Nanoscale IR spectroscopy or AFM-IR spectroscopy is type of hyphenated techniques in the field of analytical chemistry where it is useful for both chemical and structural analysis of the compound with resolution at Nano level. It combines the advantages of the microscope with spectral characteristics of IR spectroscopy. We can Correlate microscopy with spectroscopy and can interpret the data to FTIR also.

1. By
Bunga Sirisha
M. Pharmacy
Maharajah’s college of pharmacy
NANO SCALE IR SPECTROSCOPY
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2. CONTENTS
A. Introduction
B. History
C. Why Nano-IR?
D. Principle
E. Instrumentation
F. Sample preparation
G. Typical work flow of AFM-IR
H. Advantages
I. Disadvantages
J. Applications
K. AFM-IR vs IR
L. Case studies
M. Companies using Nano-IR
N. Generations of Nano-IR
O. References
2

3. INTRODUCTION
 Also called as AFM-IR spectroscopy / NANO IR spectroscopy.
 Combines the efficiency of AFM ( Atomic force microscopy) with the IR
spectroscopy at NANO level to characterize the samples. [1]
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4. HISTORY
 Introduced: Dr. Alexandre Dazzi in 1990
 Practically proved: Hammiche in 1999
 1st experiment: Anderson in 2000 [2]
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5. WHY DO WE NEED NANO IR SPECTROSCOPY?
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o AFM: To measure the topography, mechanical, thermal, electrical, mechanical
properties of the samples at nano scale.
o IR: To determine the chemical composition of the samples
o AFM-IR: To determine the chemical composition and thermal properties with
the help of AFM tip at nano scale spatial resolution. [3]

6. PRINCIPLE
Cantilever/AFM tip oscillation amplitude ~ IR absorption coefficient
 When IR radiation falls on the sample that heats the sample and makes the
sample to expand.
 This thermal expansion is detected by the tip of the cantilever which oscillates
upon the physical changes of samples.
 The oscillations are detected by the photodiode detector. [4]
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8. Cantilever/AFM tip oscillation amplitude ~ IR absorption coefficient
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9. INSTRUMENTATION
 IR source
 Prism
 Cantilever and tip (AFM Tip)
 Laser
 Quadrant photo diode detector[4]
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AFM-IR by ANASYS 2nd generation [8]

12. SAMPLE PREPARATION
There are two ways:
o Ultra-micro -tomy: To cut sections with thicknesses between 100 nm and
1000 nm.
o Thin films: With suitable volatile solvents. [5]
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13. WORKING OF THE AFM-IR
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Step 1: The sample is prepared and kept under the microscope.
Step 2: A specific area of interest on the sample is to be selected.
Step 3: The cantilever tip/probe is positioned on the selected area on the sample
and focused using the microscope.
Step 4: The area of the sample gets magnified upon increasing the resolution
capacity of the microscope.
Step 5: The Infra-red radiations are irradiated over the sample area.
Step 6: Due to the heat in the radiations the sample expands which results in
change in the surface parameters.

14. WORKING OF THE AFM-IR
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Step 7: The change in the surface parameter is detected by the tip of the
cantilever.
Step 8: As the change position of the cantilever tip from one position to other
position on the sample the and irradiated with the IR rays the heat gets
absorbed and surface expansion occurs resulting in continuous vibration of the
cantilever tip .
Step 9: A laser is deflected over the cantilever tip towards the detector. These
vibrations are recorded in the form of oscillations.

15. WORKING OF THE AFM-IR
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Step 10: The amplitude can be modified as function of frequency or wave
number. From the frequency of the oscillation at each point of the sample we
determine the chemical composition of the sample at different positions.
Step 11: The amplitude can be modified as function of frequency or wave
number or IR coefficient. From the frequency of the oscillation at each point of
the sample we determine the chemical composition of the sample at different
positions.
Step 12: The graphical data of the AFM-IR from the detector can be modified as
AFM-FTIR data.

