Spectroscopic Methods for Nanomaterials Characterization

Sabu Thomas, Raju Thomas, Ajesh K Zachariah, Raghvendra Kumar Mishra, Sabu Thomas, Raju Thomas, Ajesh K Zachariah, Raghvendra Kumar Mishra, Raghvendra Kumar

• Publisher: Elsevier
• Year: 2017
• Print ISBN: 9780323461405
• eBook ISBN: 9780323461467
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

Nanomaterials Characterization Techniques, Volume Two, part of an ongoing series, offers a detailed analysis of the different types of spectroscopic methods currently being used in nanocharacterization. These include, for example, the Raman spectroscopic method for the characterization of carbon nanotubes (CNTs). This book outlines the different kinds of spectroscopic tools being used for the characterization of nanomaterials and discusses under what conditions each should be used. The book is intended to cover all the major spectroscopic techniques for nanocharacterization, making it an important resource for both the academic community at the research level and the industrial community involved in nanomanufacturing. - Explores how spectroscopy and X-ray-based nanocharacterization techniques are applied in modern industry - Analyzes all the major spectroscopy and X-ray-based nanocharacterization techniques, allowing the reader to choose the best for their situation - Presents a method-orientated approach that explains how to successfully use each technique

Chapter 1

Atomic Force Microscopy as a Nanoanalytical Tool

Rameshwar Adhikari^1,2, Sven Henning³, and Goerg H. Michler^{4 1}Tribhuvan University, Kathmandu, Nepal ²Nepal Polymer Institute (NPI), Kathmandu, Nepal ³Fraunhofer Institute for Microstructure of Materials and Systems (IMWS), Halle/Saale, Germany ⁴Martin Luther University Halle-Wittenberg, Halle/Saale, Germany

Abstract

Atomic force microscopy (AFM), also commonly known as scanning force microscopy, has evolved as an extremely useful tool for the study of the structure and properties of nanostructured systems including nanoparticles (NPs), composites, and soft matters such as polymers and biological tissues. In particular, AFM serves as an excellent complement to electron microscopic techniques, on one hand, and represents a unique tool to study the physical and functional properties of heterogeneous systems on the nanoscale on the other. The aim of this chapter is to elucidate the contribution of AFM to the structural characterization of nanomaterials with an introduction to the principles of the basic AFM techniques and sample preparation methods. A comparison with electron microscopy will also be presented, selecting some illustrative examples of imaging of NPs, soft matter, and composites. We demonstrate that AFM can conveniently be used not only to image the morphology of the materials with nanometer resolution but also to gain insight into the manipulation of the NPs in a controlled manner.

Keywords

Atomic force microscopy; Electron microscopy; Morphology; Nanocomposite; Nanoparticles; Tapping mode

Chapter Outline

1.1 Introduction

1.2 Specimen Preparation

1.2.1 Thin Films

1.2.2 Physical and Chemical Etching, Ion Etching

1.2.3 Ultramicrotomy

1.3 Typical Examples of Nanomaterials Characterization by Atomic Force Microscopy

1.3.1 Nanoparticles Imaging and Manipulation

1.3.2 Biobased Nanomaterials and Nanoencapsulation

1.3.3 Comparison With Electron Microscopy

1.4 Concluding Remarks

Acknowledgments

References

1.1. Introduction

As the development of new materials has played a considerable role in the advancement of human civilization, microscopic techniques have offered probably the most important contribution toward the development of the new materials themselves. The microscope delivers the most direct information on the structure and properties of materials on different length scales, not only allowing the experimentalist to interpret the correlation between very internal structures of the materials and their properties but also permitting the innovator to design new structures relevant for targeted specific applications. In this regard, the electron microscope, and more recently the scanning probe microscope (SPM), have been developed as reliable tools for the characterization of nanomaterials. It should be noted that different scattering techniques, in particular the X-ray methods, have made significant contributions to the understanding of the structure–property correlations of the materials, although the information is averaged over a large volume. An SPM not only can access the structure of materials in the macroscopic to nanoscale range but also studies various phenomena such as adhesion, friction, electrical, magnetic, mechanical, and thermal properties of the materials on a very local level.

