Different strategies for single molecule detection through nanoplasmonics

Transcription

1 Different strategies for single molecule detection through nanoplasmonics Enzo Di Fabrizio - Remo Proietti Zaccaria Istituto Italiano di Tecnologia (IIT) IIT Genova Magna Graecia University

2 What is NanoPhotonics/Plasmonics? a) b) 20 m 100nm Nanophotonics is the interaction of light with micro/nanometric structures in order to realize optically induced phenomena such as: light harvesting waveguiding (photonic crystals, quasi crystals, fibers, etc.) wavefront engineering near-field microscopy (STM, SNOM) near-field spectroscopy (SERS, TERS, SPPERS) plasmonics (metallic-like nanodevices) 1

3 COMPLEX SYSTEM Why NanoPhotonics? COMPLEX SYSTEM Photonics Device oriented nanophotonics COMPLEX SYSTEM COMPLEX SYSTEM 2

4 Light is fun 3

5 Light is science Micro machine Cloaking device Photonic Crystal (PhC) X-rays zone-plate 4

6 Outline Planar structures & Photonic crystals Metallic structures & Plasmonics AFM-Raman: toward few/single molecule detection Adiabatic compression in details (not too many though) Detection in Attomolar solution concentration Artificial Lotus effect Computational approach: a very powerful resource Few photons problem Electroporation Modulated SPPERS Adiabatic electrical generation Hot electrons nanoscopy THz antennas Optical computing Opto-mechanics Plasmo-catalysis Thermo-catalysis 5

7 What is nanofabrication? 6 Bottom-up & Top-Down approaches

8 Planar nanostructures 3D PH. Crys. By X-ray lithography 2D Bragg reflector Si/SiO2 Coll. F. Priolo Topographic lenses a-si 2D Photonic Crystal Coll. F. Pirri group 7

9 A little something about Photonic Crystals 1D 1D PhC n1 n2 n1 n2 n1 Light? 2D 3D 2D PhC Fundamental request: translational periodicity 8

10 Photonic crystals: the cradle of photonics 9 Ingredients: Different materials (no bulk) Dielectric or metal (absorption) Translational symmetry (1D, 2D, 3D) What we can do: Filters Hot spot cavities with high Q factor Planar waveguides Fibers Fano modes Extention to quasi-crystals (self-similarity) Explain natural phenomena (butterfly color) Color changing paints Nonlinearity: optical computing

11 Metallic standing nanostructures Elongated dimer nanostars (flowerlike) patterns were fabricated with Electron Beam Lithography. H = nm IPS = 6-250nm Branch 70 nm core 80 nm SERS applications Elongated Nanostar (flower-like) dimer pattern 10

12 A little something about Plasmonics The problem of optics (but not only): diffraction limit ( /2) How can we see things at the nanoscale with visible/ir/thz light (>400nm)? Surface Plasmon Polaritons (SPP)= surface electromagnetic wave Light is compressed without changing the carried energy High spatial resolution (nm scale) z light line =kc/n bulk SPP bulk dielectric metal x SPP line: light is compressed! k x ~1/ Conservation law: k x 11

13 Outline Planar structures & Photonic crystals Metallic structures & Plasmonics AFM-Raman: toward few/single molecule detection Adiabatic compression in details (not too many though) Detection in Attomolar solution concentration Artificial Lotus effect Computational approach: a very powerful resource Few photons problem Electroporation Modulated SPPERS Adiabatic electrical generation Hot electrons nanoscopy THz antennas Optical computing Opto-mechanics Plasmo-catalysis Thermo-catalysis

14 Combination of AFM-Raman spectroscopy 12 Raman & force measurements Open challenge: nanodevice on a cantilever efficiently acting as AFM tip and as a nanontenna for Raman scattering. F Force measurements d

15 Intensity Tapered plasmonic waveguide 13 Mark Stockman, PRL 93, (2004) Electric field Effective refractive index Phase velocity

16 5fsec radial excitation (band width: 0.1PHz-0.85PHz, 350nm-3 m) Adiabatic compression Nmerical simulation Calculation Scalar E field Vector E field De Angelis et al., Nature Nanotech. 5, 67 (2010) Radial mode (TM0) benzenethiol Tip radius < 10nm High spatial resolution Adiabatic compression Energy at the nanoscale 14

17 15 Fabrication process: pillar growth Electron Beam 5 Kev, 2 nm spot Pt precursor gas gold Si-N Membrane 15 nm 100 nm pillar height 2.5 m pillar base 100 nm Tip radius of curvature nm

18 Single QD Raman spectrum 16 Amine peak estimated 10 NH 2 groups (from company linkage data) maximum 80 NH 2 groups De Angelis et al. Nano Lett., 8 (8), (2008)

19 QDs manipulation and deposition on the NW 17

20 Adiabatic cone on PhC 18 Di Fabrizio, E., et al., Italian patent n. TO2008A nm radius Gold and Silver cones

21 AFM-Raman spectroscopy 19 Nanodevice on a cantilever efficiently acting as AFM tip and as a nanontenna for Raman scattering.

