1. Non-linear photochromism in the near-field of a nanoplasmonic array
Christopher Otolski
University of Kansas

2. Control on the smaller scale

3. Enhanced Electric Field
Christos Argyropoulos (UNL)

4. Diarylethene Photoswitch (DAE)}
Two-photon Excitation at 800nm

5. Experimental Design Absorbance 𝐴𝑏𝑠=− log 𝑇 𝑖 𝑇 𝑓 400 500 600
Wavelength (nm)
Wavelength (nm)
𝐴𝑏𝑠=− log 𝑇 𝑖 𝑇 𝑓
Frame rate = 25 fps

6. Plasmonic Substrate Plasmonic Array Scanning Electron
Microscopy
Atomic Force Microscopy
Gold Nanorods 50 nm nm
Herman Batelaan (UNL)
Federico Capasso (Harvard)
*Gold nanorod has plasmon resonance at 800nm

7. DAE on the plasmonic array
Total time 30 min

8. Glass vs plasmonic array substrate
Enhanced field profile

9. DAE on the Plasmonic array

10. Modeling DAE conversion
I 0 = initial intensity
∆N=change in molecuels
N=number density
Δz=film thickness
σ 1PA =one photon cross section
𝜎 1𝑃𝐴 =1𝑥 10 −22 𝑐𝑚 2 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒
σ 2PA = two photon cross section
𝜎 2𝑃𝐴 =5.5𝑥 10 −50 𝑐𝑚 4 ∙𝑠 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒∙𝑝ℎ𝑜𝑡𝑜𝑛

11. Modeling DAE conversion
Grid: contains number of molecules
∆N=𝑁 𝐼 0 Δ𝑧( 𝜎 1𝑃𝐴 + 𝜎 2𝑃𝐴 ℎ𝜐 𝐼 0
Enhanced field profile
Grid size 110x195

12. Modeling DAE conversion
Grid: contains number of molecules
Number of molecules
Grid size 110x195

13. DAE on Plasmonic array

14. Anisotropy of the DAE thin film
Enhanced field
Profile for 580nm probe
Enhanced field
Profile for 800nm pump
𝐸 𝐸 0 nm nm

15. DAE on Plasmonic array

16. Anisotropy of the DAE thin film
Enhanced field
Profile for 800nm pump
Enhanced field
Profile for 580nm probe
𝐸 𝐸 0 nm nm

17. DAE on plasmonic array

18. Nanoplasmonic interactions
Electron Transfer Au
Enhanced field
Thermal

19. Conclusion
Two-photon excitation of photoswitch in enhanced near-field.
Modeling the absorbance decay shows excellent agreement with experiment.
Spatial and polarization dependencies play an important roll in the enhanced near-field.

20. Acknowledgments Funding: Special Thanks: Herman Batelaan
Christos Argyropoulos
Sasanka Ulapane
Funding:
This material is based upon work supported by the National Science Foundation under Award No.
IIA‐ and IIA‐  

22. Absorption spectrum of DAE thin film
𝝈 𝟏𝑷𝑨 =𝟔 𝒙 𝟏𝟎 −𝟏𝟕 𝒄𝒎 𝟐 𝒎𝒐𝒍𝒆𝒄𝒖𝒍𝒆
𝝈 𝟏𝑷𝑨 =𝟏 𝒙 𝟏𝟎 −𝟐𝟐 𝒄𝒎 𝟐 𝒎𝒐𝒍𝒆𝒄𝒖𝒍𝒆

23. DAE switching on Glass
Conversion shown with 400nm laser irradiation

24. DAE on glass substrate
White light probe only

25. 1PE vs 2PE with DAE thin film
* 800nm exposure occurred for 15 minutes in both experiment and simulation

26. Conclusion 𝐸 𝐸 0 2 55 Thermal Heating Plasmonic Field-Enhancement
Hot electron
transfer
𝐸 𝐸 55
Guillaume, B.; Quidant, R., Nanoplasmonics for chemistry. Chem. Soc. Rev. 2014, 43,
Dombi, P.; Hörl, A.; Rácz, P.; Márton, I.; Trügler, A.; Krenn, J. R.; Hohenester, U., Ultrafast Strong-Field Photoemission from Plasmonic Nanoparticles. Nano Letters 2013, 13 (2),

27. Transmission measurement on plasmonic array

28. 1PE vs 2PE with DAE thin film
∆𝐼=𝑁 𝐼 0 Δ𝑧( 𝜎 1𝑃𝐴 + 𝜎 2𝑃𝐴 ℎ𝜐 𝐼 0
* 800nm exposure occurred for 15 minutes in both experiment and simulation

29. Plasmonics Baffou, G., Quidant, R. Chem. Soc. Rev., 2014, 43, 3898
Guidez, E., Aikens, C. Nanoscale, 2014, 6, 11512
Baffou, G., Quidant, R. Chem. Soc. Rev., 2014, 43, 3898

30. Scanning Electron Microscopy
Plasmonic Substrates
Plasmonic Array
Atomic Force Microscopy
Scanning Electron Microscopy
15µm
Gold Nanorods 50
0µm
0µm
15µm
Missing nanorods
Becker, et al., Ann. Phys., 2013, 525, L6–L11

31. Current works with Plasmons
Surface Enhanced Raman Spectroscopy (SERS)
1. Sharma, B.; Frontiera, R. R.; Henry, A.-I.; Ringe, E.; Van Duyne, R. P., SERS: Materials, applications, and the future. Materials Today 2012, 15 (1–2),

32. Current works with plasmons
Thermal
Heating
Plasmonic
Field-Enhancement
Hot electron
transfer
𝐸 𝐸 55
Guillaume, B.; Quidant, R., Nanoplasmonics for chemistry. Chem. Soc. Rev. 2014, 43,
Dombi, P.; Hörl, A.; Rácz, P.; Márton, I.; Trügler, A.; Krenn, J. R.; Hohenester, U., Ultrafast Strong-Field Photoemission from Plasmonic Nanoparticles. Nano Letters 2013, 13 (2),

33. Plasmonic field enhancement
Enhanced field
profile
𝐸 𝐸 0
Thermal
Heating
Plasmonic
Field-Enhancement
Plasmonic
Field-Enhancement
Hot electron
transfer
Christos Argyropoulos (UNL)