Owing to their ability to offer nanoscale resolution and versatile applicability, SPM techniques have emerged as an indispensable nanomaterials characterization tool. The invention of the first atomic force microscope by Binnig and its introduction by Binnig et al. [1,2] in 1986 opened up the possibility of obtaining surface images with atomic resolution on conductors and insulators by utilizing very small tip–sample interaction forces. Thus, among the SPM techniques, the AFM is a highly versatile and popular nanoanalytical tool. Thus, it has been common practice in past decades to supplement electron microscopy with the AFM.

A brief survey of the fundamentals and relevant applications of this technique in nanomaterials research is presented in this chapter. For a detailed account of the fundamentals and application of AFM techniques applied to different materials, the readers may consult more concise reviews [3–7].

In atomic force microscopy, the solid surfaces are scanned in a raster pattern by an extremely sharp mechanical probe attached to a cantilever. Highly localized tip–sample interaction forces are measured as a function of the specimen's local position. In its basic function, AFM provides high-resolution imaging of the surface relief of the specimen between lateral scales of a few nanometers to about a hundred micrometers as demonstrated by some examples presented in Fig. 1.1.

Fig. 1.1 presents tapping-mode AFM images of different magnifications of thin isotactic polypropylene (iPP) film sandwiched between polystyrene (PS) layers prepared by the microlayer coextrusion technique [8–10]. The most popular AFM mode of operation is the so-called “tapping” mode or “intermittent-contact” mode, in which the sample is scanned with an oscillating probe. The contrast mechanism in the AFM operation is based on the local mechanical properties of the specimen [11–14].

Figure 1.1 Tapping-mode atomic force microscopy images of different magnifications of isotactic polypropylene illustrating the surface topography (A and C) and phase morphology (B and D), showing the ability of the technique to image structural details at different length scales.

The images on the top in Fig. 1.1 show the so-called “spherulitic” texture of the iPP with a sphere diameter of a few micrometers, which is not fully grown due to quenching of the samples during processing. The height images are particularly helpful to illustrate the spherulitic texture and surface topography of the sample. A portion of Fig. 1.1A and B is magnified in Fig. 1.1C and D, respectively. The height image (Fig. 1.1C) still preserves information on the surface topography of the specimen, whereas the nanostructured surface morphology of the specimen with cross-hatched crystalline lamellae is visible in the phase image (Fig. 1.1D). By using image processing software, which is usually made available by the atomic force microscope manufacturer, or by using common image processing tools, the morphological details of the specimens can be easily evaluated. In the given case, the thickness of bright-appearing crystalline lamellae in the iPP sample can be measured as being about 10 nm, whereas the interlamellar distance is about 15 nm.

Thus, by using the single probe, the morphological details including microscopic structure as well...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• List of Contributors
• Editor Biographies
• Chapter 1. Atomic Force Microscopy as a Nanoanalytical Tool
• Chapter 2. Electrochemical Characterization
• Chapter 3. Ultraviolet Spectroscopy: A Facile Approach for the Characterization of Nanomaterials
• Chapter 4. Fourier Transform Infrared Spectroscopy
• Chapter 5. Raman Spectroscopy
• Chapter 6. High-Vacuum Tip-Enhanced Raman Spectroscopy
• Chapter 7. Confocal Raman Spectroscopy
• Chapter 8. Inductively Coupled Plasma Mass Spectrometry
• Chapter 9. Electromagnetic Characterization of Materials by Vector Network Analyzer Experimental Setup
• Chapter 10. Dielectric Spectroscopy
• Chapter 11. Dielectric and Magnetic Loss Behavior of Nanooxides
• Chapter 12. Mössbauer Spectroscopy: Basic Principles and Practical Guide to Exotic Mössbauer Isotopes
• Chapter 13. Nuclear Magnetic Resonance Spectroscopy
• Index