22 Optical setup Focal plane on the cantilever Focal plane on the tip end TASC CBM Trieste 20

23 Raman & AFM: chemical sensing 21 Laser lithography Si/SiO2 (optical image) Silicon nanocrystal Cantilever with Nano-Cone 10 m silica SiO x Raman Band Si Raman Band

24 Raman & AFM: chemical sensing, coarse scan 22 Silicon nanocrystal Cantilever with Nano-Cone silica p1 p2 p3 p4 p5 p6 p7 p8 p9 p10 2 m Scan length 2 µm Scan step ~220 nm

25 Raman & AFM: chemical sensing, fine scan Simultaneously: Topography Raman intensity at 520 cm -1 AFM topography Sensing and topography resolution 5-10 nm From Raman detailed line shape analysis we found nano crystal size 5-7 nm 110 nm Fine scan along the wall. AFM scan step: 7 nm 23

26 Selected results 24

27 Nanocone on biological samples Lipid bilayers in liquid: 4 nm thickness. Sharp topography without shear effects. Nanocone performs exceptionally well on biological samples in physiological environment Force spectroscopy on titin protein Topography on insulin fibrils in liquid: down to resolution of protofibrillar structures (3-4 nm). Only 1 report in literature. Titin Pulling 25

28 Recent results:sers on amyloid fibrils (on silicon) Amyloid fibrils are involved in Alzheimer disease. Their characterization by AFM is widely used, however to date there are few reports about their Raman signature. Here we show that insulin fibrils on silicon, bear a Raman signature (1), compared to the background (2). 1 um scan (topography)

29 Adiabatic compression: behind the scenes 27 Strong field SPP Ag laser (visible)

30 Adiabatic compression: behind the scenes 27 Strong field SPP Ag What kind of source? laser (visible)

31 28 The source z x Plane wave X-polarized Radial polarization y z x

32 3D simulation: radial-like source 29 z x 500nm Adiabatic compression Field enhancement ~100 Strong localization

33 3D simulation: longitudinal plane wave X 30 z x 500nm NO Adiabatic compression Phase dependence Field enhancement ~20

34 Summarizing Nmerical simulation Calculation Nature Nanotech. 5, 67 (2010) Radial mode (TM0) benzenethiol Tip radius < 10nm High spatial resolution Adiabatic compression Energy at the nanoscale Opt. Exp. 19, (2011) PRB 86, (2012) Opt. Lett. 37, 545 (2012) 31

35 Outline Planar structures & Photonic crystals Metallic structures & Plasmonics AFM-Raman: toward few/single molecule detection Adiabatic compression in details (not too many though) Detection in Attomolar solution concentration Artificial Lotus effect Computational approach: a very powerful resource Few photons problem Electroporation Modulated SPPERS Adiabatic electrical generation Hot electrons nanoscopy THz antennas Optical computing Opto-mechanics Plasmo-catalysis Thermo-catalysis 32

36 Diffusion limit 33 1 fm analyte concentration

37 Question: can the diffusion limit be avoided? SuperHydrophobicity for analyte concentration 34 Evaporation implies concentration and localization

38 Artificial Lotus effect: micropatterned surface 35 Photolithography combined with Deep RIE Full controllable size High aspect ratio (up to 20 or more) Both rigid and flexible substrates 10 m

39 Artificial Lotus effect 36 Evaporation of 10 ml of water in few minutes

40 36 Artificial Lotus effect Evaporation of 10 ml of water in few minutes Few molecules... and we know where they are!

41 Evaporation and concentration (10 Attomolar) Rhodamine 37

42 Intensity (arb. units) 38 Raman detection of Rhodamine on pillars 10 l mol/l Rhodamine 6G Raman shift (cm -1 ) Roughly 10 Rhodamine molecules!

43 Combination of Plasmonics and hydrophobic surfaces m 4 m 200 nm

44 Combination of Plasmonics and hydrophobic surfaces 40 3 m 50 nm

45 Combination of Plasmonics and hydrophobic surfaces 41 m m m m

46 Selected results 42

47 Outline Planar structures & Photonic crystals Metallic structures & Plasmonics AFM-Raman: toward few/single molecule detection Adiabatic compression in details (not too many though) Detection in Attomolar solution concentration Artificial Lotus effect Computational approach: a very powerful resource Few photons problem Electroporation Modulated SPPERS Adiabatic electrical generation Hot electrons nanoscopy THz antennas Optical computing Opto-mechanics Plasmo-catalysis Thermo-catalysis 43

48 #1: Few photons sub-wavelenght transmission =514/530nm d: 30nm-200nm Noise Signal 200nm very high signal to noise ratio ~ 100 field localization European project: FOCUS z=150nm along x (nm) (I hole /I bg ) x ~1400 and (I hole /I bg ) y ~120 Very high signal to-noise ratio! ~E nm nm Z Max E ~1.7V/m Decay of E along z (nm) (side hole) (I hole /I bg ) x ~1400 and (I hole /I bg ) y ~120 Very high signal to-noise ratio! ~E 0 hole Polarization: X Holes diameter: 80nm nm nm ~10nm 1/e 0: 530nm Period: 1 m 44

