Richard J Plowright

University of Nottingham, Nottingham, ENG, United Kingdom

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Publications (17)40.71 Total impact

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    ABSTRACT: Ab initio calculations were employed to determine the geometry (MP2 level), and dissociation energies [MP2 and RCCSD(T) levels], of the MIIa+/RG2 species, where MIIa is a Group 2 metal, Be or Mg, and RG is a rare gas (He-Rn). We compare the results with similar calculations on MIa+-RG2, where MIa is a Group 1 metal, Li or Na. It is found that the complexes involving the Group 1 metals are linear (or quasilinear), while those involving the Group 2 metals are bent. We discuss these results in terms of hybridization and the various interactions in these species. Trends in binding energies, De, bond lengths and bond angles are discussed. We compare the energy required for the removal of a single RG atom from M+/RG2 (De2) with that of the dissociation energy of M+/RG (De1); some complexes have De2 > De1, some have De2 < De1, and some have the values about the same. We also present relaxed angular cuts through a selection of potential energy surfaces. The trends observed in the geometries and binding energies of these complexes are discussed. Mulliken, natural population and atoms-in-molecules population analyses are performed, and it is concluded that the AIM method is the most reliable, giving results that are in line with molecular orbital diagrams and contour plots; unphysical amounts of charge transfer are suggested by the Mulliken and natural population approaches.
    The Journal of Physical Chemistry A 09/2013; · 2.77 Impact Factor
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    ABSTRACT: Metal cation rare gas complexes provide an expectedly simple system with which to investigate intermolecular interactions. Despite this, we have previously found the M+-RG (M = alkaline earth metal) complexes to very complicated systems, with the complexes of the heavier rare gases displaying surprisingly large degrees of chemical character. Here we extend these studies by examining the nature of these interactions with increasing degrees of solvation through investigating the M+-RG_2 complexes using high level {ab initio} techniques. Intriguing trends in the geometries and dissociation energies of these complexes have been observed and are rationalized. A. M. Gardner, C. D. Withers, J. B. Graneek, T. G. Wright, L. A. Viehland and W. H. Breckenridge, J. Phys. Chem. A, 2000, 114, 7631. A. M. Gardner, C. D. Withers, T. G. Wright, K. I. Kaplan, C. Y. N. Chapman, L. A. Viehland, E. P. F. Lee and W. H. Breckenridge, J. Chem. Phys., 2010, 132, 054302. M. F. McGuirk, L. A. Viehland, E. P. F. Lee, W. H. Breckenridge, C. D. Withers, A. M. Gardner, R. J. Plowright and T. G. Wright, J. Chem. Phys., 2009, 130, 194305.
    06/2012;
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    ABSTRACT: Electronic spectra of the Au-Ne complex have been recorded for the first time in the vicinity of the atomic Au 6p ← 6s transition. A structured spectrum was observed near the Au ^2P3/2 ← ^2S1/2 transition, however, the complex spectrum expected near the Au ^2P1/2 ← ^2S1/2 transition was not observed. This is rationalized using high level ab intio calculations. R. J. Plowright, A. M. Gardner, C. D. Withers, T. G. Wright, M. D. Morse and W. H. Breckenridge, J. Phys. Chem. A, 114, 3103, (2010)
    06/2011;
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    ABSTRACT: The photodissociation dynamics of Au-Xe leading to Xe(+) formation via the Ξ(1∕2)-X(2)Σ(+) (v('), 0) band system (41 500-41 800 cm(-1)) have been investigated by velocity map imaging. Five product channels have been indentified, which can be assigned to photoinduced charge transfer followed by photodissociation in either the neutral or the [Au-Xe](+) species. For the neutral species, charge transfer occurs via a superexcited Rydberg state prior to dissociative ionization, while single-photon excitation of the gold atom in Au(+)-Xe accesses an (Au(+))∗-Xe excited state that couples to a dissociative continuum in Au-Xe(+). Mechanisms by which charge transfer occurs are proposed, and branching ratios for Xe(+) formation via the superexcited Rydberg state are reported. The bond dissociation energy for the first excited state of Au(+)-Xe is determined to be ∼9720 ± 110 cm(-1).
