Recent Advancements in Nanoscale IR Spectroscopy and Imaging

Anirban Roy, Qichi Hu, Honghua Yang, Miriam Unger and Curtis Marcott

Outline

• Company Background

• Introduction to AFM-IR

• Latest AFM-IR Advancements

• Resonance Enhanced AFM-IR

• HyperSpectral Imaging/Spectroscopy

• Tapping AFM-IR Imaging/Spectroscopy

• Technical Overview

• Applications

• s-SNOM Technology and Applications

• Tunable IR Laser Options

• Summary

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Bruker Nano Acquires Anasys Instruments

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• Bruker Nano Surfaces Division acquired Anasys Instruments Corp on April 10th 2018

• All nanoIR products are now integrated into the Bruker Nano Product Support

Nanoscale IR spectroscopy

nanoIR™ 1st Generation

AFM-IR

nanoIR2™ 2nd Generation AFM-IR

Top Down Configuration & Resonance Enhanced

nanoIR2-s™ Combined

IR s-SNOM & AFM-IR

nanoIR2-FS™ 3RD GenerationFASTspectra

2010 2014 2015

2016 2017

Tapping AFM-IRHYPERspectra

NEWnanoIR3™

Latest Generation nanoIR platform with

Tapping AFM-IR

2018

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Infrared Spectroscopy Introduction

2 ≠ 0 01 = 0 0

IR Spectrum

Source: Wikipedia

IR light wave

Power and Limitations of Infrared Microspectroscopy

Multilayer film, courtesy of Dr. Curtis Marcott

0

.5

1

1.5

2

1800 1600 1400 1200 1000

Wavenumber

Ab

so

rb

an

ce

PET

Tie Layer

EVOH

LDPE

FT-IR

IR microspectroscopy

annual publications

microscope

IR spectra Chemical Image IR microspectroscopy

applications

• Materials Science

• Consumer products

• Pharmaceuticals

• Life sciences

• Health & beauty

• Forensics

Abbe diffration limit:

Practical resolution many microns

AFM-Based IR Spectroscopy (AFM-IR)

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Time (ms)

Dazzi, A.; Prazeres, R.; Glotin, F.; Ortega, J.M.; Opt. Lett. 2005, 30, 2388-2390.

Ernst AbbeAlexandre Dazzi

2014 Ernst Abbe Award

Nanoscale IR Spectroscopy

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nanoscale infrared imaging & spectroscopy capabilities

Chemical composition & nanoscale property mapping

Nanoscale IR chemical analysis

Rich, interpretable spectra

directly correlates to FTIR

Monolayer sensitivity & high spatial resolution

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Organic nanoContaminants

Polymer blends & Block

Copolymers

Multilayer films Nanofibers

Nano-Composites

Broad range of nanoIR applications

+++

Perovskites &

Solar CellsnanoIR spectra

2D Materials/Graphene

Life Science

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Resonance Enhanced Mode

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Deflection signal

laser signal

Resonance Enhanced Mode

Laser repetition rate

Forced resonance makes AFM-IR more sensitive

Single Monolayer Sensitivity

F. Lu, M. Jin, and M.A. Belkin, Nat. Photonics 8, 307–312 (2013).

Resonance enhanced AFM-IR of PEG monolayer

Topography IR image at 1340 cm-1

C-O-C AsymCH2 wag

CH2 scissor

Halobacterium

Salinarum deposited

on a Au substrate

Amide

IAmide II

To

po

gra

ph

y

IR Im

ag

e

at 1

54

0 c

m-1

3 x 4 μm

Purple Membrane (Resonance Enhanced AFM-IR)

QCLs are getting faster!

