201
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Fridgen TD. Structures of Heterogeneous Proton-Bond Dimers with a High Dipole Moment Monomer: Covalent vs Electrostatic Interactions. J Phys Chem A 2006; 110:6122-8. [PMID: 16671683 DOI: 10.1021/jp057335t] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A number of calculated structures of heterogeneous proton-bound dimers containing monomers such as acetonitrile, cyanamide, vinylene carbonate, and propiolactone, which have high dipole moments, are presented. These proton-bound dimers are predicted to have a structural anomaly pertaining to the bond distances between the central proton and the basic sites on each of the monomers. The monomers with the high dipole moments also have the larger proton affinity and, on the basis of difference in proton affinities, it would be expected that the proton would be closer to this monomer than the one with the lower proton affinity. However, the proton is found to lie substantially closer to the monomer with the lower proton affinity in most cases, unless the difference in proton affinity is too large. Simply stated, the difference in proton affinities is smaller than the difference in the affinity to form an ion-dipole complex for the two monomers and it is the larger affinity for the high dipole moment monomer (which also has the higher proton affinity) to form an ion-dipole complex that is responsible for the proton lying closer to the low proton affinity monomer. The bond distances between the central proton and the monomers are found to be related to the difference in proton affinity. It is found, though, that the proton-bound dimers can be grouped into two separate groups, one where the proton-bound dimer contains a high dipole moment monomer and one group where the proton-bound dimer does not contain a high dipole moment monomer. From these plots it has been determined that a high dipole moment monomer is one that has a dipole moment greater than 2.9 D.
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Affiliation(s)
- Travis D Fridgen
- Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, Canada A1C 5S7.
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202
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Szpunar DE, Kautzman KE, Faulhaber AE, Neumark DM. Photofragment coincidence imaging of small I−(H2O)n clusters excited to the charge-transfer-to-solvent state. J Chem Phys 2006; 124:054318. [PMID: 16468880 DOI: 10.1063/1.2165202] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation dynamics of small I-(H2O)n(n=2-5) clusters excited to their charge-transfer-to-solvent (CTTS) states have been studied using photofragment coincidence imaging. Upon excitation to the CTTS state, two photodissociation channels were observed. The major channel (approximately 90%) is a two-body process forming neutral I+(H2O)n photofragments, and the minor channel is a three-body process forming I+(H2O)n-1+H2O fragments. Both processes display translational energy [P(ET)] distributions peaking at ET=0 with little available energy partitioned into translation. Clusters excited to the detachment continuum rather than to the CTTS state display the same two channels with similar P(ET) distributions. The observation of similar P(ET) distributions from the two sets of experiments suggests that in the CTTS experiments, I atom loss occurs after autodetachment of the excited [I(H2O)n-]* cluster or, less probably, that the presence of the excess electron has little effect on the departing I atom.
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Affiliation(s)
- David E Szpunar
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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203
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Maeyama T, Negishi Y, Tsukuda T, Yagi I, Mikami N. Electron localization in negatively charged formamide clusters studied by photodetachment spectroscopy. Phys Chem Chem Phys 2006; 8:827-33. [PMID: 16482324 DOI: 10.1039/b514656a] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Size-dependent features of the electron localization in negatively charged formamide clusters (FAn-, n = 5-21) have been studied by photodetachment spectroscopy. In the photoelectron spectra for all the sizes studied, two types of bands due to different isomers of anions were found. The low binding energy band peaking around 1 eV is assigned to the solvated electron state by relative photodetachment cross-section measurements in the near-infrared region. It is suggested that nascent electron trapping is dominated by formation of the solvated electron. The higher energy band originates from the covalent anion state generated after a significant relaxation process, which exhibits a rapid increase of electron binding energy as a function of the cluster size. A unique behavior showing a remarkable band intensity of the higher energy band was found only for n = 9.
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Affiliation(s)
- Toshihiko Maeyama
- Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan.