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18. ADVANTAGES
 Sample can be analyzed at nano-level {as for IR it is restricted to micro levels}
 3- D imaging of crystal samples.
 Surface roughness information.
 The spectral data can be correlated to FTIR and obtain nano scale FTIR
 10nm resolution and monolayer sensitivity IR chemical imaging
 High speed chemical imaging - 10x faster
 We can also apply for biological membranes.
 Diffraction limit is 100x more compared to IR
 Correlates microscopy with spectroscopy. [7]
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19. DISADVANTAGES
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 The sample preparation is needed to be done properly without any dust or
impurities as the AFM tip is highly sensitive to rough surfaces. [7]

20. APPLICATIONS
 To study the infections of bacteriophages
 To evaluate and map mineral content, crystallinity, collagen maturity and acid
phosphate content in bone.
 To perform spectroscopy and chemical mapping of structural lipids in human
skin and hair.
 The measurements revealed the distribution of free and ionically bound water
on the surface of samples.
 Used to study the surface plasma on resonance in heavily doped indium micro
particles.
 Used to study miscibility and phase separation in drug polymer blends, well as
the chemical analysis of nanocrystalline drug particles as small 90 nm across.
[6]
20

21. IR vs AFM-IR
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CATEGORY IR AFM-IR
Sample preparation Simple and easy Should be done carefully
Analysis Chemical composition
Both chemical composition
and surface analysis
Spectral resolution Low High (100x)
Sample concentration
Can be done from micro
level
Can be done nano level
Time bound More time Less time
3-D imaging No Yes
Data correlation No Can correlate with FTIR[5]

22. CASE STUDY 1: STUDY OF POLYSTYRENE SPHERES
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 Polystyrene is micro-tomes to layers.
 The layer is focused by radiation
 There is an maximum absorption of radiation at 2025cm−1 which corresponds
to the aromatic bonds in the polystyrene. [6]

23.  An AFM image with nano-TA data of a toner particle. The particle was
embedded in epoxy and microtome. The topography of the sample shows
variations in structure, which can then be analyzed using nano-TA. Toner
particles include a number of components (wax, resin, dye, etc.) that exhibit
different transition temperatures. [6]
23
CASE STUDY 2: NANO SCALE THERMALANALYSIS

24. COMPANIES THAT ARE UTILISING THE INSTRUMENT
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COMPANY /LAB PURPOSE OF UTILISATION
Knowles Lab, University Cambridge
Characterization of heterogeneous
biological protein samples.
Laboratory of the Physics of Living Matter,
Switzerland
In the area of protein misfolding and
aggregation.
Laboratory of Polymer Physics and
Chemistry, Japan
Studying polymeric materials.
Dow Chemicals Pvt Ltd, USA Chemistry in the morphology. [7]

25. GENERATIONS OF NANO-IR [8]
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26. REFERENCES
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1. Madey TE, Pelhos K, Wu Q, Barnes R, Ermanoski I, Chen W, Kolodziej JJ,
Rowe JE. Nanoscale Surface Chemistry. Journal of Chemical Society Reviews.
2008; 37(10): 6503-6508.
2. Hu H, Yang X, Zhai F, Hu D, Liu R, Liu K, Sun Z, Dai Q. Far-field Nanoscale
Infrared Spectroscopy of Vibrational Fingerprints of Molecules with Graphene
Plasmons. Journal of Nature communications. 2016; 7(1): 1-8.
3. Prater C, Kjoller K, Shetty R. Nanoscale Infrared Spectroscopy. Journal of Materials
Today. 2010; 13(11): 56-60.
4. Kirpes RM, Merzel RL, Pratt KA, Banaszak Holl MM, Ault AP. Atomic Force
Microscopy-infrared Spectroscopy of Individual Atmospheric Aerosol Particles:
Sub-diffraction Limit Vibrational Spectroscopy and Morphological Analysis.
Journal of Analytical Chemistry. 2017; 89(17): 894-902.

27. REFERENCES
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5. Bondy AL, Kirpes RM, Merzel RL, Pratt KA, Banaszak Holl MM, Ault AP.
Analytical chemistry.4 1st ed. United states. ACS Publications. 2017; 8594-8598.
6. Dazzi A, Prater CB. AFM-IR: Technology and Applications in Nanoscale Infrared
Spectroscopy and Chemical Imaging. 4th ed. United states. ACS Publications.2017;
5146-5173.
7. Bruker Nano Surfaces [cited 28 July 2020]. Available from:
https://www.youtube.com/user/BrukerNanoSurfaces.://www.youtube.com/user/Bruk
er NanoSurfaces.
8. AFMIR Nano Spectroscopy [cited 28 July 2020]. Available from:
https://en.wikipedia.org/wiki/AFMIR #Nano Spectroscopy.

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