG, Gimisis T, Guerra M. Tautomerism in the guanyl radical. J Am Chem Soc 2007; 128:13796-805. [PMID: 17044708 DOI: 10.1021/ja062636h] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Despite a few decades of intense study, a full description of tautomers of one-electron-oxidized guanine remains to be achieved. Here we show that two of these tautomers are produced by the protonation of an 8-haloguanine electron adduct. The rate constants for the reactions of hydrated electrons (e(aq)(-)) with a variety of 8-substituted guanine derivatives have been measured by a pulse radiolysis technique and correlated with both inductive and resonance components of the substituents. The fate of electron adducts was investigated by radiolytic methods coupled with product studies and addressed computationally by means of time-dependent DFT (TD-B3LYP/6-311G**//B1B95/6-31+G**) calculations. The reaction of e(aq)(-) with 8-haloguanosine or 8-halo-2'-deoxyguanosine produces the first observable transient species that decay unimolecularly (k = 1 x 10(5) s(-)(1) at 22 degrees C) to give the one-electron oxidized guanosine or 2'-deoxyguanosine. Theory suggests that the electron adducts of 8-bromoguanine derivatives protonated at C8 form a pi-complex, with the Br atom situated above the molecular plane, that is prompt to eject Br(-). The two short-lived intermediates, which show a substantial difference in their absorption spectra, are recognized to be the two purine tautomers (i.e., iminic 7 and aminic 3 forms). The spin density distributions of the two tautomers are quite different at the O6 and N10 positions, whereas they are very similar at the N3, C5, and C8 positions. The resonance structures of the two tautomers are discussed in some detail. B1B95/6-31+G calculations show also that the tautomerization from the iminic (7) to the aminic (3) arrangement is a water-assisted process.
Collapse
|
59
|
Heeb LR, Peters KS. Nonadiabatic Proton/Deuteron Transfer within the Benzophenone−Triethylamine Triplet Contact Radical Ion Pair: Exploration of the Influence of Structure upon Reaction. J Phys Chem B 2007; 112:219-26. [DOI: 10.1021/jp073340g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Libby R. Heeb
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| | - Kevin S. Peters
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309
| |
Collapse
|
60
|
Carniato S, Taïeb R, Guillemin R, Journel L, Simon M, Gel’mukhanov F. K–L resonant X-ray Raman scattering as a tool for potential energy surface mapping. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.03.100] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
61
|
Dong LQ, Niu K, Cong SL. Theoretical analysis of internal conversion pathways and vibrational relaxation process of chlorophyll-a in ethyl ether solvent. Chem Phys Lett 2007. [DOI: 10.1016/j.cplett.2007.04.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
62
|
|
63
|
|
64
|
Noller B, Maksimenka R, Fischer I, Armone M, Engels B, Alcaraz C, Poisson L, Mestdagh JM. Femtosecond Dynamics of the tert-Butyl Radical, t-C4H9. J Phys Chem A 2007; 111:1771-9. [PMID: 17309242 DOI: 10.1021/jp0660839] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The excited-state dynamics of the tert-butyl radical, t-C4H9, was investigated by femtosecond time-resolved photoionization and photoelectron spectroscopy. The experiments were supported by ab initio calculations. tert-Butyl radicals, generated by flash pyrolysis of azo-tert-butane, were excited into the A 2A1 (3s) state between 347 and 307 nm and the 3p band at 274 and 268 nm and ionized by 810-nm radiation, in a [1 + 2'] or [1 + 3'] process. Electronic structure calculations confirm that the two states are of s and p Rydberg characters, respectively. The carbon framework becomes planar and thus ion-like in both states. The photoelectron spectra are broad and seem to be mediated by accidental intermediate resonances in the probe step. All time-resolved photoelectron spectra can be described by a single decay time. For the A 2A1 state, lifetimes between 180 and 69 fs were measured. Surprisingly, a much longer lifetime of around 2 ps was found for the 3p state. To understand the decay dynamics, the potential energy was computed as a function of several important nuclear coordinates. A [1,2] H-atom shift to the isobutyl radical seems not to be important for the excited-state dynamics. Qualitative considerations indicate curve crossings between the ground state, the 3s state, and a valence state along the asymmetric C-C stretch coordinate that correlates to the dimethylcarbene + methyl product channel. The implications of the present study for earlier work on the nanosecond time scale are discussed.
