SEED: Supporting Emerging Disciplines

SelectionNew directions and disciplines - interdisciplinary, inter-campusSupport more junior faculty, especially MRSEC match positionsHigher riskChosen by Ex Comm

Current1. Nano-Textured Surfaces For Tribological Applicationa; Zou, (UA

Mechanical), and Johnson (OU Physics). Support led to funding for this project NSF CMS-0600642.

2. Characterization of Solid State Nanopore 3D Structure by High Resolution TEM; Li (UA Physics), and Benamara (UA Physics).

3. Fundamental Studies of Model Molecular Plasmonic Devices; Bumm (OU Physics and Halterman (OU Chemistry). Support led to funding for this project NSF DMR-0805233.

4. Ion Transport in Polymer and Organic Liquid Electrolytes; Frech and Wheeler (OU Chemistry).

Fundamental Studies of Model Molecular Plasmonic Devices

Motivation Molecular plasmonics is an emerging field of scientific investigation at the intersection of photonics, chemistry, and nanotechnology.Photonic energy can be manipulated with subwavelength control and interact with adsorbed molecules.

Objective Explore the interaction of adsorbed dyes with nanoparticle plasmon resonances and their plasmon mediated interactions with spatially remote dyes.Explore site specific surface chemistry for controlling dye location on the nanometer scale.

Significance The results will provide guidelines for the rationale design of molecular plasmonic systems.Broad range of potential applications: photonics, sensors, and many other applications.

NSF DMR grant funded (DMR-0805233): Fundamental Studies of Model Molecular Plasmonic Devices, Halterman and Bumm

617 nm

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Discrete-Dipole Approximation (DDA) calculation FGNP on ITO substrate

DARK-FIELDDARK-FIELDMicroscope ObjectiveMicroscope Objective

100x NA 0.9100x NA 0.9

Scattered Scattered LightLight

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Achermann, et al., Achermann, et al., Optics Lett.Optics Lett. 32, 32, 2254 (2007).2254 (2007).

Optical Absorption SpectroscopyMalachite Green Adsorbed on Gold Nanoparticles

before MGbefore MG MGMGwith MGwith MG

zeptomoles of MGzeptomoles of MG(1 zmole (1 zmole ≈≈ 600 molecules) 600 molecules)

by optical absorptionby optical absorptionεε = 1.5×10 = 1.5×1044 nn = 170 zmole = 170 zmole

by adsorption geometryby adsorption geometry

Standing up, edge onStanding up, edge onAA = = ~6.0×10~6.0×10–15–15 nn = 200 zmole = 200 zmole

Lying flat up, edge onLying flat up, edge onAA = ~1.2×10 = ~1.2×10–13–13 nn = 10 zmole = 10 zmole

Measure light scattering before Measure light scattering before and after dye adsorption.and after dye adsorption.

• Measured optical absorption Measured optical absorption is constant with adsorbate is constant with adsorbate coverage estimates.coverage estimates.

• Possible surface enhanced Possible surface enhanced optical absorption. optical absorption.

How many molecules?How many molecules?

Site Specific Surface Chemistry w/ STMCatalytic azide-alkyne “Click” chemistry

Decanethiol Decanethiol HS(CHHS(CH22))99CHCH33

Azide islands Azide islands HS(CHHS(CH22))1010NN33

Molecular sitesMolecular sitesreacted with alkynereacted with alkyne

pp-CH-CH33CC66HH44CCHCCH

50 nm 50 nm × 50 nm STM image× 50 nm STM image100 nm 100 nm × 100 nm STM image× 100 nm STM image

azideazide + + alkynealkyne 1,2,3-triazole link1,2,3-triazole linkcatalystcatalyst

BEFORE REACTIONBEFORE REACTION AFTER REACTIONAFTER REACTION

Research Goal: Use ion beam sculpting parameters to fabricate

thinner and low noise nanopores.

Biomolecule translocation experiments show a relationship between the current drop, ΔIb, and nanopore thickness, H.

DNAb

σVAΔI

H

H

πrσVI

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open Ohmic Conductor: Signal:

Exploring New Methods for Sequencing Single DNA Molecules

Nanopore Sculpting with Different Ion Species

Nanopore Sculpting with different ion species results in different closing rates.Helium exhibits the slowest closing rate, thereby giving the most control over the final pore diameter.

