The structure of mixed nitrogen-argon clusters (original) (raw)
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Structures of mixed argon-nitrogen clusters
The Journal of Chemical Physics, 2012
The structures of mixed argon-nitrogen clusters of different compositions are investigated by analyzing core level shifts and relative intensities of surface and bulk sites in the Ar 2p 3/2 regime in soft Xray photoelectron spectroscopy. These structures are confirmed by core level shift calculations taking induced dipole interactions into account, in which several model structures of the mixed clusters are considered by Monte Carlo simulations. These results suggest that the mixed argon-nitrogen clusters show partial core-shell structures, where an argon core is partially covered by nitrogen molecules.
Structural motifs and stability of small argon–nitrogen clusters
The Journal of Chemical Physics, 2003
The molecular dynamics ͑MD͒ simulation method is used to study Ar m (N 2 ) n clusters. Using realistic pair potentials for the argon-argon, nitrogen-nitrogen, and argon-nitrogen interactions, the structures and thermodynamics of these clusters are investigated. The initial focus of the study is the series of thirteen particle clusters of Ar m (N 2 ) 13Ϫm (0рmр13). These icosahedral argon-nitrogen clusters display systematic changes in energetics when argon is substituted by nitrogen in the central position. The relative stability of argon-centered clusters over nitrogen-centered clusters is further investigated by defining and calculating a ''species-centric'' order parameter which can be monitored during a MD simulation. These results are interpreted in terms of frustration effects due to anisotropy in the N 2 -N 2 and N 2 -Ar potentials. The consequences of these observations for cluster stability and for dynamical behavior, such as melting and evaporation, are investigated. The dynamical studies of larger clusters reveal that the mixed clusters evolve towards a structure with an argon core coated by a nitrogen shell.
Bulletin of the American Physical Society, 2006
ME 04469-5706-We perform direct MD simulations of the formation of mixed Xe n Ar m clusters (500<n+m<3000) in a supersonic beam as a function of initial beam conditions. We then model the 4d 5/2 (Xe) and 2p 3/2 (Ar) core hole photoelectron spectra of these clusters and compare them to the experimental spectra of Tchaplyguine et al [1]. The predicted spectra are calculated as the sum of final state energy shifts of the ionized atoms (within the cluster) relative to the isolated gas phase ion using a self-consistent polarization formalism. We use the results of our earlier calculations on pure argon and xenon clusters [2] to determine the appropriate inelastic mean free path value for the signal electrons leaving the mixed clusters. These results allow us to gain a refined understanding of the size, stoichiometry, and core/shell structure of these mixed clusters. [1] M. Tchaplyguine, et al,
Theoretical modeling of ionization energies of argon clusters: Nuclear delocalization effects
J. Chem. Phys. 134(22), 224310 , 2011
Temperature dependence of vertical ionization energies is modeled for small argon clusters (N ⩽ 13) using classical parallel-tempering Monte Carlo methods and extended interaction models based on the diatomics-in-molecules approach. Quantum effects at the zero temperature are also discussed in terms of zero-point nuclear vibrations, either at the harmonic approximation level or at the fully anharmonic level using the diffusionMonte Carlo calculations. Both approaches lead to a considerable improvement of the theoretical predictions of argon clusters ionization energies and represent a realistic way of modeling of ionization energies for weakly bound and floppy complexes in general. A thorough comparison with a recent electron-impact experiment [O. Echt et al., J. Chem. Phys.123, 084313 (2005)] is presented and a novel interpretation of the experimental data is proposed.
Structures and energetics of CO2–Arn clusters (n = 1–21) based on a non-rigid potential model
Canadian Journal of Chemistry, 2007
Energetics and possible stable structures of CO2–Arn (n = 1–21) clusters are investigated by performing molecular-dynamics simulations. The pairwise-additive approximation is tested to construct the potential energy function for describing the non-rigid particle interactions in the system. A potential model by Pariseau et al. (Journal of Chemical Physics, Vol. 42, p. 2335, 1965) is used for the internal motion of the CO2 molecule and the Billing form potential (Chemical Physics, Vol. 185, p. 199, 1994) is used for all other pair interactions. The stable configurations are determined for the ground state of CO2–Arn clusters, and the growing pattern process of the clusters is determined via rearrangement collisions. Ar atoms tend to surround the CO2 molecule, and the clusters prefer to form three-dimensional compact structures. Obtained structures and energetics are in quantitative agreement with previous results (Journal of Chemical Physics, Vol. 109, p. 1343, 1998) that have used sp...
Electron impact ionization efficiency curves of argon clusters and argon/methanol heteroclusters
The Journal of Physical Chemistry, 1992
The study of van der Waals clusters is an area of growing interest and is being widely studied for a number of reasons. The measurement of the ionization efficiency (IE) curves have yielded a wealth of information by enabling ionization and appearance energies of ions to be determined which are essential for the calculation of thermochemical data. In the case of van der Waals clusters, the measurement of IE curves enables one to determine the qualitative trends in the ionization potentials as a function of cluster size. In addition IE curves have also offered valuable insight into ionization related processes occurring in clusters. This paper will cover some of the more recent studies of Penning ionization, exciton induced decay and Coulomb explosion in van der Waals clusters through the use of electron impact IE curves.
Journal of Physical Chemistry A, 1997
An experimental spectroscopic study of the van der Waals aniline-Ar n clusters (n ) 1-6) has been achieved via resonant two-photon two-color ionization, whose results improve the accuracy of the previously reported spectra and complete them by the observation of further structure in the spectra of well-defined structural isomers. These experimental results have been analyzed in detail in relation with molecular dynamics simulations including minimum energy structures calculations, direct spectral simulations, and isomerization dynamics. Two potential energy surfaces, in both the ground S 0 and the electronically excited S 1 states, have been built in order to recover the main experimental observables. They permit the site specific electronic shift additivity rule to be confirmed by the semiclassical spectral simulations and a global picture of the solvation phenomena in this aromatic-rare gas atom system to be provided. In particular, careful examination of the isomerization dynamics helps the general understanding of the structural behavior of these microsolvent clusters.
Stability and the structures of Nitrogen clusters N10
2004
The structures and stability of nitrogen cluster N 10 were studied using DFT and MP2 methods. Eleven minima were optimized and characterized by both B3LYP/6-31G Ã and MP2/6-31G Ã harmonic vibrational frequency calculations. The stability was studied in terms of the barriers of isomerization and dissociation reactions on the potential energy surface (PES) of nitrogen cluster N 10 . The low barriers show that nitrogen clusters N 10 studied in this paper are not stable enough to be used as high-energy density-materials (HEDMs).
A theoretical study of the nitrogen clusters formed from the ions N, N, and N
The Journal of Chemical …, 2001
Exotic atoms and molecules; macromolecules; clusters. Atomic and molecular clusters. Reactivity of clusters. Physical chemistry and chemical physics . Specific chemical reactions; reaction mechanisms. Association, addition, insertion, cluster formation. Electronic structure of ...
Structure and dynamics of small protonated rare-gas clusters using quantum and classical methods
Computer Physics Communications, 2002
The possible structures of small He and Ar clusters containing H + as ionic impurity are shown to be amenable to a detailed analysis of their structures and of the dynamical evolution by means of Ab Initio Molecular Dynamics (AIMD) treatments as well as by quantum treatments via Diffusion Monte Carlo (DMC) approaches. The two methods are briefly reviewed and their computational results are analyzed.