Collapse
Affiliation(s)
- Bastian Noller
- University of Würzburg, Institutes of Physical and Organic Chemistry, Am Hubland, D-97074 Würzburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
65
|
Lasorne B, Dive G, Desouter-Lecomte M. Wave packets in a bifurcating region of an energy landscape: Diels-Alder dimerization of cyclopentadiene. J Chem Phys 2007; 122:184304. [PMID: 15918701 DOI: 10.1063/1.1891726] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantum dynamics in a valley ridge inflection (VRI) point region is analyzed in the case of the Diels-Alder endo-dimerization of cyclopentadiene pointed out recently by [Caramella et al., J. Am. Chem. Soc. 124, 1130 (2002)]. The VRI point is located along the reaction path connecting the bispericyclic symmetrical transition structure put in evidence by Caramella et al. and the transition state of the Cope rearrangement. Dynamics is carried out by using constrained Hamiltonian methodology. The active coordinates are the first formed C-C bond length and the difference between the two other C-C bond lengths which achieve the dimerization as 4+2 or 2+4 adducts. A two-dimensional (2D) minimum-energy surface have been computed at the Becke 3 Lee-Yong-Parr6-31G* level. The energy landscape can be classified as an uphill ridge-pitchfork VRI bifurcation according to a recent classification of bifurcation events [W. Quapp, J. Mol. Struct. 695-696, 95 (2004)]. Dynamics does not describe the thermal reaction but concerns wave packets which could be prepared by pulse reagents, i.e., by coherent control. We analyze how the shape and initial location on the ground potential-energy surface are linked to the synchronous or asynchronous mechanism of the final step after the first transition state. We use a one-dimensional model of optimum control theory to check the feasibility of such a coherent preparation. The wave-packet evolution in the VRI domain is well explained by semiclassical predictions even with the negative curvature of the unstable ridge. Finally, a crude model of dissipation has been introduced to test the stability of the 2D predictions.
Collapse
Affiliation(s)
- B Lasorne
- Laboratoire de Chimie Physique [Unité Mixte de Recherche (UMR) 8000], Université Paris-Sud, Centre Scientifique d'Orsay, F-91405 Orsay Cedex, France
| | | | | |
Collapse
|
66
|
Robb MA, Garavelli M, Olivucci M, Bernardi F. A Computational Strategy for Organic Photochemistry. REVIEWS IN COMPUTATIONAL CHEMISTRY 2007. [DOI: 10.1002/9780470125922.ch2] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
67
|
Nuernberger P, Vogt G, Brixner T, Gerber G. Femtosecond quantum control of molecular dynamics in the condensed phase. Phys Chem Chem Phys 2007; 9:2470-97. [PMID: 17508081 DOI: 10.1039/b618760a] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We review the progress in controlling quantum dynamical processes in the condensed phase with femtosecond laser pulses. Due to its high particle density the condensed phase has both high relevance and appeal for chemical synthesis. Thus, in recent years different methods have been developed to manipulate the dynamics of condensed-phase systems by changing one or multiple laser pulse parameters. Single-parameter control is often achieved by variation of the excitation pulse's wavelength, its linear chirp or its temporal subpulse separation in case of pulse sequences. Multiparameter control schemes are more flexible and provide a much larger parameter space for an optimal solution. This is realized in adaptive femtosecond quantum control, in which the optimal solution is iteratively obtained through the combination of an experimental feedback signal and an automated learning algorithm. Several experiments are presented that illustrate the different control concepts and highlight their broad applicability. These fascinating achievements show the continuous progress on the way towards the control of complex quantum reactions in the condensed phase.
Collapse
Affiliation(s)
- Patrick Nuernberger
- Universität Würzburg, Physikalisches Institut, Am Hubland, 97074 Würzburg, Germany
| | | | | | | |
Collapse
|
68
|
Dong LQ, Niu K, Cong SL. Theoretical study of vibrational relaxation and internal conversion dynamics of chlorophyll-a in ethyl acetate solvent in femtosecond laser fields. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.10.040] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
69
|
Martiny CPJ, Madsen LB. Symmetry of carrier-envelope phase difference effects in strong-field, few-cycle ionization of atoms and molecules. PHYSICAL REVIEW LETTERS 2006; 97:093001. [PMID: 17026358 DOI: 10.1103/physrevlett.97.093001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Indexed: 05/12/2023]
Abstract
In few-cycle pulses, the exact value of the carrier-envelope phase difference (CEPD) has a pronounced influence on the ionization dynamics of atoms and molecules. We show that, for atoms in circularly polarized light, a change in the CEPD is mapped uniquely to an overall rotation of the system, and results for arbitrary CEPD are obtained by rotation of the results from a single calculation with fixed CEPD. For molecules, this is true only for linear molecules aligned parallel with the propagation direction of the field. The effects of CEPD are classified as geometric or nongeometric. The observations are exemplified by strong-field calculations on hydrogen.
