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This chapter presents the basic designs and working principles of STM and AFM, as well as an elementary theory of tunneling and the imaging mechanism of atomic resolution. Three elementary theories of tunneling are presented: the one-dimensional Schrödinger's equation in vacuum, the semi-classical approximation, and the Landauer formalism. The relation between the decay constant and the work function, and a general expression of tunneling conductance versus tip-sample distance are derived. A brief summary of experimental facts on the mechanism of atomic resolution STM and AFM is presented, which leads to a picture of interplay between the atomic states of the tip and the sample, as well as the role of partial covalent bonds formed between those electronic states. As an introduction to the concept of equivalence of tunneling and atomic forces, atom and molecule manipulation is briefly presented.

This chapter discusses atomic force microscopy (AFM), focusing on the methods for atomic force detection. Although the force detection always requires a cantilever, there are two types of modes: the static mode and the dynamic mode. The general design and the typical method of manufacturing of the cantilevers are discussed. Two popular methods of static force detection are presented. The popular dynamic-force detection method, the tapping mode is described, especially the methods in liquids. The non-contact AFM, which has achieved atomic resolution in the weak attractive force regime, is discussed in detail. An elementary and transparent analysis of the principles, including the frequency shift, the second harmonics, and the average tunneling current, is presented. It requires only Newton's equation and Fourier analysis, and the final results are analyzed over the entire range of vibrational amplitude. The implementation is briefly discussed.

This chapter focuses on the two experimental techniques — the surface force apparatus (SFA) and the atomic force microscope (AFM) — that are commonly used for measuring molecular level forces that act between two surfaces at small separation distances. The first part of this chapter covers the fundamental principles of SFA and AFM design. The second half of this chapter illustrates the application of AFM to measuring surface forces with examples the measurement of van der Waals forces, meniscus forces from liquid films and from capillary condensation, and electrostatic double-layer forces.

Valiant attempts were made to increase the resolution of acoustic microscopy by employing ever higher frequencies and ever less attenuating coupling fluids. But this did not prove the ultimate way to resolution, which was achieved instead by abandoning the concept of focusing to a diffraction‐limited spot, and instead adopting a scanning probe to give near‐field resolution. In the ultrasonic force microscope (UFM), excitation is fed through the sample to the contact with the tip of an atomic force microscope (AFM). Modulation of the ultrasonic excitation is detected through the non‐linear stiffness of the tip–sample contact, which acts as a mechanical diode. The technique can be used for a wide range of materials characterization, for both soft materials such as polymers and stiff materials such as semiconductor nanostructures. In each case UFM gives contrast from the mechanical properties and structure, with resolution of a few nanometres or better. Variations of the technique, such as the heterodyne force microscope (HFM), enable phase resolution on a nanosecond timescale to be combined with stiffness measurement with nanometre spatial resolution.

This chapter starts chronologically with the first measurement, by means of a torsion pendulum, in the recent phase of Casimir force experiments. Then the main breakthroughs in the measurement of the Casimir force between metallic surfaces are presented. One of them was the first demonstration of corrections to the Casimir force due to the nonzero skin depth and surface roughness by means of an atomic force microscope. Another breakthrough was a series of precise indirect measurements of the Casimir pressure by means of a micromechanical torsional oscillator. These measurements allowed a definitive choice between different theoretical approaches to the thermal Casimir force for real metal surfaces. Many other experiments performed in the last few years are also presented, specifically one measurement using the configuration of two parallel plates. The chapter ends with a brief discussion of proposed experiments using metallic surfaces.

All matter, from the simplest fluid such as gaseous helium to the most complex system like a biological cell, is made of electrons and nuclei. Electric potentials tend to glue the nuclei together, while kinetic energy, connected to atomic (nuclear) masses moving with given velocities, tends to pull them apart. It is this eternal struggle between electricity and temperature that ultimately gives rise to the entire world as we see it, with its properties and its changes. This chapter focuses on the analysis and simulation of the phase equilibria, phase changes, and mesophases of molecules using a variety of methods such as light scattering, calorimetry, chemical spectroscopy, X-ray scattering and diffraction, electron micrography and atomic force microscopy, and evolutionary molecular simulation. The basic thermodynamic functions are discussed, along with melting, solid–liquid equilibrium and nucleation from the melt, vapor–liquid and vapor–solid equilibrium, glasses, liquid crystals, nucleation and growth from solution, crystal growth and morphology, and prediction of crystal faces, attachments, energies, and morphology.

