Abstract
Nanoscale topological imaging using atomic force microscopy (AFM) combined with infrared (IR) spectroscopy (AFM-IR) is a rapidly emerging modality to record correlated structural and chemical images. Although the expectation is that the spectral data faithfully represents the underlying chemical composition, the sample mechanical properties affect the recorded data (known as the probe-sample-interaction effect). Although experts in the field are aware of this effect, the contribution is not fully understood. Further, when the sample properties are not well-known or when AFM-IR experiments are conducted by nonexperts, there is a chance that these nonmolecular properties may affect analytical measurements in an uncertain manner. Techniques such as resonance-enhanced imaging and normalization of the IR signal using ratios might improve fidelity of recorded data, but they are not universally effective. Here, we provide a fully analytical model that relates cantilever response to the local sample expansion which opens several avenues. We demonstrate a new method for removing probe-sample-interaction effects in AFM-IR images by measuring the cantilever responsivity using a mechanically induced, out-of-plane sample vibration. This method is then applied to model polymers and mammary epithelial cells to show improvements in sensitivity, accuracy, and repeatability for measuring soft matter when compared to the current state of the art (resonance-enhanced operation). Understanding of the sample-dependent cantilever responsivity is an essential addition to AFM-IR imaging if the identification of chemical features at nanoscale resolutions is to be realized for arbitrary samples.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 8845-8855 |
| Number of pages | 11 |
| Journal | Analytical chemistry |
| Volume | 90 |
| Issue number | 15 |
| DOIs | |
| State | Published - Aug 7 2018 |
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ASJC Scopus subject areas
- Analytical Chemistry
Cite this
Probe-Sample Interaction-Independent Atomic Force Microscopy-Infrared Spectroscopy : Toward Robust Nanoscale Compositional Mapping. / Kenkel, Seth; Mittal, Anirudh; Mittal, Shachi; Bhargava, Rohit.
In: Analytical chemistry, Vol. 90, No. 15, 07.08.2018, p. 8845-8855.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Probe-Sample Interaction-Independent Atomic Force Microscopy-Infrared Spectroscopy
T2 - Toward Robust Nanoscale Compositional Mapping
AU - Kenkel, Seth
AU - Mittal, Anirudh
AU - Mittal, Shachi
AU - Bhargava, Rohit
PY - 2018/8/7
Y1 - 2018/8/7
N2 - Nanoscale topological imaging using atomic force microscopy (AFM) combined with infrared (IR) spectroscopy (AFM-IR) is a rapidly emerging modality to record correlated structural and chemical images. Although the expectation is that the spectral data faithfully represents the underlying chemical composition, the sample mechanical properties affect the recorded data (known as the probe-sample-interaction effect). Although experts in the field are aware of this effect, the contribution is not fully understood. Further, when the sample properties are not well-known or when AFM-IR experiments are conducted by nonexperts, there is a chance that these nonmolecular properties may affect analytical measurements in an uncertain manner. Techniques such as resonance-enhanced imaging and normalization of the IR signal using ratios might improve fidelity of recorded data, but they are not universally effective. Here, we provide a fully analytical model that relates cantilever response to the local sample expansion which opens several avenues. We demonstrate a new method for removing probe-sample-interaction effects in AFM-IR images by measuring the cantilever responsivity using a mechanically induced, out-of-plane sample vibration. This method is then applied to model polymers and mammary epithelial cells to show improvements in sensitivity, accuracy, and repeatability for measuring soft matter when compared to the current state of the art (resonance-enhanced operation). Understanding of the sample-dependent cantilever responsivity is an essential addition to AFM-IR imaging if the identification of chemical features at nanoscale resolutions is to be realized for arbitrary samples.
AB - Nanoscale topological imaging using atomic force microscopy (AFM) combined with infrared (IR) spectroscopy (AFM-IR) is a rapidly emerging modality to record correlated structural and chemical images. Although the expectation is that the spectral data faithfully represents the underlying chemical composition, the sample mechanical properties affect the recorded data (known as the probe-sample-interaction effect). Although experts in the field are aware of this effect, the contribution is not fully understood. Further, when the sample properties are not well-known or when AFM-IR experiments are conducted by nonexperts, there is a chance that these nonmolecular properties may affect analytical measurements in an uncertain manner. Techniques such as resonance-enhanced imaging and normalization of the IR signal using ratios might improve fidelity of recorded data, but they are not universally effective. Here, we provide a fully analytical model that relates cantilever response to the local sample expansion which opens several avenues. We demonstrate a new method for removing probe-sample-interaction effects in AFM-IR images by measuring the cantilever responsivity using a mechanically induced, out-of-plane sample vibration. This method is then applied to model polymers and mammary epithelial cells to show improvements in sensitivity, accuracy, and repeatability for measuring soft matter when compared to the current state of the art (resonance-enhanced operation). Understanding of the sample-dependent cantilever responsivity is an essential addition to AFM-IR imaging if the identification of chemical features at nanoscale resolutions is to be realized for arbitrary samples.
UR - http://www.scopus.com/inward/record.url?scp=85049262091&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85049262091&partnerID=8YFLogxK
U2 - 10.1021/acs.analchem.8b00823
DO - 10.1021/acs.analchem.8b00823
M3 - Article
C2 - 29939013
AN - SCOPUS:85049262091
VL - 90
SP - 8845
EP - 8855
JO - Analytical Chemistry
JF - Analytical Chemistry
SN - 0003-2700
IS - 15
ER -