Collapse
|
70
|
Jena P, Castleman AW. Clusters: a bridge across the disciplines of physics and chemistry. Proc Natl Acad Sci U S A 2006; 103:10560-9. [PMID: 16835306 PMCID: PMC1636021 DOI: 10.1073/pnas.0601782103] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Puru Jena
- *Department of Physics, Virginia Commonwealth University, Richmond, VA 23284; and
- To whom correspondence may be addressed. E-mail:
or
| | - A. W. Castleman
- Departments of Chemistry and Physics, Pennsylvania State University, University Park, PA 16802
- To whom correspondence may be addressed. E-mail:
or
| |
Collapse
|
71
|
Braun M, Sobotta C, Dürr R, Pulvermacher H, Malkmus S. Analysis of Wave Packet Motion in Frequency and Time Domain: Oxazine 1. J Phys Chem A 2006; 110:9793-800. [PMID: 16898679 DOI: 10.1021/jp057543l] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Wave packet motion in the laser dye oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral range of 600-690 nm was accessible by amplified broadband probe pulses covering the overlap region of ground-state bleach and stimulated emission signal. The influence of vibrational wave packets on the optical signal is analyzed in the frequency domain and the time domain. For the analysis in the frequency domain an algorithm is presented that accounts for interference effects of neighbored vibrational modes. By this method amplitude, phase and decay time of vibrational modes are retrieved as a function of probe wavelength and distortions due to neighbored modes are reduced. The analysis of the data in the time domain yields complementary information on the intensity, central wavelength, and spectral width of the optical bleach spectrum due to wave packet motion.
Collapse
Affiliation(s)
- Markus Braun
- Lehrstuhl für BioMolekulare Optik, Department für Physik, Ludwig-Maximilians-Universität München, Oettingenstrasse 67, D-80538 München, Germany.
| | | | | | | | | |
Collapse
|
72
|
Théberge F, Aközbek N, Liu W, Becker A, Chin SL. Tunable ultrashort laser pulses generated through filamentation in gases. PHYSICAL REVIEW LETTERS 2006; 97:023904. [PMID: 16907449 DOI: 10.1103/physrevlett.97.023904] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Indexed: 05/11/2023]
Abstract
Tunable and stable ultrashort laser pulses in the visible spectrum are generated with high efficiency by four-wave mixing process during the filamentation of near-infrared and infrared laser pulses in gases. It is shown that these tunable ultrashort pulses have a very low energy fluctuation and an excellent mode quality due to the processes of intensity clamping and self-filtering in the filament.
Collapse
Affiliation(s)
- Francis Théberge
- Centre d'Optique, Photonique et Laser, COPL, and Département de physique, de génie physique et d'optique, Université Laval, Québec, Québec G1K 7P4, Canada
| | | | | | | | | |
Collapse
|
73
|
Heeb LR, Peters KS. Further Evidence of an Inverted Region in Proton Transfer within the Benzophenone/Substituted Aniline Contact Radical Ion Pairs; Importance of Vibrational Reorganization Energy. J Phys Chem A 2006; 110:6408-14. [PMID: 16706395 DOI: 10.1021/jp056188w] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of proton transfer within the triplet contact radical ion pair of a variety of substituted benzophenones with N,N-diethylaniline, N,N-dimethyl-p-toluinide, and N,N-diallylaniline are examined in solvents of varying polarity. The correlation of the rate constants with driving force reveal both a normal region and an inverted region providing support for the nonadiabatic nature of proton transfer within these systems. The reorganization of both the solvent and the molecular framework are central in governing the overall reaction dynamics.