0

0.2

0.4

0.6

0.8

1

1.2

7809801180138015801780

Ab

sorp

tio

n (

au)

Wavenumber (cm-1)

Single spectrum, 400 msec sweep, 0.2 msec time constant, no averaging

Anasys AFM-IR 100 msec

FTIR

Faster Scanning Enables Hyperspectral Imaging

X

Y

A

B

C

Figure 5. Illustration of the hyperspectral image cube. High speed AFM-based IR spectroscopy allow for the first time practical hyperspectral imaging, i.e., where spectra are mapped at matrix of XY points. One can extract segments of the hyperspectral cube to obtain (A) chemical maps that show spatial variation in absorption at a given wavelength, (B) spectral line maps showing the variation in spectra in one direction, or (C) individual spectra at any X,Y location.

Hyperspectral image cube

Hyperspectral animation

5-mm x 5-mm, 50 x 50 spectrum array on PS/PMMA/epoxy blend

Move cursor onto above image and click on arrow to start animation

Hyperspectral array PCA weight maps

AFM image PS PMMA Epoxy

5-mm x 5-mm, 50 x 50 spectrum array on PS/PMMA/epoxy blend

• New hyperspectral imaging provides point by point spectra over a large

number of data points to provide an array of spectra and chemical images

at specific wavenumbers

• Principle component analysis can be applied to identify specific chemical

components and their spatial distribution

nanoIR3-s™ S-SNOM - High Performance s-SNOM Imaging

• IR s-SNOM platform for optical & chemical Imaging• Supports multiple laser types, visible, nearIR• Electrical nanoscale property mapping• Upgradeable to nanoIR-spectroscopy

NEW nanoIR3 platform configurations

nanoIR3-s™ High Performance IR nano-spectroscopy

• Complementary s-SNOM & Tapping AFM-IR• Highest Performance IR nano-spectroscopy• Broadband Spectroscopy & Chemical Imaging• Nanoscale property mapping• Versatility & Easy to Use

nanoIR3™ - Latest Generation nanoIR platform with Tapping AFM-IR

• Highest performance nanoIR spectra with AFM-IR• Sub-10nm resolution IR chemical imaging with Tapping AFM-

IR• Correlates to FTIR & industry databases• Easy to use for fast, productive measurements

s-SNOM imaging Phase and Amplitude on HbN

Plasmonic Imaging on Graphene with Tapping AFM-IR & s-SNOM

nanoIR Spectroscopy of Polyethersulphone (PES)

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Sample Environmental Control

Sample transfer port for nanoIR3-s

• Protects sample in controlled gas environment from glove box to nanoIR system to protect

• includes integrated humidity sensor with optional high sensitivity humidity and oxygen sensors

Humidity control & heater & cooler

• For control of humidity/gas & temperature for in-situ AFM-IR

• 4% to 95% non condensing

• 4°C to 80°C heating and cooling

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IR Polarization Control & extended IR range

Polarizer OptionOptional & upgradeable

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nanoIR nanoscale property mapping modes

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Tapping AFM-IR: Technical OverviewConcept

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Zt : Distance of the Tip

Zs : Sample expansion (photothermal)

k/g : Linear/non-linear force constant

as: Absorption coefficient

at: Tip oscillation amplitude

wp: Laser pulse rate

wn: cantilever eigen mode frequency (n=1,2,3…)

Resonance Condition: w1 + wp = w2

Fundamental

mode Pulse

rate

2nd Eigen

mode

zt

zs

n

n

n n

Tapping AFM-IR: Technical OverviewSchematic

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Heterodyne Force Microscopy

M.T. Cuberes, J. Nanomater., 2009

Resonance Condition:

w1 + wp = w2

Signal

/w2

Tapping AFM-IR: Key features

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• Broad Application range:

- Hard/soft sample, Adhesives, Membranes, Particulates

- Minimal sample/tip degradation due to absence of lateral forces

• Improved Sensitivity:

- Sensitivity enhanced by cantilever Q-factor – new probes

- AFM detector with higher sensitivity

- Efficient optical beam delivery optics with minimal loss

• High Spatial Resolution:

- Spatial resolution extends to ~10 nm or better

• Multimodal Imaging:

- Simultaneous chemical and viscoelastic property (Tapping Phase) imaging

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Tapping AFM-IR: ApplicationsPolymer 01: PEMA/PMMA Blend