49 #1: Few photons sub-wavelenght transmission =514/530nm d: 30nm-200nm Noise E field travelling through the slab Signal 200nm very high signal to noise ratio ~ 100 field localization z=150nm along x (nm) (I hole /I bg ) x ~1400 and (I hole /I bg ) y ~120 Very high signal to-noise ratio! ~E nm nm Z Max E ~1.7V/m Decay of E along z (nm) (side hole) (I hole /I bg ) x ~1400 and (I hole /I bg ) y ~120 Very high signal to-noise ratio! ~E 0 hole Polarization: X Holes diameter: 80nm nm nm ~10nm 1/e 0: 530nm Period: 1 m 45

50 #2: Computational electroporation 46 = electrode Va Vb Vc

51 #2: Computational electroporation 47 DNA is negatively charged

52 Unfolded protein #3: Modulated SPPERS (Energy/Life) Propagating light Folded protein Adiabatic compression! Localized light Logic ports (1/0 unit) optical computing Near/Far-field Spectroscopy Au 1 m 48

53 #4: Electrically generated energy concentrator Laser approach Electrical approach a) b) Narrow excitation range Hot electrons injection Wide excitation range ~V Not yet possible (maximum frequency: 100 GHz; Visible: 500THz) Electrical contribution: adiabatic compression Magnetic contribution: spectroscopical shift Near-field magnetic probe? Magnetic compression?

54 m AFM #5: Plasmonic hot electrons nanoscopy GaAs: Egap=1.42eV 5 m Hot electrons map and morphology map 500nm =1060nm (1.17eV); P=2.43 m; d=365nm; Tip radius= 25nm Highly efficient photon-tohot electrons conversion (>30%)! (k vector from the cone) 50

55 Diffraction limit: /2 Solution: resonant plasmonic nanoantennas 51 #6: THz antennas (0.1-10THz) Characteristics of THz: can penetrate inside most dielectric materials that may be opaque to visible light has low photon energies that do not cause photoionization in biological tissues Applications of THz: imaging of plastic/ceramic/semiconductors (e.g, quality control) spectroscopy (semiconductors, molecules, DNA, proteins)

56 #7: Optical computing 52 Logic gate: AND T-shape antenna: Fano mode

57 #8: Opto-mechanic interactions at the nanoscale V Rb = 60nm H = 3.5 um T_polymer = 30nm (SU8) Rho = Kg/m 3 (SU8) Young_mod = *10 8 (1/10 SU8) Poisson_ratio = 0.33 Core = 30nm Au Immagine SEM V V da Mario Applications: time (msec) resolved spectroscopy (quality factor, force spectroscopy, sensing) microfluidics optofluidics V V m 53

58 #9: Plasmocatalysis UV e- TiO 2 h + OH - O - 2 O 2 *OH Two main issues: 1) UV light (<5% total) Visible with doping (nitrogen, tungsten, etc.) 2) High e-h recombination rate & low light absorption Resonant plasmonic nanodevices Bayarri et al., Chem. Eng. J. 200, 158 (2012) c) Al J. Mater. Chem., 2008, 18, superhydrophobicity! Nature Nanotech. 247, 8,

59 e.m. field heat source temperature Temperature (K) 55 #10: Localized high temperature catalysis Single gold nanoantenna =1070nm; P=15 W; Waist=1 m; L=500nm; W=25nm 440 Rb K 300 Joule effect: P =J E Conduction heat transfer: P= T S k/d, k air =0.026 Below 1000 C: Ag=961 C - Au=1065 C - Al=595 C Ti=1670 C - Cu=1083 C - Cr=1857 C Pt= 1768 C

60 Thank you!

61 Extra Remo Proietti Zaccaria Istituto Italiano di Tecnologia (IIT)

62 Computational/analytical research flow chart Photonic Crystals Plasmonic structures Fundamentals: symmetry mode in slab cavities Application: SPPERS* Applications: Super-lenses Sub-wavelength sensors Fundamentals: Quasicrystals properties Quasicrystals Application: Quasicrystals fibers Fundamentals: Adiabatic devices Super-long SPP Metallic Photonic Crystals Fundamentals: High Q factor & Low modal volume *Surface Plasmon Polaritons Enhanced Raman Spectroscopy; SMD project Focus project Nanoantenna project E1

63 Computational and analytical instruments E2 RSoft Lumerical CST Comsol Finite Difference Ttime Domain (FDTD) Finite Integrate Technique (FIT) Robust but not versatile Finite Element Method (FEM) Less robust than CST but very versatile Plane wave expansion (PMW) Rigorous Coupled Wave Analysis (RCWA) Finite Difference Time Domain (FDTD) Mathematica Analytical tool

64 Plasmonic at the DUV range (Life/Energy) Extinction eff. Extinction Experiment Simulation Al/Al 2 O 3 nanoparticles array 5.8eV! E near-field Energy (ev) ACS Nano 2013 E3

65 E4 High temperature catalysis (Env.) Matrix of gold nanoantennas 400nm Localized temperature pattern!

66 KAUST 2013 E5 V V V V V=1 V=0.3V V V V V V V