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204
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Herbert JM, Head-Gordon M. Accuracy and limitations of second-order many-body perturbation theory for predicting vertical detachment energies of solvated-electron clusters. Phys Chem Chem Phys 2006; 8:68-78. [PMID: 16482246 DOI: 10.1039/b513098k] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Vertical electron detachment energies (VDEs) are calculated for a variety of (H(2)O)(n)(-) and (HF)(n)(-) isomers, using different electronic structure methodologies but focusing in particular on a comparison between second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster theory with noniterative triples, CCSD(T). For the surface-bound electrons that characterize small (H(2)O)(n)(-) clusters (n< or = 7), the correlation energy associated with the unpaired electron grows linearly as a function of the VDE but is unrelated to the number of monomers, n. In every example considered here, including strongly-bound "cavity" isomers of (H(2)O)(24)(-), the correlation energy associated with the unpaired electron is significantly smaller than that associated with typical valence electrons. As a result, the error in the MP2 detachment energy, as a fraction of the CCSD(T) value, approaches a limit of about -7% for (H(2)O)(n)(-) clusters with VDEs larger than about 0.4 eV. CCSD(T) detachment energies are bounded from below by MP2 values and from above by VDEs calculated using second-order many-body perturbation theory with molecular orbitals obtained from density functional theory. For a variety of both strongly- and weakly-bound isomers of (H(2)O)(20)(-) and (H(2)O)(24)(-), including both surface states and cavity states, these bounds afford typical error bars of +/-0.1 eV. We have found only one case where the Hartree-Fock and density functional orbitals differ qualitatively; in this case the aforementioned bounds lie 0.4 eV apart, and second-order perturbation theory may not be reliable.
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Affiliation(s)
- John M Herbert
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.
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205
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Kalcher J. Singlet-triplet splittings and ground- and excited-state electron affinities of selected cyanosilylenes, XSiCN (X = H, F, Cl, CH3, SiH3, CN). J Phys Chem A 2005; 109:11437-42. [PMID: 16354033 DOI: 10.1021/jp0534840] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Several cyanosilylenes, XSiCN, (X = H, F, Cl, CH3, SiH3, CN) have been investigated using the RHF-ACPF and CAS(2,2)-ACPF methods in conjunction with the aug-cc-pVTZ basis sets. All silylenes are found to have singlet ground states. The ground-state electron affinities are found to be rather high, i.e., 1.832, 1.497, 1.896, 1.492, 2.235, and 2.631 eV for HSiCN, FSiCN, ClSiCN, H3CSiCN, H3SiSiCN, and Si(CN)2, respectively. The existence of bound excited negative ion states has been discovered for the first time within these silylenes. All these bound excited anion states belong to the totally symmetric irreducible representations and can be characterized as dipole-bound negative ion states. All triplet excited states have even larger dipole moments than the singlet states and are, therefore, "dressed" by dipole-bound negative ion states, which correspond to Feshbach resonances.
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Affiliation(s)
- Josef Kalcher
- Karl-Franzens-Universität, Institut für Chemie, Strassoldogasse 10, A-8010 Graz, Austria.
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206
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Frigato T, Svozil D, Jungwirth P. Valence- and Dipole-Bound Anions of the Thymine−Water Complex: Ab Initio Characterization of the Potential Energy Surfaces. J Phys Chem A 2005; 110:2916-23. [PMID: 16509613 DOI: 10.1021/jp054090b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The potential energy surfaces of the neutral and anionic thymine-water complexes are investigated using high-level ab initio calculations. Both dipole-bound (DB) and valence-bound (VB) anionic forms are considered. Four minima and three first-order stationary points are located, and binding energies are computed. All minima, for both anions, are found to be vertically and adiabatically stable. The binding energies are much higher for valence-bound than for dipole-bound anions. Adiabatic electron affinities are in the 66-287 meV range for VB anions and the 4-60 meV range for DB anions, and vertical detachment energies are in the 698-977 meV and 10-70 meV range for VB and DB anions, respectively. For cases where literature data are available, the computed values are in good agreement with previous experimental and theoretical studies. It is observed that electron attachment modifies the shape of the potential energy surfaces of the systems, especially for the valence-bound anions. Moreover, for both anions the size of the energy barrier between the two lowest energy minima is strongly reduced, rendering the coexistence of different structures more probable.