Tapping IR Image at 1026 cm-1

PEMA

PMMA

Tapping AFM-IR Spectra Height

Sample courtesy: University of Minnesota

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Tapping AFM-IR: ApplicationsPolymer 02: PS/PMMA block copolymer

Sample courtesy: CEA-Leti

2 x 2 um2

Height

HeightTapping IR Image

at 1730 cm-1

5 nm

Tapping AFM-IR image at1730 cm-1 highlights PMMAspheres embedded in PSmatrix

Observed spatial resolution ~5 nm

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Tapping AFM-IR: ApplicationsBio-pharmaceuticals 01: Skin/Dexamethasone

- Tapping AFM-IR image ratio at 1456/1740 cm-1

highlights the relative abundance of the drug in the lipophilic regions

(bright yellow)

Optical

1456

15321660

-CH2 bending

Present in both drug and

long chain lipids1740

Ester C=O

in the

lipids

Amide I & II bands

from Proteins

Height IR Image Ratio

1456/1740

Sample courtesy: FU Berlin

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Tapping AFM-IR: ApplicationsBio-pharmaceuticals 02: Anti-cancer drug delivery

Centrone et al., Analyst, 2018, 143, 3808-3813

• Paclitaxel, a power anti-cancerdrug, suffers from low efficacyand side effects due to low watersolubility/recrystallization

• Recent study by Centrone andcoworkers highlights the use ofTapping AFM-IR technology toexplore the effect of differentencapsulations in drug delivery

• High resolution compositionalsensitivity of this techniqueunfolds new developments oflipid-polymer hybrid films in drugdelivery applications

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Tapping AFM-IR: ApplicationsOrganic Photovoltaics: TQ1/PC70BM Blend

Height

IR Image Ratio

1598/1738

Donor (TQ1 polymer)

Acceptor (PC70BM)

- Tapping AFM-IR spectra and imageshighlights the polymer rich matrix and PC70BMrich domains

Sample courtesy: Karlstad University

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Tapping AFM-IR: Applications2D Materials: Graphene/Graphene Oxide

Manuscript in prepLiu et al., Carbon, 2018, 127, 141-148

- Tapping AFM-IR spectra and imagesshow sensitivity to monolayer Grapheneand Graphene Oxide

Surface

Plasmon

Polariton

(SPP)

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Tapping AFM-IR: ApplicationsFailure Analysis: Organic Nanocontaminations

Tapping AFM-IR

Spectra

FTIR Library Search

“…Knowing why devices fail is a must

when designing next-generation

products..”

V. Lakshminarayanan

www.rfdesign.com, 2011

• AFM-IR technology complementstraditional analytical tools used for failureanalysis in nanoscale semiconductordevices/architectures

• Enhanced sensitivity extends to sampleswith thickness <20 nm

• Tapping AFM-IR technology demonstratespositive identification of nanoscale organiccontaminants on Silicon wafer

Tapping AFM-IR Measurementson nanocontaminant sample

• Tapping AFM-IR spectra show absorption bands consistent with earlier measurements performed onsite – contamination is most likely synthetic polyester (PET/PBT)

• IR signal sensitivity goes down to 3 nm thick residue (bright green)

• Each spectrum is an average of 5 measurements, NOT smoothed

25 nm

35 nm27 nm

18 nm12 nm

5 nm 3 nm

Sample Thickness1730

1264

1242

11001020

35 nm

Heig

ht

Tapping AFM-IR of a Biological Membrane

Wavenumber (cm-1)

mm

Polymeric Nanoparticles for drug delivery

PLA

PLGAantibiotic

PVA

Antibiotic = pipemidic acid

FTIR spectra of products

AFM-IR contact modeTapping AFM-IR

Mapping at 1760 cm-1 center on ester carbonyl band of PLA

PLA/PVA nanoparticle

Polymeric Nanoparticles for drug delivery

PLA/PVA nanoparticle

Mapping at 1425 cm-1 center on absorption band of PVA

Polymeric Nanoparticles for drug delivery

PLGA/PVA nanoparticles with antibiotic

topography

@1640 cm-1

@1425 cm-1

@1415 cm-1

Benefits of Tapping AFM-IR approach

• Better spatial resolution/softer samples via tapping AFM

• Improved chemical imaging via heterodyne detection

• Insensitive to non-local background forces

• Material selectivity via resonance tuning

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Complementary: AFM-IR and s-SNOMscattering scanning nearfield optical microscopy

