LIGHT AND CURRENT In molecular condution junctions 2014 CaSTL - - PowerPoint PPT Presentation

• A. Nitzan, Tel Aviv University

LIGHT AND CURRENT

In molecular condution junctions Thanks

• W. Belzig, A. Burin, B. Feinberg, M. Galperin, J. Gersten, O. Godsi, P. Hänggi,
• M. Jouravlev, S. Kohler, K. Kaasbjerg, Lehmann, G. Li, M. Oren, T. Seideman,
• M. Sukharev,

2014 CaSTL Summer School, Irvine

MOLECULAR JUNCTIONS

HOT SPOTS

MOLECULAR JUNCTIONS

 

 

 

2 2

( ) / 2

kL kR k k kL kR

E E E         T %

 

1

2

1/2

4 ( ) exp 2 ( )

B

s s

E m U x E dx              



T h

• J. G. Simmons, J. Appl. Phys. 1963 (cited by 2571)

 

B

U x

 

) ( ) ( ( )

L R

f E f e I dE E E 

 

 



T h

fL(E) – fR(E) T(E) eF fL(E) – fR(E) T(E) eF

I

F

Weber et al, Chem. Phys. 2002 g

Landauer formula

 

1

( ) exp ( ) / 1

K K B

f E E k T 



      

h 

INELSTIC ELECTRON TUNNELING SPECTROSCOPY

V

V   h V

h 

h 

incident scattered

Light Scattering

out in-0 in out in-0 in out in-0 in

Localization of Inelastic Tunneling and the Determination

• f Atomic-Scale Structure with Chemical Specificity

B.C.Stipe, M.A.Rezaei and W. Ho, PRL, 82, 1724 (1999)

STM image (a) and single-molecule vibrational spectra (b) of three acetylene isotopes on Cu(100) at 8 K. The vibrational spectra on Ni(100)are shown in (c). The imaged area in (a), 56Å x 56Å, was scanned at 50 mV sample bias and 1nA tunneling current

Recall: van Ruitenbeek et al (Pt/H2)- dips

Dephasing and relaxation are important Relative timescales are important Electron-vibration interactions may be important Transient localization may be important Interaction with light

R.M Hochstrasser and C. A. Nyi,

• J. Chem. Phys. 70, 1112 (1979)

Azulene in Naphthalene matrix (4-35K)

Molecular conduction

molecule

• Fabrication
• Stability
• Characterization
• Funcionality
• Control

MOLECULAR JUNCTIONS

Molecular electronics and plasmonics: The interaction of molecular conduction junctions with light

Junction spectroscopy

(1) Local radiation field associated with the new boundary conditions

(2) Surface “selection rules”

(3) Finite lifetime for electron on molecule (broadening due to electron transfer interaction with metal)

 

 

 

2 2

( ) / 2

kL kR k k kL kR

E E E         T %

(4) Finite lifetime for electronic excitation due to dipolar coupling (energy transfer to e-h pairs in metal)

Junction spectroscopy

(5) With bias – partial

• ccupation may

change absorption and scattering spectra (6) Current may drive light and light may drive current (7) Heat may develop and temperature change may affect spectra

ABSORPTION LINESHAPE

21 6 ,1 ,1 ,2 ,2

2 10 0.1 300 0.01 0.2



            

P NL NR ML MR ML MR

eV eV B B eV T K eV eV  

Fig.2 The absorption current (photons/s). The molecular electronic levels are assumed pinned to the right electrode, i.e. the bias shifts upward the electronic states of the left electrode.

Transfer Rates

{ } l

1

V1r

 

r

 

l

V1l

 

 

2 1 1

2

r

R r R E E

E V  



 

   

 

1 1 1 2 2 1 1 1

( ) / 2

L R L R

E E E         T

= 1 if E=E1 and G

1L=G 1R

 

 

2 1 1

2 ; ,

k

K k K E E

E V K L R  



  

V V V

L

{ } l

R

d

~

d

e  

 1 large d

1 ~ c d d   



 

Ohm’s law!