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Affiliation(s)
- Tomaso Frigato
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic
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207
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Singh NJ, Olleta AC, Kumar A, Park M, Yi HB, Bandyopadhyay I, Lee HM, Tarakeshwar P, Kim KS. Study of interactions of various ionic species with solvents toward the design of receptors. Theor Chem Acc 2005. [DOI: 10.1007/s00214-005-0057-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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208
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Baletto F, Cavazzoni C, Scandolo S. Surface trapped excess electrons on ice. PHYSICAL REVIEW LETTERS 2005; 95:176801. [PMID: 16383853 DOI: 10.1103/physrevlett.95.176801] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2005] [Indexed: 05/05/2023]
Abstract
Local trapping of excess electrons at the surface of solid water systems has recently been observed in large water clusters and at the ice/vacuum interface. The existence of stable surface-bound states for the excess electron may have important implications in atmospheric chemistry, electrochemistry, and radiation physics. By means of first-principles molecular dynamics we find that excess electrons induce a structural reconstruction of the ice surface on a time scale of a fraction of a picosecond. The surface molecular rearrangement leads to an increase of the number of dangling OH bonds pointing towards the vacuum and to the appearance of an electrostatic barrier preventing the penetration of the electron in the bulk. Both factors imply a remarkable stability for the surface-bound excess electron, with respect to its decay into the bulk solvated state.
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Affiliation(s)
- Francesca Baletto
- The Abdus Salam International Centre of Theoretical Physics, INFM/Democritos National Simulation Center, Strada Costiera 11, 34100 Trieste, Italy
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209
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Sommerfeld T, Jordan KD. Quantum Drude Oscillator Model for Describing the Interaction of Excess Electrons with Water Clusters: An Application to (H2O)13-. J Phys Chem A 2005; 109:11531-8. [PMID: 16354045 DOI: 10.1021/jp053768k] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cluster anions for which the excess electron occupies an extended nonvalence orbital can be described by use of a model Hamiltonian employing quantum Drude oscillators to represent the polarizable charge distributions of the monomers. In this work, a Drude model for water cluster anions is described and used to investigate the (H2O)13(-) cluster. Several low-energy isomers are characterized, and the finite-temperature properties of the cluster are investigated by means of parallel tempering Monte Carlo simulations. Two structural motifs, one with double-acceptor water monomers and the other with four-membered rings of double-acceptor single-donor monomers with four free OH groups pointed in the same direction, are found to lead to large (approximately > eV) electron binding energies. The distributions of the computed vertical detachment energies qualitatively reproduce the experimentally measured photoelectron spectrum, and our simulations indicate that both of the main peaks in the measured spectrum derive from several isomers.
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Affiliation(s)
- Thomas Sommerfeld
- University of Pittsburgh, Department of Chemistry, and Center for Molecular and Materials Simulation, Chevron Science Center, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260, USA.
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210
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Bragg AE, Verlet JRR, Kammrath A, Cheshnovsky O, Neumark DM. Electronic Relaxation Dynamics of Water Cluster Anions. J Am Chem Soc 2005; 127:15283-95. [PMID: 16248671 DOI: 10.1021/ja052811e] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The electronic relaxation dynamics of water cluster anions, (H(2)O)(n)(-), have been studied with time-resolved photoelectron imaging. In this investigation, the excess electron was excited through the p<--s transition with an ultrafast laser pulse, with subsequent electronic evolution monitored by photodetachment. All excited-state lifetimes exhibit a significant isotope effect (tau(D)2(O)/tau(H)2(O) approximately 2). Additionally, marked dynamical differences are found for two classes of water cluster anions, isomers I and II, previously assigned as clusters with internally solvated and surface-bound electrons, respectively. Isomer I clusters with n > or = 25 decay exclusively by internal conversion, with relaxation times that extrapolate linearly with 1/n toward an internal conversion lifetime of 50 fs in bulk water. Smaller isomer I clusters (13 < or = n < or = 25) decay through a combination of excited-state autodetachment and internal conversion. The relaxation of isomer II clusters shows no significant size dependence over the range of n = 60-100, with autodetachment an important decay channel following excitation of these clusters. Photoelectron angular distributions (PADs) were measured for isomer I and isomer II clusters. The large differences in dynamical trends, relaxation mechanisms, and PADs between large isomer I and isomer II clusters are consistent with their assignment to very different electron binding motifs.