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s-SNOMAFM-IR

Thermal expansion proportional

to absorption and thermal

expansion coefficients

Scattered light depends on

complex optical constants

Sensitivity of AFM-IR and s-SNOM

0.00

0.20

0.40

0.60

0.80

1.00

1.20

AFM-IR signalstrength

Organics Inorganics

s-SNOM: complex optical property

Metal coated tip acts like an antenna to enhance and localize the light.

Spatial resolution: tip radius 10~20 nm

Eb

Previous: Spatio-spectral Imaging & Broadband Spectroscopy

J. Am. Chem. Soc., 2013, 135, 18292

Proc. Natl. Acad. Sci. 111, 7191 (2014)

Disadvantages: slow, limited

spectral resolution

Disadvantages: can’t do

narrowband imaging (e.g. for

compositional mapping)

Spatio-spectral Imaging Broadband Spectroscopy

sSNOM 1580cm-1 sSNOM 1600cm-1AFM height

2um

2µm

Application: Fano-resonance Bilayer Graphene

Graphene 2, 38727 (2013)

s-SNOM with a broadband laser source

700

757

s-SNOM spectrum of polystyrene below 800 cm-1

SNOM

phase spectrum

FTIR

spectrum

15

μm

nanoIR Laser Options

• AFM-IR lasers (Pulsed tunable OPO & QCL) can provide both spectroscopy & wavelength specific imaging

• Only CW/P QCL (tunable) lasers provide spectroscopy & wavelength specific imaging for s-SNOM

• nanoFTIR lasers only provide spectroscopy & imaging capabilities (AFM-IR&s-SNOM)

4000800 1800 2700 3600

C-H, OH, N-H

Stretch region

FASTspectra QCL

(w/Hyperspectral)

Fast OPO

Hyperspectral QCL

1950

1900

2800 3600

800 1800

4000

Nano FTIR - Advanced

OPO/DFG

POINTSpectra

CW/Pulse QCL laser

600

950

CO2 – 10.6um 943

650 20004000

Mid-IR range

Wavenumber(cm-1)

Fingerprint

Region

Triple Bonds &

conjugated bonds

2000 2300

1900950

Additional Applications – from 2017-2018 publications

• Life Science

• Recent paper in Cell – Simone Ruggeri, Tuomas Knowles (Cambridge)

• AFM-IR in Fluid – Andrea Centrone (NIST)

• Malaria Infected Red Blood Cells – Bayden Wood (Monash)

• In vivo AFM-IR of Bacteria – Bayden Wood (Monash)

• Materials Science

• Deuterium-labeled polyolefin copolymer blend - Dow

• Core/Shell effect in electrospun PHB copolymer fibers – Delaware

• Functionalized graphene - Manchester

• h-BN – Photothermal AFM-IR of 2D Materials - Harvard

• Geoscience - Schlumberger & USGS

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Additional Applications (continued)

• Atmospheric Aerosols – Mark Banaszak Holl (Michigan/Monash)

• Polarized AFM-IR – Karsten Hinrichs (ISAS)

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Summary

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• Unmatched sensitivity for nanoIR spectroscopy & chemical imaging

• <10nm resolution chemical imaging

• Point spectroscopy in 1-2 secs

• HYPERspectral imaging/Spectroscopy for robust statistical analysis

• Easy to use, high performance AFM imaging with improved noise and sensitivity

Recent Technological Advancements in nanoscale IR Technology offers

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