Nanochemistry, Plasmonics, and Correlated Imaging … · Nanochemistry, Plasmonics, and Correlated...

Nanochemistry, Plasmonics, and Correlated Imaging

Integrated IR Nanocharacterization with Inspire

Si

PS

PMMA

Inspire – New Capabilities for New Discoveries

2 10/22/2014 Bruker

PS PHBV

• A first of its kind nanoscale mapping system

• Nanochemical properties – from SPIR

• Infrared (IR) reflection and absorption

• 10 nm spatial resolution – 1000x beyond diffraction limit

• Monolayer thickness sensitivity

• Nanomechanical properties – from PeakForce QNM

• Stiffness, adhesion, etc.

• Nanoelectrical properties – from KPFM, SCM

• Work function, conductivity

• With a broad range of applications

• Polymers, thin films, graphene, …

• In an easy to use integrated package

• No additional sample preparation – all AFM samples work!

• Simple, quick, automated optical alignment

• Meaningful results – reflection and absorption

Inspire – unambiguous nanoscale

chemical mapping

3

Spatio-spectral imaging on PS-PMMA polymer:

PS-PMMA blend. Reflection shows material contrast at any frequency. Absorption identifies PMMA on resonance. Here using the 100cm-1 range of a QCL centered at 1730cm-1 to move

on and off the 1736cm-1 carbonyl resonance of PMMA. Image size 4 microns.

Height

Phase

Reflection

Absorption

1759 cm-1

10/22/2014 Bruker

Height

Phase

Reflection

Absorption

1736 cm-1

PS PMMA

4 microns

• Spatio-spectral imaging with a QCL on PS-PMMA polymer:

• Reflection shows material contrast at any frequency

• Absorption shows PMMA C=O stretch on resonance

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Inspire – monolayer sensitivity From graphene to organic semiconductors

500 nm

• Graphene in absorption @ 870 cm-1

3.3um

Max

Min

• Individual pentacene monolayers show up in non-resonant reflection

3D overlay of height and IR reflection @ 1900 cm-1

PeakForce IR

Simultaneous mapping of nanochemistry and quantitative nanomechanics, with the full power of PeakForce QNM.

5

Correlated nanochemical-nanomechanical imaging with PeakForce IR:

LDPE domains in PS matrix. The domains are seen to protrude, have lower modulus, similar adhesion, and be chemically distinct from the matrix. All this information was obtained simultaneously! PeakForce IR combines

SPIR and PeakForce QNM

10/22/2014 Bruker

Approach

Withdraw

Height

Adhesion

Modulus

Chemistry

PS LDPE

1 mm Peak Force QNM:

Please see Jan 2014 AFM webinar for more information:

http://www.bruker.com/service/education-training/webinars/afm.html

Exclusive Measurement Breadth

Combine IR nanochemical mapping with Bruker exclusive electrical measurements including mV level workfunction measurements and conductivity on soft samples.

6

Inspire provides the widest set of

new & exclusive capabilities.

What will you discover?

PeakForce IR:

SPIR imaging, here

shown for graphene at

1730cm-1, showing the

expected layer ordering

in universal

conductivity regime’

PeakForce KPFM

work function imaging with

mV sensitivity, here shown

for reduced graphene

oxide. Revealing <20nm

potential variations due to

chemical heterogeneity.

PeakForce QNM

nanomechanical

imaging with

atomic defect

resolution, shown

here on calcite.

PeakForce TUNA

conductivity imaging,

shown here on

vertically standing

carbon nanotubes.

Impossible with

contact mode.

Height Conductivity

10/22/2014 Bruker

10 nm

750 nm 1 mm

15 mm

Introducing Inspire

7

Introduction to the Technique

PS-PMMA: Absorption at 1730cm-1, 5 micron image.

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Why is infrared spectroscopy useful?