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Electron Energy Loss spectra160 keV4 sec integration, 0.2 eV/channel

Near pore Full membrane50 nm

Initial EELS taken at two positions near the nanopore to help estimate the thickness profile of the nanopore. Data taken in collaboration OU

Nanopore Characterization using Electron Energy Loss Spectra (EELS)

EELS thickness study completed at UA with Benamara

STEM image with STEM image with position numbersposition numbers

Nano-Textured Surfaces for Tribological Applications

Motivation Adhesion and friction are major issues in micro/nano-electromechanical systems (MEMS/NEMS) and miniaturized systems consisting of moving parts.Nanostructures and nano-textured surfaces show novel mechanical and tribological properties.– Size dependent hardness enhancement.– NanoTurf hydrophobic nano-posts produce

40% less drag.Objective

Fundamental understanding of the mechanical and tribological properties of nano-patterned surfaces (NPSs).

Significance The results will provide guidelines for the rationale design of durable, low-adhesion and low-friction NPSs for miniaturized systems.Broad range of potential applications: MEMS/NEMS, computer hard drives, nanoimprinting, and many other applications.

http:/www.seagate.comhttp:/www.seagate.com

Surface with micro-dimples Surface with micro-dimples textured by laser.textured by laser.

Optical micrograph of laser-Optical micrograph of laser-textured zone on the magnetic textured zone on the magnetic

hard drive disk surface.hard drive disk surface.

Ni Nanodot-Patterned Surface Ni Nanodot-Patterned Surface (NDPS)(NDPS)

RF-MEMS adhered RF-MEMS adhered to the substrate.to the substrate.

Nickel Nanodot-Patterned Surfaces (NDPSs)

AFM and SEM allow characterization of the dots and dot array. TEM allows characterization of the crystallinity.

50 nm

Size of NBD beam (70 nm)

Ni {111}

Ni {200}

Si {220}

NiO {111}

100 nm

Ordered array of Ni nanodots: Fabricated by evaporating Ni through an anodized aluminum oxide (AAO) mask.

Apex radiusApex radius 30 nm30 nm

Dot heightDot height 70 nm70 nm

Base diameterBase diameter 75 nm75 nm

Dot-to-dot spacingDot-to-dot spacing 100 nm100 nm

TEM characterization of Ni NDPS shows the polycrystalline nature of the dots

Top-down and oblique-angle SEM images of Ni NDPS.

Mechanical Properties of Ni NDPSs

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Hardness Contact Area Linear Fit (Contact Area)Elastic modulus of Ni nanodots is 160 ± 20 GPa, which is less than bulk nano or micro crystalline Ni (186 and 204 GPa, respectively).

Hardness is 7.7 ± 1.0 GPa, in agreement with that of nanocrystalline Ni (8 GPa), but larger than that of microcrystalline Ni (3 GPa).

AFM (left) and SEM (right) images of a nano-indented array for a 500 μN indentation test.

Hardness & Contact Area vs. Load

Load vs. Displacement Curves

Three load–displacement curves for a 70 μN indentation load.

Tribological Properties of Ni NDPS

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dot removalslight plastic deformation

larger plastic deformation

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Ni NDPS Si(100) Surface

Coefficient of friction for Ni NDPS and smooth Si(100) - 80% reduction at low loads.

Adhesion force for Ni NDPSs and smooth Si(100) - up to 90% reduction.

Friction is proportional to contact area at nanoscale.The critical shear strength of the Ni nanodots/Si substrate interface was estimated to be about 1.24 GPa.In the process of developing a friction model for NDPS.

Correlation between surface topography and the signatures in the lateral force vs. lateral displacement curve for a 0–200 mN scratch

Modeling of Indentation on Ni NDPS

Finite Element Analysis of single asperity contact.

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Experiment (5um tip)Simulation (1um tip)

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Integrate into multi-asperity contact model.

Modeling results are in good agreement with experimental results. The model can thus be used as a design tool for NDPS systems.

Bright-field (BF) TEM image of indented FGNP. Indentation areas enclosed by red

circle with indentation force labeled.

(202) dark-field (DF) TEM image of indented FGNP. Indentation areas enclosed by red circle with indentation force labeled.

500 nm11 μN (300 nm)

5.5 μN (150 nm)

500 nm

5.5 μN (150 nm)

11 μN (300 nm)

Indentation on Flat Gold Nanoparticles

To see damage, from nano-indentation, we must use the TEM to characterize FGNP before & after indention.This requires the FGNPs to be on ultra-thin TEM grids. Here we demonstrate the technique using 50 nm thick Si3N4 grids.

In this preliminary work, individual dislocations within dislocation networks are clearly seen with BF and DF TEM.

Flat gold nanoparticles (FGNPs) are high-quality single-crystal particles with micron lateral dimensions and 20 to 50 nm thick. They are ideally suited to study the generation of dislocation networks etc. under nanoindention.