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mid- IR ( cm -1 ) 500 mJ 10 Hz YAG 1064 nm OPO/OPA MCP ion detector MCP neutral detector reflectron valve pulsed 1 keV electron gun ion beam drift tube YAG PES detector 1064 nm photo- electrons L.M. Posey and M.A. Johnson, J. Chem. Phys., 88, 5383 (1988) Synthesizing and Studying (H 2 O) n and (H 2 O) n ·Ar m
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How Do Networks of Water Accommodate How Do Networks of Water Accommodate an Excess Electron?an Excess Electron?
Nathan I. Hammer, Joseph R. Roscioli, and Mark A. Johnson, Joseph R. Roscioli, and Mark A. JohnsonYale UniversityYale University
International Symposium on Molecular SpectroscopyInternational Symposium on Molecular Spectroscopy 6060thth Meeting – June 20-24, 2005 Meeting – June 20-24, 2005
Kit BowenKit Bowen
Mark JohnsonMark Johnson
Jim CoeJim Coe
Dan NeumarkDan Neumark
Photoelectron Spectra Reveal Three Isomer Classes of (HPhotoelectron Spectra Reveal Three Isomer Classes of (H22O)O)nn
J. V. Coe, et al., J. Chem. Phys., 92, 3980 (1990)J. Kim, et al., Chem. Phys. Lett., 297, 91 (1998)
J. –W. Shin, et al., Chem. Phys. Lett., 399, 349 (2004)J. R. R. Verlat, et al., Science, 309, 93 (2005)
0 10 20 30 40 50 60 70 80 90 1000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
Isomer IIIIsomer III
Isomer IIIsomer II
Ele
ctro
n B
indi
ng E
nerg
y (e
V)
Water Cluster Size n
Isomer IIsomer I
N. I. Hammer, et al., J. Phys. Chem. A, accepted (2005)
Water ClusterWater ClusterFD11 – 11:42
Bulk ?
mid - IR(600-4500 cm-1)500 mJ
10 Hz
YAG
1064 nmOPO/OPA
MCP ion detector
MCP neutral detector
reflectronvalve
pulsed
1 keV electron gun
ion beam
drift tube
YAG
PES detector
1064 nm
photo-electrons
L.M. Posey and M.A. Johnson, J. Chem. Phys., 88, 5383 (1988)
Synthesizing and Studying (HSynthesizing and Studying (H22O)O)nn and (H and (H22O)O)nn
·Ar·Armm
1100 1200 1300
Photon Energy (cm-1)
(D2O)6-
(D2O)4-
(D2O)3-
1500 1600 1700
Photon Energy (cm-1)
(H2O)6-
(H2O)5-
(H2O)4-
Isomer I Binds the Electron Primarily by Isomer I Binds the Electron Primarily by One Water MoleculeOne Water Molecule
N. I. Hammer, et al., Science, 306, 675 (2004)
How Do the Weaker Isomer Classes Bind the Excess Electron?How Do the Weaker Isomer Classes Bind the Excess Electron?
2 3 4 5 6 7 8 9 10 110.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Isomer IIIIsomer II
Ele
ctro
n B
indi
ng E
nerg
y (e
V)
Water Cluster Size n
Isomer I
AA Motif?
OH
0.0 0.2 0.4 0.6 0.8 1.0
(H2O)6
Electron Binding Energy (eV)
I
II
OHOD
HOH
DOD
Photoelectron Spectrum
1100 1200 1300
(D2O)6·Ar2
Photon Energy (cm1)
Electron Binding Energy (eV)
0.0 0.2 0.4 0.6 0.8 1.0
I
II
10 Ar
6 Ar
2 Ar
(D2O)6¯
*
1100 1200 1300
(D2O) 6·Ar 2
(D2O) 6·Ar 3
(D2O) 6·Ar 6
(H2O) 6
(D2O) 6·Ar 8
(D2O) 6·Ar10
1500 1600 1700 1800
1500 1600 1700 1800
Photon Energy (cm1)
(H2O)6·Ar4
Isomer I Only!
1100 1200 1300
1100 1200 1300
Photon Energy (cm1)
AD
AAD
AA
AAD
AD
ADD
Isomer IIIsomer I
ADDAD
AA
AAD ADD
AD
AAD
How Does Isomer II Bind the Excess Electron?How Does Isomer II Bind the Excess Electron?
How High Up in Size Do the Electron Binding Motifs Persist?How High Up in Size Do the Electron Binding Motifs Persist?
0 10 20 30 40 50 60 70 80 90 1000.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
Isomer IIIIsomer III
Isomer IIIsomer II
Ver
tical
Det
achm
ent E
nerg
y (e
V)
Water Cluster Size n
Isomer IIsomer I
Johnson Lab
Prof. Mark A. JohnsonProf. Gary H. Weddle (Fairfield U.)Dr. Joong-Won ShinEric G. DikenJeffrey M. HeadrickJoseph R. RoscioliJoseph C. BoppKevin C. Jones
AcknowledgementsAcknowledgements
Dan NeumarkKit BowenKen JordanJohn Herbert
“Book” Neutral
“Armchair” Anion
“Book” Anion
“Book”AA Anion
How are the Anions Created?How are the Anions Created?
AA
vs.
Collective
• High dipole moment
• Bound to one side of cluster
• Requires much rearrangement from neutral clusters
• Low dipole moment
• Bound to one side of cluster or can be internally solvated in cage of water molecules
• Requires little rearrangement from neutral clusters
Comparing the Two Electron Binding Motifs Comparing the Two Electron Binding Motifs
AA Collective
Examples of the Two Electron Binding MotifsExamples of the Two Electron Binding Motifs