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IR absorption provides chemical

fingerprint + IR light is sensitive

to molecular vibrations, lattice

vibrations, plasmons…

Example: PMMA infrared

spectrum shows absorption lines:

Duan G. et. al. Nanoscale Res. Lett. (2008)

PMMA

polymer

Bruker Tensor

Such spectra can be acquired using Bruker

FTIR instruments such as the Tensor

BUT: Far-field spectroscopy is limited in spatial resolution to ~10 mm

Does not provide simultaneous reflection!

But nanoscale IR imaging is useful!

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Bruker

9

7.5um

7.5um x 7.5um

A.J. Huber et. al. NanoLett 2008

Biology: Tobacco Mosaic Virus

M. Brehm et. al. Nano Lett 2006

Semiconductors

Geology: comet dust

Gainsforth et al. 44th Lunar and

Planetary Science Conference 2013

1mm SEM SNOM

1043cm-1

940cm-1

993cm-1

Polymers

50nm x 50nm

PS-b-P2VP

M. Raschke et. al. ChemPhysChem 2005

BN: phonon polaritons

X. Xu et. al. Nat. Comm. 2014

~2 mm spot

Scattering SNOM = SPIR

(Scanning Probe IR)

implementation in the Inspire

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XYZ

1. IR laser light from

optics box is focused

by a lens onto a

metallized AFM tip

1

2

3

2. AFM engages the

tip and scans a

sample in XYZ

3. IR light focused

on the tip creates

IR near fields in

the tip/sample gap

with field

enhancement

+++

- - -

Interferometer

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XYZ

+++

- - - 7

6 5

5. The tip radiates IR light

a portion of which is

sensitive to the near fields 6. The same

focusing lens

collects the tip’s

radiated IR light

7. The tip’s radiated light

is collimated and directed

to an IR detector in the

optics box

Interferometer


(Scanning Probe IR)


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XYZ

+++

- - - 7

6 5

Interferometer


(Scanning Probe IR)


Localization to ~ 10 nm

(tip radius), independent

of l!

Imaging with

PeakForce QNM,

KPFM, …!

Infrared absorption

and reflection!

MCT Detector Voltage:

Contains nanoscale information

𝑬𝒏𝒇 +𝑬𝒃𝒈 𝑬𝒃𝒈

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𝑬𝒏𝒇 +𝑬𝒃𝒈

Inside the

Interferometer

Piezo-actuated Mirror

SPIR detection

14

𝑉𝑑𝑒𝑡 ∝ 𝐸𝑟𝑒𝑓 𝐸𝑛𝑓 cos 𝜑𝑟𝑒𝑓 − 𝜑𝑛𝑓 + 𝐸𝑏𝑔𝐸𝑛𝑓 cos 𝜑𝑏𝑔 − 𝜑𝑛𝑓 + 𝐸𝑟𝑒𝑓𝐸𝑏𝑔 cos 𝜑𝑟𝑒𝑓 − 𝜑𝑏𝑔

+ 𝐸𝑟𝑒𝑓2 + |𝐸𝑛𝑓|2 + |𝐸𝑏𝑔|2

Isolated at higher harmonics

and amplified by large Eref

Allows phase sensitive

measurement!

Negligible

compared to Eref Suppressed at

higher harmonics

10/22/2014 Bruker

SPIR detection

Tip tapping to extract near-field

information from scattering signal:

height time

FFT 𝑬𝒏𝒇 +𝑬𝒃𝒈

Inside the

Interferometer


15

𝑉𝑑𝑒𝑡 ∝ 𝐸𝑟𝑒𝑓 𝐸𝑛𝑓 cos 𝜑𝑟𝑒𝑓 − 𝜑𝑛𝑓

Isolated at higher harmonics

and amplified by large Eref

Allows phase sensitive

measurement!