Collapse
Affiliation(s)
- Libby R Heeb
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, USA
| | | |
Collapse
|
74
|
Yamakita Y, Isogai Y, Ohno K. Large Raman-scattering activities for the low-frequency modes of substituted benzenes: Induced polarizability and stereo-specific ring-substituent interactions. J Chem Phys 2006; 124:104301. [PMID: 16542073 DOI: 10.1063/1.2163344] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The large nonresonant Raman-scattering activities of the out-of-plane bending and torsional modes of monosubstituted benzene analogs are studied by low-frequency Raman experiments and B3LYP6-31++G(d,p) calculations. Electronic interactions between the sigma orbitals of the substituent and the pi orbitals of the ring are found to enhance the Raman activities, depending on the substituent and its conformation. In the case of tert-butylbenzene [C6H5C(CH3)3] and trimethylphenylsilane [C6H5Si(CH3)3], three single bonds which are linked to the alpha atom of the substituent have low rotational barriers around the joint bond. Nearly free rotation of the substituents leads to a significant probability for one of the single bonds to occupy a conformation close to the vertical configuration with respect to the ring at room temperature. The resultant sigma-pi electronic interaction gives rise to the large Raman activities. In contrast, those possessing a single bond in a coplanar (or nearly coplanar) configuration at the most stable equilibrium state, i.e., anisole (C6H5OCH3), thioanisole (C6H5SCH3), and N-methylaniline (C6H5NHCH3), display no prominent Raman bands for the low-frequency vibrational modes. In these molecules, the sigma-pi conjugation does not take place due to the orthogonal orientation of the orbitals. Strong conformational dependence of the sigma-pi Raman enhancement is clearly obtained for the metastable vertical conformer of thioanisole, for which Raman activities are one-order magnitude greater than those of the coplanar conformer.
Collapse
Affiliation(s)
- Yoshihiro Yamakita
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Sendai 980-8578, Japan.
| | | | | |
Collapse
|
75
|
Sibert EL, Gruebele M. Molecular vibrational energy flow and dilution factors in an anharmonic state space. J Chem Phys 2006; 124:024317. [PMID: 16422593 DOI: 10.1063/1.2155432] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A fourth-order resonance Hamiltonian is derived from the experimental normal-mode Hamiltonian of SCCl2. The anharmonic vibrational state space constructed from the effective Hamiltonian provides a realistic model for vibrational energy flow from bright states accessible by pulsed laser excitation. We study the experimentally derived distribution PE(sigma) of dilution factors sigma as a function of energy. This distribution characterizes the dynamics in the long-time limit. State space models predict that PE(sigma) should be bimodal, with some states undergoing facile intramolecular vibrational energy redistribution (small sigma), while others at the same total energy remain "protected" (sigma approximately 1). The bimodal distribution is in qualitative agreement with analytical and numerical local density of states models. However, there are fewer states protected from energy flow, and the protected states begin to fragment at higher energy, shifting from sigma approximately 1 to sigma approximately 0.5. We also examine how dilution factors are distributed in the vibrational state space of SCCl2 and how the power law specifying the survival probability of harmonic initial states correlates with the dilution factor distribution of anharmonic initial states.
Collapse
Affiliation(s)
- Edwin L Sibert
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | | |
Collapse
|
76
|
|
77
|
Malkmus S, Dürr R, Sobotta C, Pulvermacher H, Zinth W, Braun M. Chirp Dependence of Wave Packet Motion in Oxazine 1. J Phys Chem A 2005; 109:10488-92. [PMID: 16834303 DOI: 10.1021/jp054462g] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The motion of vibrational wave packets in the system oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral properties of the probe pulse from 600 to 700 nm were chosen to cover the overlap region where ground-state bleach and stimulated emission signals are detected. The spectral phase of the pump pulse was manipulated by a liquid crystal display based pulse-shaping setup. Chirped excitation pulses of negative and positive chirp can be used to excite vibrational modes predominantly in the ground or excited state, respectively. To distinguish the observed wave packets in oxazine 1 moving in the ground or excited state, spectrally resolved transient absorption experiments are performed for various values of the linear chirp of the pump pulses. The amplitudes of the wave packet motion show an asymmetric behavior with an optimum signal for a negative chirp of -0.75 +/- 0.2 fs/nm, which indicates that predominantly ground-state wave packets are observed.