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Affiliation(s)
- Arthur E Bragg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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211
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Van Doren JM, Kerr DM, Miller TM, Viggiano AA. Electron attachment and detachment, and the electron affinities of C5F5N and C5HF4N. J Chem Phys 2005; 123:114303. [PMID: 16392555 DOI: 10.1063/1.2032967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rate constants have been measured for electron attachment to C5F5N (297-433 K) and to 2, 3, 5, 6-C5HF4N (303 K) using a flowing-afterglow Langmuir-probe apparatus (at a He gas pressure of 133 Pa). In both cases only the parent anion was formed in the attachment process. The attachment rate constants measured at room temperature are 1.8 +/- 0.5 X 10(-7) and 7 +/- 3 X 10(-10) cm(-3) s(-1), respectively. Rate constants were also measured for thermal electron detachment from the parent anions of these molecules. For C5F5N- detachment is negligible at room temperature, but increases to 2530 +/- 890 s(-1) at 433 K. For 2, 3, 5, 6-C5HF4N-, the detachment rate at 303 K was 520 +/- 180 s(-1). The attachment/detachment equilibrium yielded experimental electron affinities EA(C5F5N)=0.70 +/- 0.05 eV and EA(2, 3, 5, 6-C5HF4N)=0.40 +/- 0.08 eV. Electronic structure calculations were carried out for these molecules and related C5HxF5-xN using density-functional theory and the G3(MP2)//B3LYP compound method. The EAs are found to decrease by 0.25 eV, on average, with each F substitution by H. The calculated EAs are in good agreement with the present experimental results.
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Affiliation(s)
- Jane M Van Doren
- Department of Chemistry, College of the Holy Cross, Worcester, MA 01610-2395, USA.
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212
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Hammer NI, Roscioli JR, Johnson MA, Myshakin EM, Jordan KD. Infrared Spectrum and Structural Assignment of the Water Trimer Anion. J Phys Chem A 2005; 109:11526-30. [PMID: 16354044 DOI: 10.1021/jp053769c] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bending vibrational spectrum of the perdeutero isotopomer of the water trimer anion has been measured and compared with spectra calculated using the MP2, CCSD, and Becke3LYP electronic structure methods. Due to its low electron binding energy (approximately 150 meV), only the OD bending region of the IR spectrum of (D2O)3(-) is accessible experimentally, with electron ejection dominating at higher photon energies. The calculated spectrum of the isomer having three water molecules arranged in a chain agrees best with the experimental spectrum. In the chain isomer, the excess electron is bound to the terminal water monomer with two dangling OH groups. This is consistent with the electron binding mechanism established previously for the (H2O)n(-) (n = 2, 4-6) anions.
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Affiliation(s)
- N I Hammer
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA
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213
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Turi L, Sheu WS, Rossky PJ. Characterization of excess electrons in water-cluster anions by quantum simulations. Science 2005; 309:914-7. [PMID: 16081731 DOI: 10.1126/science.1115808] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Water-cluster anions can serve as a bridge to understand the transition from gaseous species to the bulk hydrated electron. However, debate continues regarding how the excess electron is bound in (H2O)-n, as an interior, bulklike, or surface electronic state. To address the uncertainty, the properties of (H2O)-n clusters with 20 to 200 water molecules have been evaluated by mixed quantum-classical simulations. The theory reproduces every observed energetic, spectral, and structural trend with cluster size that is seen in experimental photoelectron and optical absorption spectra. More important, surface states and interior states each manifest a characteristic signature in the simulation data. The results strongly support assignment of surface-bound electronic states to the water-cluster anions in published experimental studies thus far.
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Affiliation(s)
- László Turi
- Eötvös Loránd University, Department of Physical Chemistry, Budapest 112, Post Office Box 32, H-1518, Hungary
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214
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Affiliation(s)
- Jacopo Tomasi
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
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215
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Diken EG, Headrick JM, Johnson MA. Photoelectron spectroscopy of the [glycine∙(H2O)1,2]− clusters: Sequential hydration shifts and observation of isomers. J Chem Phys 2005; 122:224317. [PMID: 15974678 DOI: 10.1063/1.1930833] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The electron binding energies of the small hydrated amino acid anions, [glycine x (H2O)(1,2)]-, are determined using photoelectron spectroscopy. The vertical electron detachment energies (VDEs) are found to increase by approximately 0.12 eV with each additional water molecule such that the higher electron binding isomer of the dihydrate is rather robust, with a VDE value of 0.33 eV. A weak binding isomer of the dihydrate is also recovered, however, with a VDE value (0.14 eV) lower than that of the monohydrate. Unlike the situation in the smaller (n < or = 13) water cluster anions, the [Gly x (H2O)(n > or = 6)]- clusters are observed to photodissociate via water monomer evaporation upon photoexcitation in the O-H stretching region. We discuss this observation in the context of the mechanism responsible for the previously observed [S. Xu, M. Nilles, and K. H. Bowen, Jr., J. Chem. Phys. 119, 10696 (2003)] sudden onset in the cluster formation at [Gly x (H2O)5]-.