    The Journal of Chemical Physics 03/2011; 134(9):094311. · 3.12 Impact Factor
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    ABSTRACT: The ultraviolet photodissociation dynamics of the gold-rare gas atom van der Waals complexes (Au-RG, RG = Ar, Kr, and Xe) have been studied by velocity map imaging. Photofragmentation of Au-Ar and Au-Kr at several wavelengths permits extrapolation to zero of the total kinetic energy release (TKER) spectra as monitored in the Au((2)P(3/2)(o)[5d(10)6p]) fragment channel, facilitating the determination of ground state dissociation energies of D(0)(")(Au-Ar) = 149+/-13 cm(-1) and D(0)(")(Au-Kr) = 240+/-19 cm(-1), respectively. In the same spectral region, transitions to vibrational levels of an Omega(') = 1/2 state of the Au-Xe complex result in predissociation to the lower Au((2)P(1/2)(o)[5d(10)6p])+Xe((1)S(0)[5p(6)]) fragment channel for which TKER extrapolation yields a value of D(0)(")(Au-Xe) = 636+/-27 cm(-1). Asymmetric line shapes for transitions to the v(') = 14 level of this state indicate coupling to the Au((2)P(3/2)(o)[5d(10)6p])+Xe((1)S(0)[5p(6)]) continuum, which allows us to refine this value to D(0)(")(Au-Xe) = 607+/-5 cm(-1). The dissociation dynamics of this vibrational level have been studied at the level of individual isotopologues by fitting the observed excitation spectra to Fano profiles. These fits reveal a remarkable variation in the predissociation dynamics for different Au-Xe isotopologues. For Au-Ar and Au-Xe, the determined ground state dissociation energies are in good agreement with recent theoretical calculations; the agreement of the Au-Kr value with theory is less satisfactory.
    The Journal of Chemical Physics 06/2010; 132(21):214303. · 3.12 Impact Factor
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    ABSTRACT: We present high level ab initio potential energy curves for the X 2Σ+ electronic states of the CM–RG complexes; where CM is a coinage metal, CM = Cu, Ag and Au and RG is a rare gas, RG = He–Rn. These potentials are calculated over a range of internuclear separations, R, and the energy at each point is corrected for basis set superposition error and extrapolated to the basis set limit. Spectroscopic constants are determined from the potentials so obtained and are compared to available experimental data. The impact of core-valence correlation to the overall interactions within the complexes involving the lighter RG atoms is also considered. We find that there is a surprising continuous decrease in Re in these species from CM-He to CM-Rn and show that this is likely due to a combination of sp hybridization and small amounts of charge transfer.
    The Journal of Chemical Physics 05/2010; 132(18):184301-184301-9. · 3.12 Impact Factor
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    ABSTRACT: We report electronic spectra of the Au-Ne complex, obtained in the vicinity of the Au atomic 6p <-- 6s transition. The structured spectrum found near the (2)P(3/2) <-- (2)S(1/2) transition is analyzed. We also explain the nonobservance of a spectrum close to the 6(2)P(1/2) state, using the results of high level ab initio calculations and insight from previous work on other Au-RG complexes (where RG = Ar, Kr, and Xe). Basis set extrapolated RCCSD(T) potential energy curves are also presented for the X(2)Sigma(+) ground state of Au-Ne, and the derived D(e) value is compared to experimental values. We then present an overview of trends through the Au-RG series: included in this are calculations on the X states of Au-He and Au-Rn, as well as for Au(+)-He. We also report further calculations on the states which arise from the interaction of Au(6(2)P(J)) with the rare gas atoms and include a Franck-Condon simulation of the D(2)Pi(3/2) <-- X(2)Sigma(1/2)(+) transition for Au-Ar. Trends in the spectroscopy across this series are summarized, and the Hund's case (a)/(c) character discussed.