Collapse
Affiliation(s)
- Stephan Malkmus
- Department für Physik, Ludwig-Maximilians-Universität, Oettingenstrasse 67, D-80538 Munich, Germany
| | | | | | | | | | | |
Collapse
|
78
|
Nagasawa Y, Mori Y, Nakagawa Y, Miyasaka H, Okada T. Enhancement and Suppression of Vibrational Coherence in Degenerate Four-Wave-Mixing Signal Generated from Dye-Doped Polymer Films. J Phys Chem B 2005; 109:11946-52. [PMID: 16852472 DOI: 10.1021/jp051187p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vibrational coherence in the degenerate four-wave-mixing (DFWM) signal generated from polymer films doped with a dye, oxazine 4 (Ox4), at 10 K was investigated. It was found that the amplitudes of some low-frequency oscillations (<400 cm(-1)) were enhanced when the delay between the first and second femtosecond pulses was set out of phase with the oscillation period. Frequency and reorganization energy dependence was investigated by computer simulation based on the response function formalism which considers all the possible Liouville space pathways for the DFWM signal. It was revealed that low-frequency oscillations with weak coupling to the optical transition can be enhanced in the stimulated photon echo signal compared to the transient grating signal.
Collapse
Affiliation(s)
- Yutaka Nagasawa
- Division of Frontier Materials Science, Graduate School of Engineering Science, and Research Center for Materials Science at Extreme Conditions, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | | | | | | | | |
Collapse
|
79
|
Mabbs R, Pichugin K, Sanov A. Time-resolved imaging of the reaction coordinate. J Chem Phys 2005; 122:174305. [PMID: 15910030 DOI: 10.1063/1.1887170] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Time-resolved photoelectron imaging of negative ions is employed to study the dynamics along the reaction coordinate in the photodissociation of IBr(-). The results are discussed in a side-by-side comparison with the dissociation of I(2) (-), examined under similar experimental conditions. The I(2) (-) anion, extensively studied in the past, is used as a reference system for interpreting the IBr(-) results. The data provide rigorous dynamical tests of the anion electronic potentials. The evolution of the energetics revealed in the time-resolved (780 nm pump, 390 nm probe) I(2) (-) and IBr(-) photoelectron images is compared to the predictions of classical trajectory calculations, with the time-resolved photoelectron spectra modeled assuming a variety of neutral states accessed in the photodetachment. In light of good overall agreement of the experimental data with the theoretical predictions, the results are used to construct an experimental image of the IBr(-) dissociation potential as a function of the reaction coordinate.
Collapse
Affiliation(s)
- Richard Mabbs
- Department of Chemistry, University of Arizona, Tucson, 85721-0041, USA
| | | | | |
Collapse
|
80
|
Guimarães F, Gel’mukhanov F, Cesar A, Ågren H. Quantum wave packet revivals in IR+X-ray pump–probe spectroscopy. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.02.061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
81
|
Gentili P, Romani A, Becker R, Favaro G. The photoinduced ring opening reaction of benzo(2H)chromenes: a kinetic and thermodynamic approach. Chem Phys 2005. [DOI: 10.1016/j.chemphys.2004.09.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
82
|
Paterson MJ, Bearpark MJ, Robb MA, Blancafort L, Worth GA. Conical intersections: A perspective on the computation of spectroscopic Jahn–Teller parameters and the degenerate ‘intersection space’. Phys Chem Chem Phys 2005; 7:2100-15. [DOI: 10.1039/b416538a] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
83
|
Neumark DM. Probing the transition state with negative ion photodetachment: experiment and theory. Phys Chem Chem Phys 2005; 7:433-42. [DOI: 10.1039/b417886f] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
84
|
Sun L, Bu Y. Marked Variations of Dissociation Energy and H-Bond Character of the Guanine-Cytosine Base Pair Induced by One-Electron Oxidation and Li+ Cation Coupling. J Phys Chem B 2004; 109:593-600. [PMID: 16851051 DOI: 10.1021/jp0459817] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The variation of dissociation energy and H-bond character of the G-C cation and the Li-GC cation have been investigated by employing density functional theory (B3LYP) with the 6-31+G* basis set. The one-electron oxidation and the coupling of Li(+) to the guanine-cytosine base pair can strengthen the interaction between guanine and cytosine. The interaction of the cation Li(+) with guanine is attractive and is attributed to the polarization of the H-bonds between G-C that enhances G-C interaction. The cooperativity of the three H-bonds in the GC and Li-GC cations is different from that in the neutral GC base pair. The proton-transfer process between N(1) of the guanine and N(3) of the cytosine can occur in the GC cation and the Li-GC cation. The geometries of the transition state are out of plane, especially for the transition state of the Li-GC cation. The analysis of the activation energy for the proton-transfer process shows that the GC(+) before and after proton transfer can exist simultaneously in the gas phase, but for the Li-GC(+) system, the Li-GC(+) without proton transfer is the dominating species in the gas phase.