10/22/2014 Bruker

SPIR detection

Choose to sample the IR

near field response, 𝑬𝒏𝒇:

Reflection

Absorption

𝜑𝑟𝑒𝑓 = 0

𝜑𝑟𝑒𝑓 = π/2

𝜑𝑟𝑒𝑓

height time

FFT 𝑬𝒏𝒇 +𝑬𝒃𝒈

Inside the

Interferometer


Tip tapping to extract near-field

information from scattering signal:

SPIR with Inspire

Effect of a resonance on Absorption

+++

- - -

On Carbonyl resonance, IR laser ω = 1730cm-1

C=O

Off Carbonyl resonance, IR laser ω = 1760cm-1

+++

- - -

C=O

By measuring “out of phase”

Inspire detects Absorption

with 10nm resolution

Enables nanoscale chemical

identification

16

𝜑𝑟𝑒𝑓 = π/2 𝜑𝑟𝑒𝑓 = π/2

10nm

10/22/2014 Bruker

SPIR with Inspire

Effect of a resonance on Reflection

+++

- - -

On Carbonyl resonance, IR laser ω = 1720cm-1

C=O

Off Carbonyl resonance, IR laser ω = 1760cm-1

+++

- - -

C=O

By measuring “in phase”

Inspire detects Reflection

with 10nm resolution

Information beyond ChemID:

Film Thickness

Conductivity

Plasmonics

17

𝜑𝑟𝑒𝑓 = 0 𝜑𝑟𝑒𝑓 = 0

10nm

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Beyond absorption: reflection spectrum

provides additional information

18

Graphene

Simultaneous reflection AND absorption enables

characterization of virtually any material!

Polymers and other chemicals

10/22/2014 Bruker

reflection

reflection

absorption

absorption

Bruker

50nm x 50nm

324K

328K

Metal-to-insulator transitions

Liu et al. Phys Rev Lett 2013

Introducing Inspire

19

Demonstration of Capabilities

Cross-section of a Glass Optical Fiber :Reflection at 1900cm-1, 5 micron image.

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10nm-resolved IR reflection map

20

10nm spatial resolution:

Resolving 10nm features in IR reflection at 1933cm-1 on Si/SiO2 grating.

10 microns 1 micron 250 nm

10nm

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Simultaneous reflection AND

absorption mapping

• On resonance with IR fingerprint

• IR reflection AND absorption at 10nm resolution

• Simultaneously acquired in tapping mode (or PFT)

21

Reflection Absorption

Height Phase On resonance PMMA PS

2um

C=O

10/22/2014 Bruker

Simultaneous reflection AND

absorption mapping

• Off resonance with IR fingerprint

• Absorption channel disappears

• Reflection channel provides material contrast across entire IR range

22

Reflection Absorption

Height Phase Off resonance PMMA PS

No Contrast.. Contrast..

Reflection channel is less specific but enables

identification over a wider spectral range

2um

C=O

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Inspire – Sensitivity to phase

changing materials

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CD-RW media

Height Reflection

15um

Height

5um

Reflection

DVD-RW media

• Lower reflection reveals amorphous regions

• Topography free contrast demonstrated

PeakForce IR: simultaneous

nanomechanical and optical imaging

24

Height Adhesion

Modulus Deformation

QNM images of PS/LDPE blend

PeakForce IR - the only method for simultaneous, quantitative,

nanomechanical AND nanooptical characterization

Simultaneous IR

10/22/2014 Bruker

PS

Re(rp) ~ 0.12

LDPE

Re(rp) ~ 0.07

IR Reflection

0.04

0.16

Re(rp)

PeakForce IR: simultaneous

nanomechanical, electrical

and optical imaging

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Height

Adhesion

Potential

Reflection

Aluminum Silicon Gold

20um

Height

Potential

Adhesion

Charged Particle?

Reflection

Sample compatibility: equally effective

on Organic or Inorganic samples

26

PS

LDPE

Si

Height IR Reflection

Imaging embedded organic/inorganic materials

Clearly identifying the cross sectioned fiber by its higher reflectivity compared to the matrix and droplets of epoxy. IR reflection at 1900cm-1.

Distinguishing multiple organic

materials and inorganic substrate

Revealing PS matrix, LDPE inclusion, and

exposed Si substrate. IR reflection at 1028cm-1.

Imaging multiple inorganic materials

Showing location of Si vs SiO2 as well as small contamination specks. IR reflection at 1900cm-1.

