Otto F. Sankey 1 , Jun Li 1 , Gil Speyer 2 , and John Tomfohr 1 ,* 1 Department of Physics and Astronomy, 2 Department of Electrical Engineering Arizona State University, Tempe, AZ 85287-1504 *Duke University Electron tunneling current through single molecules -- molecular wires and nanoelectronics. Experimental Team: Stuart Lindsay, Nongjian Tao, G. Ramachandran, Anna Moore, Tom A. Moore, Devens Gust, Larry Nagahara (MOT) et al. BYU Sept 09, 2003
Otto F. Sankey 1, Jun Li 1, Gil Speyer 2, and John Tomfohr 1,* 1 Department of Physics and Astronomy, 2 Department of Electrical Engineering Arizona State.
Dec 21, 2015
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Otto F. Sankey1 , Jun Li1, Gil Speyer2, and John Tomfohr1,*1Department of Physics and Astronomy, 2Department of Electrical EngineeringArizona State University, Tempe, AZ 85287-1504 *Duke University
Electron tunneling current through single molecules -- molecular wires and nanoelectronics.
Experimental Team:Stuart Lindsay, Nongjian Tao,G. Ramachandran,Anna Moore, Tom A. Moore, Devens Gust, Larry Nagahara (MOT) et al.
BYU Sept 09, 2003
Outline
• N-Alkanes (CH2 )N
• Carotene
• Light Sensitive
Octane
N-Alkanes (CH2)N+ends
Octane dithiol --- Conducting AFM w/ 1.5nm Au Balls.
Fundamental Curve – Tunneling through one molecule
Au(111) in alkane-thiol“Target” molecule(carotene here)
Au Nanoparticle
Solvent (toluene)
The “Fab”
The Main Physics: Fermi's Golden Rule.
LRRL ,,
)]2/(2/[2||)(||2
eVREeVLERLETL
Elastic Tunneling Theory
|<i| V | f>|2 1st order |<i| T | f>|2 order.T(E)=V+V G(E) V
How: Local Orbital DFT
Self-Consistent with zero bias.
Fireballs, Siesta, VASP(PW)
OctaneDithiol
S-(CH2)8-S
Sandwiched between Au
DEPENDENCE ON
LENGTH
Periodic Molecules
Bandstructure Techniques
(Complex Bandstructure)
Easy way to Find G
For Understanding and making simple esitmates.
E
Fermi-Level Lineup
Bingqian Xu and Nongjian J. Tao. ASU EE. Science 301 1221 (2003) Aug. 29.
Length Dependence of Single Molecule Current. N-alkanedithiols C8, C10, C12 Without Gold Balls.
Peptide Nanotubes
Left-Right-Left-Right-… (8, 10,.. In ring)
(D-Gln)-Phe Glutamine, Phenylalanine
R=(CH2)2-CONH2, R=(CH2)-Phenyl.
Hydrogen Bonded Donuts. (d>4nm)
ABABABABAB……
(Expt. Scripps: Ghadiri, Ashkenasy)
Clicking will bring up netscape. A plugin will play the movie. (Hit BACK to return. Don’t close the window!)
Click here
Carotene
β
Dimerization, (Expt. 1.082) dc cdc c
Tunneling Decay – Effect of Bond Alternation
α=1.299
Theory (- - -)Trans, (….)Cis
Expt. ( ____).
Resistance
Theory Trans (1.2GΩ), Cis(2.2GΩ)
Expt. 5 GΩ
Coulomb Blockade Fit.
Theory (ooo) R2=constant
Theory (ΔΔΔ) R2(V)
Expt. ( ____)
CAROTENE
Photochromic molecules: photoswitching
Open Close
LUMOLUMO
HOMO HOMOEg3.1eV Eg1.7eV
UV
VisRH
RH
S SRR
H
HS S
Conductance: G(close)>>G(open)
• Closed -- way unbroken Open -- way broken
Open Closed
• Eg(Open)2Eg(Closed)•ΨH,L(Open)~on broken ring ΨH,L(Closed)~on polyene backbone
RRH
HS S
RH
RH
S S
Next: States in gap of
OPEN
Next: States in gap
CLOSED
Dynamics: Open Closed
RH
RH
S S
RRH
HS S
1 1’
2 2’
1 1’2’2UV
LUMO
HOMOhν
2 2’1 1’L(π*)
H(π)•
Dynamics: Open Closed
RH
RH
S S
RRH
HS S
1 1’2 2’
1 1’2’2UV
LUMO
HOMOhν
2 2’1 1’L(π*)
H(π)•
AS
SA
Movie Graphic of the HOMO(time) after excitation of light.
Light takes an electron from the HOMO to the LUMO and the molecule starts to jiggle and reconfigure itself to a closed conformation.
Dynamics: Open Closed
RH
RH
S S
RRH
HS S
1 1’2 2’
1 1’2’2
UV
2’
(π*)•
3 3’ 3 3’
3 3’2HOMO(π)
32 3’2’
Localized Delocalized
HOMO
State character.
Dynamics: Closed Open
In progress -- multi-photon
I-V curves (Photochromic Molecule)
S SH
HSH SH S S
H
HSH SH
S S
H
HSH SH
Click here for the movie
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