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Affiliation(s)
- Eric G Diken
- Sterling Chemistry Laboratory, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, USA
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216
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Liu Y, Suess L, Dunning FB. Rydberg electron transfer to SF6: Product ion lifetimes. J Chem Phys 2005; 122:214313. [PMID: 15974744 DOI: 10.1063/1.1925276] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The lifetimes of SF6- ions produced by Rydberg electron transfer in K(np)SF6 collisions at high n, n greater or similar to 30, are examined using a Penning ion trap. The data point to the formation of ions with a range of lifetimes that extends from approximately 1 to greater or similar to 10 ms. Sizable numbers of ions remain in the trap even 40 ms after initial injection and at least part of this signal can be attributed to radiative stabilization. Measurements of free low-energy electron attachment to SF6 in the trap show that the product ions have lifetimes similar to those of SF6- ions formed by electron transfer in high-n collisions.
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Affiliation(s)
- Y Liu
- Department of Physics and Astronomy and the Rice Quantum Institute, MS 61 Rice University, 6100 Main Street, Houston, Texas 77005-1892, USA
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217
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Hammer NI, Compton RN, Adamowicz L, Stepanian SG. Isotope effects in dipole-bound anions of acetone. PHYSICAL REVIEW LETTERS 2005; 94:153004. [PMID: 15904140 DOI: 10.1103/physrevlett.94.153004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Indexed: 05/02/2023]
Abstract
Precision measurements using the Rydberg charge-exchange and electric field-detachment methods find that the dipole-bound electron affinity (EA) of acetone (C3H6O) is 55+/-10 mueV greater than for deuterated acetone (C3D6O). The result agrees well with a theoretical prediction obtained with high-level electronic-structure and anharmonic vibrational calculations. The dipole moments calculated for the vibrationally averaged structures of C3H6O and C3D6O show that the isotope effect (2% reduction) on the EA of acetone is mainly due to a slight reduction (0.5%) of the average dipole moment upon deuteration.
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Affiliation(s)
- Nathan I Hammer
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA
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218
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Sommerfeld T. Dipole-bound states as doorways in (dissociative) electron attachment. ACTA ACUST UNITED AC 2005. [DOI: 10.1088/1742-6596/4/1/036] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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219
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Affiliation(s)
- Kenneth D Jordan
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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220
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Hammer NI, Shin JW, Headrick JM, Diken EG, Roscioli JR, Weddle GH, Johnson MA. How do small water clusters bind an excess electron? Science 2004; 306:675-9. [PMID: 15375220 DOI: 10.1126/science.1102792] [Citation(s) in RCA: 234] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The arrangement of water molecules around a hydrated electron has eluded explanation for more than 40 years. Here we report sharp vibrational bands for small gas-phase water cluster anions, (H2O)(4-6)- and (D2O)(4-6)-. Analysis of these bands reveals a detailed picture of the diffuse electron-binding site. The electron is closely associated with a single water molecule attached to the supporting network through a double H-bond acceptor motif. The local OH stretching bands of this molecule are dramatically distorted in the pentamer and smaller clusters because the excited vibrational levels are strongly coupled to the electron continuum. The vibration-to-electronic energy transfer rates, as revealed by line shape analysis, are mode-specific and remarkably fast, with the symmetric stretching mode surviving for less than 10 vibrational periods [50 fs in (H2O)4-].
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Affiliation(s)
- Nathan I Hammer
- Sterling Chemistry Laboratory, Yale University, Post Office Box 208107, New Haven, CT 06520, USA
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221
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Sommerfeld T. Intramolecular Electron Transfer from Dipole-Bound to Valence Orbitals: Uracil and 5-Chlorouracil. J Phys Chem A 2004. [DOI: 10.1021/jp049082u] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas Sommerfeld
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
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222
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Sindelka M, Spirko V, Jungwirth P, Wang F, Mahalakshmi S, Jordan KD. Calculation of the photodetachment cross sections of the HCN- and HNC- dipole-bound anions as described by a one-electron Drude model. J Chem Phys 2004; 121:1824-9. [PMID: 15260733 DOI: 10.1063/1.1766296] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The Drude model for treating the interaction of excess electrons with polar molecules is extended to calculate continuum functions and to evaluate photodetachment cross sections. The approach is applied to calculate the cross sections for photodetachment of dipole-bound electrons from HCN(-) and HNC(-). In addition, an adiabatic model separating the angular and radial degrees of freedom of the excess electron is introduced and shown to account in a qualitative manner for the cross sections.
