Thrust area: Novel Nanostructures Based on LowDimensional Semiconductor Systems'

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Thrust area Novel Nanostructures Based on
Low-Dimensional Semiconductor Systems.

• Frank Hagelberg, Principal Investigator
• William A. Lester, Jr, Co-Principal Investigator
• Jian-Ge Zhou, Research Associate

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• I. Main research topics
• - Fullerene cages with endohedral metal
  cluster
• impurities,
• - Polyhedral Oligomeric Silsesquioxane
  (POSS)
• clusters
• - Multiligated metal cations,
• - Electron impact ionization phenomena,
• - Nonadiabatic quantum dynamics
• II. Education related activities
• III. Publications and presentations

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Nontraditional Fullerenes enclosing metal atom
clusters.
- Three fused pentagons in the C68 cage
Violation of the Isolated Pentagon Rule
(IPR). - Strong gain of stability upon
incorporation of NSc3 in the C68 cage
Sc3N_at_C68
Use of Fullerenes enclosing metal atom clusters
as Novel Magnetic Resonance Imaging contrast
agents ?
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Fullerenes with incorporated Helium Clusters

• NMR studies on noble gas atoms enclosed in
  fullerene shells
• ( M. S. Syamala et al., JACS 124, 6216, 2002 ).
• Hen encapsulated fullerenes of extraterestial
  detected in geological sediments
• ( L. Becker et al., Science 291 1530 2001 ).

Hen configurations in fullerene cages?
He2_at_C60 ( D2d)
He_at_He20_at_C60 (Ih)
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Structural studies of Polyhedral Oligomeric
Silsesquioxane (POSS) cages
Geometry optimizations have been performed on
Si8O12R8 with R H, CH3, using a Density
Functional Theory (DFT) procedure.
Si8O12 (CH3)8
Si8O12H8
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Study of the geometry, stability and electronic
structure of POSS monomers with alkali atom
impurities.
POSS monomers with endohedral alkali
impurities. Impurities Li, Na, K. Matrix
Spherosiloxane.
Na_at_Si8O12H8
Li_at_Si8O12H8
Change of POSS cage symmetry from Oh to D2d upon
replacement of Na as endohedral impurity by Li.
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Interaction of POSS monomers and analogous
systems with atomic impurities
From experimental ion mobility studies1 Na
adopts an exohedral position
Comparison between Si8O12H8 with endohedral and
with exohedral alkali impurities.
Example A Li. ? Ee (Li_at_Si8O12H8) 1.2
eV ? Ee (Li Si8O12H8) 2.2 eV

• Ee Energy released upon encapsulation/
• attachment of impurity atom.

The exohedral isomer of A X8O12H8 is found more
stable than the endohedral one for A Li, Na,
K, and X C, Si. Halogen doped systems A-
X8O12H8 (A F, Cl, Br) prefer endohedral
geometries throughout.
1J.Gidden, Int.J.Mass Spec. 222, 63 (2002)
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Theory of multiligated metal cations

• Study of multiligated cations motivated by in
  interest in
• Solvation mechanisms of metal cations
• Metal ion coordination in varying environments
• Structural transitions in molecular clusters.
• Detection of tricationic metal atoms ligated with
  dimethylsulfoxide (DMSO) by electrospray
  ionization mass spectrometry (A. Shvartsburg,
  J.Am.Chem.Soc. 124, 12343 (2002)).

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• Investigation of M3 (DMSO)N with M Al, Sc and
  N ? 5.
• NMIN Minimal number of ligands L for which
  M3LN is (meta)stable.
• NCRIT Critical number of ligands such that
  M3LN disintegrates without dissociative charge
  transfer.
• NMIN (Al3DMSON) 2
• Sc3DMSO is metastable with activation barrier of
  3.2 eV.

Sc3 DMSO
Sc3 (DMSO)5
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Electron impact ionization phenomena The decay
of metastable rare gas dimer ions Rg2 (Rg Ne,
Ar).

• T. Maerk, P. Scheier, University of Innsbruck,
  Austria
• First observation of competing decay modes in
  Ne2.
• The reaction Ne2 II(1/2)u ? Ne Ne proceeds
  through
• Radiative dipolar transitions,
• B. Nonradiative transitions into the Ne2
  I(3/2)u continuum by predissociation.