Collapse
Affiliation(s)
- Lixiang Sun
- Institute of Theoretical Chemistry, Shandong University, Jinan, 250100, P. R. China
| | | |
Collapse
|
85
|
Affiliation(s)
- T E Dermota
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | | | | |
Collapse
|
86
|
Peters KS, Kim G. Characterization of Solvent and Deuterium Isotope Effects on Nonadiabatic Proton Transfer in the Benzophenone/N,N-Dimethylaniline Contact Radical Ion Pair. J Phys Chem A 2004. [DOI: 10.1021/jp031237v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kevin S. Peters
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
| | - Ganghyeok Kim
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215
| |
Collapse
|
87
|
Peters KS, Kim G. Kinetic isotope effects for non-adiabatic proton transfer in benzophenone?N-methylacridan contact radical ion pairs. J PHYS ORG CHEM 2004. [DOI: 10.1002/poc.849] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
88
|
Bu L, Straub JE. Simulating Vibrational Energy Flow in Proteins: Relaxation Rate and Mechanism for Heme Cooling in Cytochrome c. J Phys Chem B 2003. [DOI: 10.1021/jp0351728] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lintao Bu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215
| | - John E. Straub
- Department of Chemistry, Boston University, Boston, Massachusetts 02215
| |
Collapse
|
89
|
Bu L, Straub JE. Vibrational frequency shifts and relaxation rates for a selected vibrational mode in cytochrome C. Biophys J 2003; 85:1429-39. [PMID: 12944260 PMCID: PMC1303319 DOI: 10.1016/s0006-3495(03)74575-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The vibrational energy relaxation of a selected vibrational mode in cytochrome c--a C-D stretch in the terminal methyl group of Met80--has been studied using equilibrium molecular dynamics simulation and normal mode analysis methods. As demonstrated in the pioneering work of Romesberg and co-workers, isotopic labeling of the C-H (to C-D) stretch in alkyl side chains shifts the stretching frequency to the transparent region of the protein's density of states, making it an effective and versatile probe of protein structure and dynamics. Molecular dynamics trajectories of solvated cytochrome c were run at 300 K, and vibrational population relaxation times were estimated using the classical Landau-Teller-Zwanzig model and a number of semiclassical theories of resonant and two-phonon vibrational relaxation processes. The C-D stretch vibrational population relaxation time is estimated to be T(1) = 14-40 ps; the relatively close agreement between various semiclassical estimates of T(1) lends support to the applicability of those expressions. Normal mode calculations were used to identify the dominant coupling between the protein and C-D oscillator. All bath modes strongly coupled to the C-D stretch are in close proximity. Angle bending modes in the terminal methyl group of Met80 appear to be the most likely acceptor modes defining the mechanism of population relaxation of the C-D vibration.
Collapse
Affiliation(s)
- Lintao Bu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | | |
Collapse
|
90
|
Bu L, Straub JE. Vibrational Energy Relaxation of “Tailored” Hemes in Myoglobin Following Ligand Photolysis Supports Energy Funneling Mechanism of Heme “Cooling”. J Phys Chem B 2003. [DOI: 10.1021/jp034558f] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lintao Bu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215
| | - John E. Straub
- Department of Chemistry, Boston University, Boston, Massachusetts 02215
| |
Collapse
|
91
|
Kobayashi K, Tagawa S. Direct observation of guanine radical cation deprotonation in duplex DNA using pulse radiolysis. J Am Chem Soc 2003; 125:10213-8. [PMID: 12926943 DOI: 10.1021/ja036211w] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The dynamics of one-electron oxidation of guanine (G) base mononucleotide and that in DNA have been investigated by pulse radiolysis. The radical cation (G+*) of deoxyguanosine (dG), produced by oxidation with SO(4)-*, rapidly deprotonates to form the neutral G radical (G(-H)*) with a rate constant of 1.8 x 10(7) s(-1) at pH 7.0, as judged from transient spectroscopy. With experiments using different double-stranded oligonucleotides containing G, GG, and GGG sequences, the absorbance increases at 625 nm, characteristic of formation of the G(-H)*, were found to consist of two phases. The rate constants of the faster ( approximately 1.3 x 10(7) s(-1)) and slower phases ( approximately 3.0 x 10(6) s(-1)) were similar for the different oligonucleotides. On the other hand, in the oligonucleotide containing G located at the 5'- and 3'-terminal positions, only the faster phase was seen. These results suggest that the lifetime of the radical cation of the G:C base pair (GC+*), depending on its location in the DNA chain, is longer than that of free dG. In addition, the absorption spectral intermediates showed that hole transport to a specific G site within a 12-13mer double-stranded oligonucleotide is complete within 50 ns; that is, the rate of hole transport over 20 A is >10(7) s(-1).
