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Tatsuya Higaki, Meng Zhou, Kelly J. Lambright,† Kristin Kirschbaum,† Matthew Y. Sfeir,‡ and Rongchao Jin
Sharp Transition from Nonmetallic Au246 to Metallic Au279
with Nascent Surface Plasmon Resonance
Department of Chemistry, Carnegie Mellon University
Introduction
Transition Regime
0.1 nm 1 nm 10 nm 100 nm
Plasmonic Nanoparticles
Molecular Excitation (Eg > 0)
Atomically-Precise Nanoclusters
MetallicNonmetallic
Au~520Au333Au144Au133……
2.9 nm2.3 nm1.7 nm1.6 nm
……
?
Plasmonic Excitation (Eg = 0)
Au
S
How the
Transition
Occurs?
Au133(S-Ph-tBu)52 Au144(S-CH2Ph)60
Crystal Structures by SC-XRD Model Structures by TEM
Atomically-Resolved Surface Pattern
Objectives & Methods
Unveil Critical Sizes and the Structures for the Transition!
I. Atomically-Precise Synthesis of Aun with 200 < n < 300
II. Structure Determination of Aun by X-ray Crystallography
III. Quantum State Determination of Aun by Spectroscopy
(Collective Mode)
Atomically-Precise Syntheses
Crystal Structures
“Size Focusing”
[(C8H17)4N][AuBrxCl4-x] in Toluene
Stirred at 80˚C
w/ excess thiols
NaBH4
Aux(SR)y
Au246(SR1)80 Au279(SR2)84or
or
MALDI-MS+
1 2
Result I&II: Syntheses & Structures
Decahedral Core
in Au246
Au279(SR)8
4
Inte
nsity (
a.u
.)
m/z
Au246
Cuboctahedral Core
in Au279
Au
S
e.g.,
1.8
1.6
1.4
1.2
1.0
0.8
e-p
h C
ou
plin
g T
ime (
ps)
3002001000
Pump Power (nJ/pulse)
5.0
4.8
4.6
4.4
4.2
4.0
Decay T
ime C
onsta
nt (p
s)
3. Higaki, T. et al. J. Am. Chem. Soc. 2018, 140, 5691.
7. Zhou, M.; Zeng, C.; Song, Y.; Padelford, J. W.; Wang, G.; Sfeir, M. Y.;
Higaki, T.; Jin, R. Angew. Chem., Int. Ed. 2017, 56, 16257.
4. Zeng, C. et al. Science 2016, 354, 1580.
Merely 33 Au-Atoms Difference Induced the Transition!
h
e
Conclusion
Q: Critical Sizes from Nonmetal to Metal Transition?
A: Au246(SR)80 and Au279(SR)84!
h
e
h
e
MetallicNonmetallic
EgEF
Nanoparticles
Diameter (nm)
Au246Atoms Au279
0.1 nm 1 nm 10 nm 100 nm
Reference & Acknowledgement†Department of Chemistry and Biochemistry,
University of Toledo‡Center for Functional Nanomaterials,
Brookhaven National Laboratory
Collaborators:
Result III: Optical Properties
Femtosecond Spectroscopy
Femtosecond
Laser Pulse
2. Probe
1. Pump
Au246 or Au279
in Toluene
Laser Power vs Time
900700500300
Wavelength (nm)
Ab
s. (a
.u.)
UV-Vis Spectra
600
506
400
Au279(SR)84
Au246(SR)80
460
Single Peak
Multiple
Peaks
E (eV)
Molecular Excitation
a b c
e.g., Au25(SR)18
Plasmonic Excitation
Multiple Peaks → Nonmetal
e.g., Large Au NP
400 500 600 700 800 900
Wavelength (nm)
Ab
s. (a
.u.)
Metal → Single Peak
Slope > 0
→ Metallic
Slope ~ 0
→ Non-Metallic
Au279(SR)84
Au246(SR)80
1. Jin, R. et al. Chem. Rev. 2016, 116, 10346.
2. Hartland, G. V. Chem. Rev. 2011, 111, 3858.
5. Sakthivel, N. A. et al. J. Am. Chem. Soc. 2017, 139, 15450.
80 nm50 nm30 nm20 nm10 nm3 nm
100 nm
Diameter
Au279(SR)84Au246(SR)80
3. Analyze
Relaxation Time
fcc model
Atomically-Defined
Size & Structure!
AuI
S S
“Staple”
motif
6. Higaki, T. et al. Proc. Natl. Acad. Sci. U.S.A. 2019, 116, 13215.