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Nonadiabatic quantum dynamics

• Electron Nuclear Dynamics (END) Theory1
  Inclusion of electron dynamics.
• Relevance for processes involving
• - fast nuclear motion,
• - vibronic
  interactions between electrons and nuclei.
• Interpretation of the dynamic wave function ?dyn
  in terms of static configurations2.
• Understanding of dynamic wave function ?dyn in
  terms of ground state, excited states?
• Projection of ?dyn on an electronic basis (?0,
  ?k.) adiabatically transported along the nuclear
  trajectories,
• where
• ?0 Ground state determinant
• ?k Excited determinants (single substitutions,
  double substitutions)
• Expansion of ?dyn in the configuration basis
  (?0,.. ?k..).
• 1 E. Deumens, A. Diz, R. Longo, Y. Öhrn, Rev.
  Mod. Phys. 66, 3 917 (1994),
• 2 F.Hagelberg, E.Deumens, Phys. Rev. A 65, 52505
  (2002).

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Group members
Undergraduate student Kendrick Walker High
school student Jessica Blundell
Research Associates Dr. Jian-Ge Zhou Dr. Jianhua
Wu Dr. Sung Soo Park Graduate Student Yashesh
Pandya
Student research related to the theory of small
silicon clusters with metal atom impurities and
to multiligated cations.
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Publications 04/2003 04/2004

• -A Density-functional study on the structures,
  stabilities and dissociation pathways
• of Sc3(DMSO)n complexes (n1-6).
• C. Xiao, F. Hagelberg, A. M. El-Nahas,
  J.Phys.Chem., in press
• Theoretical study on the structures and
  dissociation channels of metal dications
• solvated by acetonitrile ligands.
• C. Xiao, K. Walker, F. Hagelberg, A. M.
  El-Nahas, Int. J. Mass Spec., in press.
• - Silicon clusters doped with an Yttrium metal
  atom.
• C. Xiao, J. Blundell, F. Hagelberg W. A. Lester,
  Jr., Int. J. Quant. Chem. 96,
• 461 (2004).
• Probing electronic states of Ne2 and Ar2 by
  measuring kinetic energy release
• distributions.
• J. Fedor, R. Parajuli, S. Matt-Leubner, O. Echt,
  F. Hagelberg, K. Gluch, M. Probst,
• P. Scheier, T. D. Maerk., Phys. Rev. Lett. 91,
  133401 (2003).
• - The Formation of New Silicon Cages A
  Semiempirical Theoretical Investigation.
• J. G. Han, Z. Y. Ren, Z. F. Chen, L. S. Sheng,
  Y. W. Zhang, J. A. Morales
• and F.Hagelberg, J. Mol. Struct. (Theochem) 625,
  47 (2003)
• - Energetics and dynamics of decaying cluster
  ions.
• K. Gluch, J. Fedor, S. Matt-Leubner, R.
  Parajuli, C. Mair, A. Stamatovic, O. Echt,
• C.Lifshitz, J. Harvey, F. Hagelberg, Z. Herman,
  M. Probst, P. Scheier, T. D. Maerk,

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Presentations 04/2003 04/2004

• Conference presentations.
• Nonadiabatic Evolution of Electronic States by
  Electron Nuclear Dynamics Theory Application to
  Atom-Molecule Scattering Problems.
• Talk, presented at the March Meeting of the
  American Physical Society 2004, Montreal, CA,
  3/25/2004.
• Non-classical Fullerene Cages Enclosing Metal
  Atom Clusters.
• Talk, presented at the March Meeting of the
  American Physical Society 2004, Montreal, CA,
  3/24/2004.
• Nonadiabatic Effects in Atom-Molecule
  Scattering by Electron Nuclear Dynamics Theory.
• Poster, presented at the 44th Sanibel Symposium,
  St. Augustine, FL, 3/2/2004.
• Substitutional and Endohedral Structures Based
  on Polyhedral Oligomeric Silsesquioxane (POSS)
  Molecules
• C. Xiao, F. Hagelberg, Poster, presented at the
  11th Conference on Current Trends in
  Computational Chemistry, Jackson, MS, 11/2/03.
• Structures and Dissociation Channels of Metal
  Dications Solvated by Acetonitrile Ligands
• F. Hagelberg, C.Xiao, A. El-Nahas, Poster,
  presented at the 11th Conference on Current
  Trends in Computational Chemistry, Jackson, MS,
  11/2/03.
• Determination of the nonadiabatic content of
  dynamic molecular systems by Electron Nuclear
  Dynamics Theory
• F. Hagelberg, Poster, presented at the 11th
  International Conference on Quantum Chemistry,
  Bonn, Germany, 7/25/03.
• Colloquia
• Silicon clusters with endohedral metal atom
  impurities,
• Department of Chemistry, Johns Hopkins
  University, 1/15/2004
• Molecular cages encapsulating metal cluster
  impurities,
• Department of Physics, Mississippi State
  University, 1/23/2004