Dependence on bridge length

N

e 



1 1 1 up diff

k k N

  

     Segal, AN, Davis, Wasielewski, Ratner J. Phys. Chem. B, 104, 3817-3829 (2000)

DNA (Giese et al 2001)

• J. AM. CHEM. SOC. 132, 435(2010)

FRET

(Fluorescence (Forster) Resonance Energy Transfer) R

2 1 2 3

~ k R  

R

6 4

1 1 ~ dS R R



6 3

1 1 ~ dV R R



 

1 1 /

n

efficiency r r   FRET: n=6 SET : n=4

R

6 6

1 ~ Surface Area dS R R



6 6

1 ~ particle volume dV R R



R>>Particle size

2

~

R tot

k 

 

2 3

; ~ Im ~

ent particle

k d r E   



• M. Sukharev, N. Freifeld and AN, J.Phys.Chem C, 2014

   

2 2

1 E n n 3n n

ikr ikr

e ik e k r r r r                    r r r

Electric field from an oscillating dipole in free space

   

2 2 2 4

1 1 1 E ~ 1 r kr kr



         

   

2 2 2 4

4 1 1 E ~ r kr kr         

P

Dynamical equations

= , H E t     r r

= , H E t     r r

= , E H J t      r r r

2 2

( ) =

p r

i         

2

= ; = ; =

p

J aJ bE t a b       r r r

metal

J P t    r r

 

ˆ = ; Tr P n       r r r r molecules

ˆ ˆ ˆ ˆ ˆ = [ , ] d i H i dt      h h

ˆ ˆ = ( ) H H d E t   r r

• M. Sukharev and AN Phys.
• Rev. A 84, 043802 (2011)

LIGHT ON JUNCTIONS

SWITCHES

Light operated molecular switch

NON RESONANCE EFFECTS

Nano Lett. 9, 1615 (2009)

RESONANCE EFFECTS

mg=7 D me=31+/-1.5 D mg=5.5 D me=15.5+/-1.5 D mg=7 D me=30+/-1.5 D CHARGE TRANSFER TRANSITIONS

• S. N. Smirnov & C. L. Braun, REV. SCI. INST. 69, 2875 (1998)

LUMO |2> HOMO |1> L



R



Light induced current in molecular junctions

• resonance mechanism

Current induced light

E21=2eV G

M,1=G M,2=0.1eV

G

N=0.1eV

Observations:

Flaxer et al, Science 262 , 2012 (1993), Qiu et al, Science 299 , 542 (2003),

• G. Hoffmann et al, Phys. Rev. B 65, 212107 (2002)

Yield Intensity

Emission yield from 9-10 dichloroanthracene on a quartz lens coated with ITO (Indium Tin Oxide), a transparent conductor. Flaxer et all, Science, 262, 2012 (1993)

Schematic sketch and energy diagram of a STM junction, in which a single magnesium porphine MgP its molecular structure shown in molecule is adsorbed on a thin insulating alumina film grown on a NiAl110 surface.

Wu, Nazin and Ho, Phys. Rev. B 77, 205430 (2008)

Spatial dependence of the emission spectra from the same molecule as in Fig. 2. The locations of the STM tip where each spectrum was collected are marked in the STMimage of this molecule inset. Inelastic tunneling spectrum of the same electronic transition observed

• n the left by its

emission spectrum. No vibrational resolution can be achieved probably because many vibrations contribute

h 

Photon emission from biased junctions

V

V   h V

Detector sensitivity

The phase structure (chirp) of the pulse determines the temporal

• rdering of its different frequency components that enables us to

control molecular dynamics.

• B. Fainberg and A. NitzanPRB, 76, 245329 (2007)

|1,0> |2,0> |1,w>

Vp

t |1,w(t)>

Total electronic population inversion can be achieved using coherent light-matter interactions like adiabatic rapid passage (ARP), which is based on sweeping the pulse frequency through a resonance.