Collapse
Affiliation(s)
- Kazuo Kobayashi
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki Osaka 567-0047, Japan.
| | | |
Collapse
|
92
|
Abstract
Ultrafast lasers, which generate optical pulses in the picosecond and femtosecond range, have progressed over the past decade from complicated and specialized laboratory systems to compact, reliable instruments. Semiconductor lasers for optical pumping and fast optical saturable absorbers, based on either semiconductor devices or the optical nonlinear Kerr effect, have dramatically improved these lasers and opened up new frontiers for applications with extremely short temporal resolution (much smaller than 10 fs), extremely high peak optical intensities (greater than 10 TW/cm2) and extremely fast pulse repetition rates (greater than 100 GHz).
Collapse
Affiliation(s)
- Ursula Keller
- Physics Department, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland.
| |
Collapse
|
93
|
Gauduel Y, Hallou A, Charles B. Short-Time Water Caging and Elementary Prehydration Redox Reactions in Ionic Environments. J Phys Chem A 2003. [DOI: 10.1021/jp021745p] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Y. Gauduel
- Laboratoire d'Optique Appliquée, CNRS UMR 7639 and INSERM U451, Ecole Polytechnique−ENS Techniques Avancées, 91761 Palaiseau Cedex, France
| | - A. Hallou
- Laboratoire d'Optique Appliquée, CNRS UMR 7639 and INSERM U451, Ecole Polytechnique−ENS Techniques Avancées, 91761 Palaiseau Cedex, France
| | - B. Charles
- Laboratoire d'Optique Appliquée, CNRS UMR 7639 and INSERM U451, Ecole Polytechnique−ENS Techniques Avancées, 91761 Palaiseau Cedex, France
| |
Collapse
|
94
|
Biomolecular conformations can be identified as metastable sets of molecular dynamics. HANDBOOK OF NUMERICAL ANALYSIS 2003. [DOI: 10.1016/s1570-8659(03)10013-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
95
|
Leskiw BD, Knappenberger KL, Castleman AW. Relaxation dynamics of the electronically excited vanadium Met–Car cluster. J Chem Phys 2002. [DOI: 10.1063/1.1512653] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
96
|
Keshavamurthy S, Cerruti NR, Tomsovic S. Analyzing intramolecular vibrational energy redistribution via the overlap intensity-level velocity correlator. J Chem Phys 2002. [DOI: 10.1063/1.1496471] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
97
|
Stert V, Ritze HH, Radloff W. Ultrafast intracluster reaction in Ba⋯FCH3 excited to the electronic B̃ state. Chem Phys Lett 2002. [DOI: 10.1016/s0009-2614(02)00109-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
98
|
|
99
|
Morlet-Savary F, Ley C, Jacques P, Fouassier JP. Photophysics of a Bridged 7-Diethylamino-4-methyl-coumarin C102: Studying the Hydrogen Bonding Effect by Time Resolved Stimulated Emission. J Phys Chem A 2001. [DOI: 10.1021/jp010753n] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- F. Morlet-Savary
- Département de Photochimie Générale, CNRS UMR n°7525, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 Rue Alfred Werner, 68093 Mulhouse Cedex, France
| | - C. Ley
- Département de Photochimie Générale, CNRS UMR n°7525, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 Rue Alfred Werner, 68093 Mulhouse Cedex, France
| | - P. Jacques
- Département de Photochimie Générale, CNRS UMR n°7525, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 Rue Alfred Werner, 68093 Mulhouse Cedex, France
| | - J. P. Fouassier
- Département de Photochimie Générale, CNRS UMR n°7525, Ecole Nationale Supérieure de Chimie de Mulhouse, 3 Rue Alfred Werner, 68093 Mulhouse Cedex, France
| |
Collapse
|
100
|
Affiliation(s)
- H Sato
- Laser Photochemistry Research Group, Department of Chemistry for Materials, Faculty of Engineering, Mi'e University, 1515 Kamihamacho, Tsu 514-8507, Japan.
| |
Collapse
|