    The Journal of Physical Chemistry A 03/2010; 114(9):3103-13. · 2.77 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 10/2009; 40(43).
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    ABSTRACT: Optimized geometries and vibrational frequencies were calculated for Mg+-X and [X-Mg-Y]+ complexes (X, Y = H2O, N2, CO2, O2, and O), required for understanding the chemistry of magnesium in the upper atmosphere. B3LYP optimizations were performed employing 6-311+G(2d,p) basis sets. In several cases a number of different orientations were investigated in order to determine the geometries of lowest energy, and in cases involving O and O2, different spin states also had to be considered. In contrast to the corresponding Ca+-containing complexes, the diligated Mg+ ions have the two ligands approaching from the same side. In order to establish accurate energetics, up to RCCSD(T) single-point energy calculations were also employed, using quadruple-zeta basis sets. Accurate dissociation energies for the Mg+-X and [X-Mg-Y]+ species were derived and discussed. Comparison with available experimental results was made where possible.
    The Journal of Physical Chemistry A 08/2009; 113(33):9354-64. · 2.77 Impact Factor
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    ABSTRACT: We present high-level ab initio potential energy curves for barium cations and dications interacting with RG atoms (RG = rare gas). These potentials are employed to derive spectroscopic parameters for the Ba+–RG and Ba2+–RG complexes, and also to derive the transport coefficients for Ba+ and Ba2+ moving through a bath of the rare gas. The results are compared to the limited experimental data, which generally show reasonable agreement. We identify a large change in binding energy going from Ba+–He and Ba+–Ne to Ba+–Ar, which is not present in Ba2+–RG, and show that this is due to significant dispersion interactions in Ba+–RG.
    The Journal of Chemical Physics 05/2009; 130(19):194305-194305-9. · 3.12 Impact Factor
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    ABSTRACT: We report electronic spectra of the Au-Xe complex for the first time. The transitions are recorded in the vicinity of the Au atomic 6p<-- 6s transitions. Structured spectra are found close to both the 6(2)P(1/2) and 6(2)P(3/2) states. The former is assigned as a (2)Pi(1/2) state in line with previous work on Au-Ar and Au-Kr; the possible assignment of the second spectrum is discussed. In addition, a large basis set extrapolated RCCSD(T) potential energy curve for the ground state, X(2)Sigma(+), is presented and derived spectroscopic parameters reported. More qualitative calculations are presented for electronically-excited states which arise from the Au(5(2)D) + Xe and Au(6(2)P) + Xe asymptotes, as well as some higher-lying states. The ab initio results are employed in the assignment of the reported spectra.
    Physical Chemistry Chemical Physics 04/2009; 11(10):1539-50. · 3.83 Impact Factor
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    ABSTRACT: We report electronic absorption spectra, recorded using one- and two-color resonance-enhanced multiphoton ionization spectroscopy, of the Au-Kr complex. The transition is localized on the gold atom, and corresponds to a 6p<--6s atomic excitation; we observe transitions to the D (2)Pi(1/2) and D (2)Pi(3/2) spin-orbit states. In addition, we report the results of ab initio calculations, which consider electronic states arising from the 6 (2)S, 5 (2)D, and 6 (2)P atomic energy levels of Au. Further, we also report an accurate value for the dissociation energy of the ground state of Au-Kr, based on basis set extrapolated RCCSD(T) calculations. The experimental results are discussed in the light of the theoretical ones.