( ) ( ) t t t      

(

(

w0= e2- e1

h 

h 

Raman Scattering

h 

h 

incident scattered Stokes incident scattered anti-Stokes

( ) ( ) ( ) ( ) ( )

ˆ ˆ ˆ ˆ ˆ ˆ ˆ =

e et b e h e p

H H V V V V V

   

    

v v

† =1,2 † { , † { } † † , }

ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ ˆ = ˆ

k k k k m m R m L i f m

c c d d a b a b H b b

       

    

 

   

   

v v v

 

( ) ( ) ( ) = , † ; †

ˆ ˆ = ˆ ˆ ˆ

et m k et et km mk K L R K m k m k

V V V d c d c





 

† ( ) ( ) =1,2

ˆ = ˆ ˆ ˆ

e e m m m m

Q d V d V

 



v v v

( ) ( )

ˆ = ˆ ˆ

b b

Q U Q V

    



v v v

 

( ) ( ) ( ) 1 2 2 1 † † 2 1 1 2 † † 2 1 1 1 2 2

ˆ ˆ ˆ ˆ ˆ = ˆ ˆ ˆ ˆ

k k k e h e h e h k k k k k k k

c c c V V V d d d c d

   





 

† 2 † ( ) ( ) *( ) { 1 2 ,{ † }} 1

ˆ ˆ = ˆ ˆ ˆ ˆ ˆ

e p e p e p M i f

V a a U U d d d d

        





Molecule Metals Vibration Thermal bath photons

RAMAN SCATTERING

Current

Total Scattering Stokes and antistokes intensities

RAMAN SCATTERING

= ln /

v S aS i i v i i v

T J J       



   

Temperature from S-As ratio Comparing temperature by two methods

frequency renormalization, damping and heating of vibrational modes in nanoscale junctions

“Figure 3b shows another feature that is observed with some regularity in such junctions: a systematic shift in energy of 15 cm21 is observed for most (Stokes) vibrational modes as a function of V. This is an example of a Raman Stark shift.” Ward, Corley, Tour, Natelson (Nature Nanotechnology 1/11)

OPV3

d–f, The same data for the OPV3 device used for Figs 1 and 3. The data in d,e,f demonstrate that bias- driven electronic heating is also detectable in junctions that show optical pumping and bias-driven vibrational heating.

Electronic heating under bias. a, Effective temperature (blue; left axis) and dissipated electrical power (red; right axis) versus bias voltage V in a nominally bare device. Error bars are described in the text. Inset: current/voltage curves for this

• device. Error bars are described in

the text. b,c, Raman response shown as a Raman signal (in CCD counts) as a function of voltage and Raman shift (b), and as the Raman intensity (in CCD counts) as a function of Raman shift (c) at three different voltages (blue lines); the green lines are best fits to the data given by equation (2). Only the anti- Stokes signals are shown in b and c. This device shows no molecular Raman peaks, and is considered a ‘clean’ junction. Ward et al, J. Phys. Chem. Lett. 2011, 2, 2110–2113

Raman scattering from biased molecular conduction junctions: The electronic background and its temperature

• M. Galperin and AN , PRB 84, 195325 (2011)

         

1 2T

SS K K K K

f E f E E f E f E       

 



 

 

, 2 T

SS eff K K K

dE E E f E f E T         



• M. Galperin, AN J. Phys. Chem. Lett. 2011, 2, 2110–2113

Electron-vibration interactions

Linear el-vib interaction: Quadratic el-vib interaction: Frequency shifts due to charging

x Kristen Kaasbjerg, Tomas Novotny and AN, PRB 88, 201405(R) (2013)

OPV3 junction

El-vib couplings:

vibrations and couplings calculated

with DFT for the neutral molecule (adiabatic approx.)

field effects neglected no nuclear relaxation

OPV3 spectral function

Off-resonant single-level junction

Parameters

Lu, Hedegard, Brandbyge, PRL 2011

Summary

• Light in junctions
• Optical conduction switching
• Light induced current
• Current induced light
• Raman Scattering
• Vibrational spectroscopy in

conduction junctions

• Exciton-plasmon interactions
• Energy transfer rates –

molecule to nanoparticle