Si

SiO2

Direct optical mapping, not requiring

photothermal response, no special sample

preparation, works even on samples not

conducive to contact or Tapping mode.

10/22/2014 Bruker

Height

IR Absorption

500 nm

Imaging organic materials

Ps-b-PMMA block copolymer, PMMA shows IR absorption at 1725 cm-1.

7 mm

7 mm

SPIR characterization

of Graphene

27

Reflection

Absorption

2Ef±Γ

Universal

Conductivity Plasmonics

Ef = 700cm-1, Γ = 30cm-1

Carrier density – 2Ef

position

Defects – Γ,

conductivity floor

Number of layers –

universal conductivity

level

Calculated SPIR spectrum of Graphene What does SPIR reveal

about Graphene?

10/22/2014 Bruker

For a description of Graphene’s infrared conductivity see

Z.Q. Li et. al. “Dirac Charge dynamics in graphene by infrared spectroscopy”

SPIR characterization of Graphene

Universal Conductivity regime

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Reflection

Absorption

Calculated SPIR spectrum of Graphene



1730cm-1

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Reflection 1730cm-1

10nm resolution

Reflection image

at 1900cm-1

SiO2 1

2 3

4

AFM

KPFM

~50mV

Inspire: optical characterization of

Graphene in Universal Cond. Regime

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Inspire: optical characterization of

Graphene - defect detection

Nanomechanics shows signs of wrinkles

Hint of

defects in

D-band

Raman

SPIR

reflection

signal

consistent with

higher defect

concentration

2% lower

IR Reflection

1900cm-1

2% lower

SPIR characterization of Graphene

Plasmonic regime

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Reflection

Absorption

Calculated SPIR spectrum of Graphene



870cm-1

SPIR characterization of Graphene Plasmonic regime

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Fei,

Andreev,

Nano Lett.

11, 4701

(2011)

Coupling to high momenta…


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…via nanostructuring

Ju, Nat. Mater.

6, 630 (2011)

Fei,

Andreev,

Nano Lett.

11, 4701

(2011)



10/22/2014 34 Bruker

Fei,

Andreev,

Nano Lett.

11, 4701

(2011)


…via s-SNOM


10/22/2014 35 Bruker

Fei,

Andreev,

Nano Lett.

11, 4701

(2011)


…via s-SNOM

Plasmonic

interfence

Andreev G.O. et. al. APS 2011

Fei Z. et. al. Nature 2012

Chen J. et. al. Nature 2012

Example from scientific literature:


10/22/2014 36 Bruker

500 nm

Refl. Abs

Examples from Inspire

IR 870cm-1

Plasmonic

interfence

Andreev G.O. et. al. APS 2011

Fei Z. et. al. Nature 2012

Chen J. et. al. Nature 2012

Example from scientific literature:

Imaging Graphene plasmons with

market leading scan speeds

• 10Hz image obtained in just 30s

• No significant loss of spatial resolution

• No sample damage

• Impossible without the stability of Bruker AFM technology and near field optical imaging of Inspire

1Hz 4Hz 10Hz

~140nm

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• A first of its kind nanoscale mapping system

• Nanochemical properties – from SPIR

• Infrared (IR) reflection and absorption

• 10 nm spatial resolution – 1000x beyond diffraction limit

• Monolayer thickness sensitivity

• Nanomechanical properties – from PeakForce QNM

• Stiffness, adhesion, etc.

• Nanoelectrical properties – from KPFM, SCM

• Work function, conductivity

• With a broad range of applications

• Polymers, thin films, graphene, …

• In an easy to use integrated package

• No additional sample preparation – all AFM samples work!

• Simple, quick, automated optical alignment

• Meaningful results – reflection and absorption

Inspire – New Capabilities for New Discoveries

38 10/22/2014 Bruker

PS PHBV

Nanochemistry, Plasmonics, and Correlated Imaging … · Nanochemistry, Plasmonics, and Correlated...

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Transcript of Nanochemistry, Plasmonics, and Correlated Imaging … · Nanochemistry, Plasmonics, and Correlated...