    The Journal of Chemical Physics 11/2008; 129(15):154315. · 3.12 Impact Factor
  • Richard J Plowright, Timothy G Wright, John M C Plane
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    ABSTRACT: Optimized geometries and vibrational frequencies are calculated for Ca(+)-X and Y-Ca(+)-X complexes (X, Y = H2O, N2, CO2, O2, and O), required for understanding the chemistry of calcium in the upper atmosphere. Both MP2 and B3LYP optimizations were performed employing 6-311+G(2d,p) basis sets. In some cases a number of different orientations had to be investigated in order to determine the one of lowest energy, and in cases involving O and O2, different spin states also had to be considered. In order to establish accurate energetics, RCCSD(T) single-point energy calculations were also employed, using aug-cc-pVQZ basis sets. Accurate dissociation energies for the Ca(+)-X and X-Ca(+)-Y species are derived and discussed. Comparison with available experimental results is made where possible.
    The Journal of Physical Chemistry A 08/2008; 112(29):6550-7. · 2.77 Impact Factor
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    ABSTRACT: We present the results of ab initio calculations, which include spin-orbit coupling, to support our recently-proposed interpretation of (1 + 1) resonance-enhanced multiphoton ionization (REMPI) spectroscopy of the Au–Ar complex. Mixing between the 2Σ1/2+ and 2Π1/2 (···6p1) states leads to a dramatic decrease of the well-depth of the latter, as well as a perturbation in the outer wall.
    Chemical Physics Letters 01/2008; 459:70-72. · 2.15 Impact Factor
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    ABSTRACT: The Au-Ar complex is reinvestigated employing resonance-enhanced multiphoton ionization spectroscopy. Spectra are reported, corresponding to the atomic transition Au(6p<--6s). This electronic excitation yields (2)Pi and (2)Sigma(+) states of Au-Ar, which interact under the influence of spin-orbit coupling. The spectra are consistent with strong sigma-pi mixing induced by the large spin-orbit coupling of Au, leading to strong interaction of the two Omega=12 states, which arise from the Ar((1)S(0))+Au((2)P(12,32)) asymptotes, and the consequent formation of a "shelf" on the outer wall of the lowest Omega=12 state. In addition, high-level ab initio calculations are reported on the ground electronic state, X (2)Sigma(+), including extrapolation to the basis set limit.
    The Journal of Chemical Physics 11/2007; 127(20):204308. · 3.12 Impact Factor
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    ABSTRACT: We investigate the A∼2Σ+ state of NO–Ne by high-level ab initio methods, and by (1 + 1) resonance-enhanced multiphoton ionization spectroscopy (REMPI). Despite being able to obtain high-quality spectra of NO–Ar, NO–Kr and NO–Xe, no spectrum of NO–Ne was observed. It is shown that this state is very weakly bound; and that the overlap between the zero-point vibrational energy level in the X∼2Π state, and the bound levels of the A∼2Σ+ state is very small: hence the Franck–Condon factors are close to zero. The location of the Ne atom outside the 3s Rydberg orbital is the cause of the observations.
    Chemical Physics Letters 06/2007; 441(s 4–6):181–186. · 2.15 Impact Factor
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    John M C Plane, Richard J Plowright, Timothy G Wright
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    ABSTRACT: High-level ab initio calculations were carried out on a series of K+.X cluster ions (X = O, O2, N2, CO2, H2O) and X.K+.Y ions. Rice-Ramsberger-Kassel-Markus theory was then used to estimate the rate coefficients for a series of recombination and ligand-switching reactions that govern the ion-molecule chemistry of K+ in the upper mesosphere and lower thermosphere. These rate coefficients were then included in an atmospheric model of potassium chemistry. The important result is that K+ forms weakly bound clusters with N2, O2, and O (the major atmospheric species), with binding energies between 10 and 22 kJ mol(-1). Even under atmospheric conditions (200 K and 10(-3) Torr), these cluster dissociate in less than 1 s. This prevents the formation by ligand-switching of the more stable CO2 and H2O clusters, which could then undergo dissociative recombination with electrons to produce K. The result is that K+ ions have a much longer lifetime against neutralization in the upper atmosphere than other metallic ions such as Na+ and Fe+.
    The Journal of Physical Chemistry A 04/2006; 110(9):3093-100. · 2.77 Impact Factor