Theory for the electron affinity of clusters of rare gas atoms and polar molecules

Stampfli, P.

doi:10.1016/0370-1573(94)00089-l

Cited by 70 publications

(55 citation statements)

References 94 publications

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“…For the cluster radius we choose [5,6] R N R 0 1:5N 1=3 , R 0 3 a:u: V 0 in the CO 2 cluster can be estimated from comparison of scattering lengths, polarizabilities, and electron excess energies for Ar, Kr, Xe, and CO 2 [18]. We obtained V 0 ÿ0:65 eV and a 0:85 eV.…”

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“…where Ur is the effective e-CO 2 interaction, R N is the effective radius of the cluster, V 0 is the energy of the excess electron in the bulk, and a is a parameter which can be obtained from the calculation of the electron energy in the cluster center by the continuum-medium approximation [18]. For the cluster radius we choose [5,6] R N R 0 1:5N 1=3 , R 0 3 a:u: V 0 in the CO 2 cluster can be estimated from comparison of scattering lengths, polarizabilities, and electron excess energies for Ar, Kr, Xe, and CO 2 [18].…”

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Theory of Electron Attachment toCO2Clusters

Fabrikant

Hotop

2005

Phys. Rev. Lett.

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Theory of Electron Attachment toCO2Clusters

Fabrikant

Hotop

2005

Phys. Rev. Lett.

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“…The diagonal blocks of H are a sum of the repulsion between the ionized atom and neutral atoms, the Van der Waals interaction between the neutral atoms and the polarization energy of the cluster [6]. The repulsion between an ionized atom and a neutral atom is obtained from an average of the energies of the dimer ion, similarly as in equation (3).…”

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Fragmentation of large ionized clusters of rare gas atoms

Stampfli

1997

Z Phys D - Atoms, Molecules and Clusters

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Molecular dynamics is used to examine the fragmentation of clusters of rare gas atoms after ionization. The cohesive energy is given by a quantum mechanical model with a delocalized hole. Very small clusters dissociate entirely into single atoms and a positively charged dimer. Larger clusters (e.g. Ne 13 , Xe 13 and Ne 55 ) first eject rapid atoms, then thermalize and evaporate further atoms, which strongly decreases their size. Very large clusters (e.g. Xe 55 ) are only heated up after ionization and do not loose atoms. Thus the peaks in mass spectra do not show the atomic shell structure of neutral clusters up to rather large cluster sizes. Instead the stability of ionized clusters is reflected. PACS: 36.40.Qv; 36.40.WaNeutral clusters of rare gas atoms have an atomic shell structure, which causes magic numbers at shell closings [1,2]. However, these magic numbers may not be seen as peaks in the mass spectra if the clusters fragment after ionization. This is examined in the present paper.Note that an ionized rare gas atom has an open electronic shell like a halogen. Thus strong covalent forces arise in ionized clusters and a tightly bound subcluster of 2 to 4 atoms, which share the positive charge, is formed inside the cluster. The other atoms are only loosely bound by Van der Waals and polarization forces. The equilibrium geometries of ionized clusters and of neutral clusters then differ strongly, such that the vertical ionization of a neutral cluster gives a vibrationally highly excited cluster, which then might fragment.In the present work I first used constant temperature molecular dynamics (T = 5 K for Neon and T = 50 K for Xenon clusters) and a Lennard Jones potential to generate structures of neutral clusters at a given size [3]. Assuming vertical ionization by photon absorption or electron impact, these structures are then used as initial configurations for a constant energy molecular dynamics simulation of ionized clusters, which yields the fragmentation. Thus cluster size distributions at various times t after ionization are obtained.For the cohesive energy of ionized clusters I use a quantum mechanical dimer-in-molecules (DIM) model [4]. The hole can be distributed on the valence p-orbitals of all atoms of the cluster. This is determined by a single-particle wavefunction, which is a vector ψ = a 1px , a 1py , a 1pz , a 2px , a 2py , a 2pz , a 3px , . . . .(1)The amplitudes a ipµ determine the probability P i,µ = |a ipµ | 2 that the hole can be found in a p µ -orbital of an atom i. The energy E is obtained from the Schrödinger equation.The off-diagonal blocks of the Hamiltonian H cause a hopping of the hole between different atoms. These matrix elements are obtained from ab-initio calculations of the energies E Πg,u and E Σu,g of the pi and sigma bonding and antibonding states of the ionized dimer [5],where d ij = |R i − R j | is the distance between the atoms with positons R i and R j and n ij = (R i − R j )/d ij is the unit vector in bond-direction. The diagonal blocks of H are a sum of the repulsio...

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“…Because of its chemical inertness and its relatively high critical temperature and low critical pressure, xenon is a popular supercritical solvent for probing density effects on electron mobility in highly polarizable fluids (see, for example, [1][2][3][4][5][6]) and for investigating pulse radiolysis reaction kinetics (see, for example, [6][7][8]). While xenon critical effects on electron mobility have been explored [9,10], an investigation of these effects on the quasi-free electron energy in xenon has not been performed.…”

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Energy of the quasi-free electron in xenon

Shi¹,

Li²,

Evans³

et al. 2006

Chemical Physics Letters

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Field ionization of trimethylamine and of N,N-dimethylaniline doped into xenon is presented as a function of xenon number density up to the density of the triple point liquid, both at noncritical temperatures and along the critical isotherm. These data exhibit a decrease in the xenon induced shift of the dopant ionization energy near the xenon critical point. The energy of the quasi-free electron, arising from dopant field ionization, in xenon is calculated within a local Wigner-Seitz model to within ±0.3% of experiment at noncritical temperatures and for the critical isotherm.

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Theory for the electron affinity of clusters of rare gas atoms and polar molecules

Cited by 70 publications

References 94 publications

Theory of Electron Attachment toCO2Clusters

Theory of Electron Attachment toCO2Clusters

Fragmentation of large ionized clusters of rare gas atoms

Energy of the quasi-free electron in xenon

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