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Affiliation(s)
- M Sindelka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, and Center for Complex Molecular Systems and Biomolecules, Flemingovo nam. 2, 16610 Prague 6, Czech Republic
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223
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Li P, Bu Y, Ai H. Theoretical Determinations of Ionization Potential and Electron Affinity of Glycinamide Using Density Functional Theory. J Phys Chem A 2004. [DOI: 10.1021/jp035951o] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Ping Li
- Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China, and Department of Chemistry, Qufu Normal University, Qufu 273165, P. R. China
| | - Yuxiang Bu
- Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China, and Department of Chemistry, Qufu Normal University, Qufu 273165, P. R. China
| | - Hongqi Ai
- Institute of Theoretical Chemistry, Shandong University, Jinan 250100, P. R. China, and Department of Chemistry, Qufu Normal University, Qufu 273165, P. R. China
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Hammer NI, Hinde RJ, Compton RN, Diri K, Jordan KD, Radisic D, Stokes ST, Bowen KH. Dipole-bound anions of highly polar molecules: Ethylene carbonate and vinylene carbonate. J Chem Phys 2004; 120:685-90. [PMID: 15267903 DOI: 10.1063/1.1629669] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Results of experimental and theoretical studies of dipole-bound negative ions of the highly polar molecules ethylene carbonate (EC, C3H4O3, mu=5.35 D) and vinylene carbonate (VC, C3H2O3, mu=4.55 D) are presented. These negative ions are prepared in Rydberg electron transfer (RET) reactions in which rubidium (Rb) atoms, excited to ns or nd Rydberg states, collide with EC or VC molecules to produce EC- or VC- ions. In both cases ions are produced only when the Rb atoms are excited to states described by a relatively narrow range of effective principal quantum numbers, n*; the greatest yields of EC- and VC- are obtained for n*(max)=9.0+/-0.5 and 11.6+/-0.5, respectively. Charge transfer from low-lying Rydberg states of Rb is characteristic of a large excess electron binding energy (Eb) of the neutral parent; employing the previously derived empirical relationship Eb=23/n*(max)(2.8) eV, the electron binding energies are estimated to be 49+/-8 meV for EC and 24+/-3 meV for VC. Electron photodetachment studies of EC- show that the excess electron is bound by 49+/-5 meV, in excellent agreement with the RET results, lending credibility to the empirical relationship between Eb and n*(max). Vertical electron affinities for EC and VC are computed employing aug-cc-pVDZ atom-centered basis sets supplemented with a (5s5p) set of diffuse Gaussian primitives to support the dipole-bound electron; at the CCSD(T) level of theory the computed electron affinities are 40.9 and 20.1 meV for EC and VC, respectively.
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Affiliation(s)
- Nathan I Hammer
- Department of Chemistry, The University of Tennessee, Knoxville, Tennessee 37996, USA
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Svozil D, Jungwirth P, Havlas Z. Electron Binding to Nucleic Acid Bases. Experimental and Theoretical Studies. A Review. ACTA ACUST UNITED AC 2004. [DOI: 10.1135/cccc20041395] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An in-depth knowledge of an excess electron binding mechanism to DNA and RNA nucleobases is important for our understanding of radiation damage influence on the biological functions of nucleic acids, as well as for the possible use of DNA molecules as wires in molecular electronic circuits. The of anions created by electron attachment to individual nucleic acid bases is discussed in detail. The principles of the experimental and theoretical approaches to the description of these anions are outlined, and the available results concerning valence- and dipole-bound anions of nucleic acid bases are reviewed. A review with 167 references.
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Wang F, Jordan KD. Parallel-tempering Monte Carlo simulations of the finite temperature behavior of (H2O)6−. J Chem Phys 2003. [DOI: 10.1063/1.1624597] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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