Scanning probe microscopy (SPM) scans a fine tip close to a surface and measures the tunneling current (STM) or force (SFM), based on many possible tip-surface interactions. STM provides atomic resolution imaging, or the local electronic structure (spectroscopy) as a function of bias voltage, and is also used to manipulate adsorbed atoms on a clean surface. STM operates in two modes— constant current or height—and requires a conducting specimen. SFM uses a cantilever (force sensor) to measure short range (< 1 nm) chemical, and a variety of long-range (< 100 nm) forces, depending on the tip and the specimen; a conducting specimen is not required. In static mode, the tip height is controlled to maintain a constant force, and measure surface topography. In dynamic mode, changes in the vibrational properties of the cantilever are measured using frequency, amplitude, or phase modulation as feedback to control the tip-surface distance and form the image. Dynamic imaging includes contact and non-contact modes, but intermittent contact or tapping mode is common. SPMs measure properties (optical, acoustic, conductance, electrochemical, capacitance, thermal, magnetic, etc.) using appropriate tips, and find applications in the physical and life sciences. They are also used for nanoscale lithography.

This chapter focuses on the two experimental techniques—the surface force apparatus (SFA) and the atomic force microscope (AFM)—that are commonly used for measuring molecular level forces that act between two surfaces at small separation distances. The first part of this chapter covers the fundamental principles of SFA and AFM design. The second half of this chapter illustrates the application of AFM to measuring surface forces with examples the measurement of van der Waals forces, atomic level repulsive forces, frictional forces, electrostatic double-layer forces, and meniscus forces from liquid films and from capillary condensation.

This chapter introduces some important aspects of the physics of the cell membrane. After a short presentation of the biological facts the chapters shows how the elasticity of the lipid bilayer membrane can be described in the framework of a two-dimensional surface model. Equilibrium shapes of the membrane are governed by a nonlinear partial differential equation and depend on elastic material constants. The atomic force microscope is presented as one experimental tool which can be used to determine these constants locally. The chapter concludes with a discussion of multi-component membranes and their segregation into domains (‘rafts’). In particular, questions of the stability of these inhomogeneous systems are discussed in the same framework as the two-dimensional surface model, and finally they are compared to experiments.

This chapter presents the basic designs and working principles of STM and AFM, as well as an elementary theory of tunneling and the imaging mechanism of atomic resolution. Three elementary theories of tunneling are presented: the one-dimensional Schrödinger’s equation in vacuum, the semi-classical approximation, and the Landauer formalism. The relation between the decay constant and the work function, and a general expression of tunneling conductance versus tip-sample distance are derived. A brief summary of experimental facts on the mechanism of atomic resolution STM and AFM is presented, which leads to a picture of interplay between the atomic states of the tip and the sample, as well as the role of partial covalent bonds formed between those electronic states. Four illustrative applications are presented, including imaging self-assembed molecules on solid-liquid interfaces, electrochemical STM, catalysis research, and atom manipulation.

This chapter reviews the variety of analytical methods used in the investigation and characterization of molecular solids in general, and varieties of crystal forms in particular. The fundamental principles of each technique are described, followed by the specific applications for recognizing and distinguishing crystal forms. Illustrative examples from the current literature are given. The analytical techniques covered include optical/hot stage microscopy, thermal methods (e.g., DSC, TGA, DTA), X-ray crystallography (powder [XRPD], single crystal), infrared spectroscopy (FTIR), Raman spectroscopy, solid sate nuclear magnetic resonance spectroscopy (SSNMR), scanning electron microscopy, atomic force microscopy (AFM), scanning tunnelling microscopy (STM), and density measurements. The chapter closes with a discussion of the development of instrumentation combining these techniques and questions to be answered in determining if two samples are the same or different crystal forms.

This chapter discusses atomic force microscopy (AFM), focusing on the methods for atomic force detection. Although the force detection always requires a cantilever, there are two types of modes: the static mode and the dynamic mode. The general design and the typical method of manufacturing of the cantilevers are discussed. Two popular methods of static force detection are presented. The popular dynamic-force detection method, the tapping mode is described, especially the methods in liquids. The non-contact AFM, which has achieved atomic resolution in the weak attractive force regime, is discussed in detail. An elementary and transparent analysis of the principles, including the frequency shift, the second harmonics, and the average tunneling current, is presented. It requires only Newton’s equation and Fourier analysis, and the final results are analyzed over the entire range of vibrational amplitude. The implementation is briefly discussed.

This chapter finds that the commercialization of scanning tunnelling microscope (STM) and atomic force microscopy (AFM) has played a key role in the widespread use of these instruments in different disciplines and industries. Commercialization has also played a key role in establishing probe microscopy as a key component of nanotechnology research. It has resulted in easy availability and widespread use of these instruments in conducting research on nanotechnology within different industries and disciplines. Several STM and AFM companies have also played a key role in ensuring the widespread use of probe microscopy among other users who used to rely on different instruments to carry on research in respective fields.

Chapter 4 deals with the analytical methods for the characterization of solid forms, including optical and hot stage microscopy, thermal methods (differential scanning calorimetry, thermal gravimetric analysis, etc.), X-ray diffraction methods (powder and single crystal methods), infrared and Raman spectroscopy, solid state nuclear magnetic resonance spectroscopy, electron microscopy, atomic force microscopy, scanning tunneling microscopy, and pycnometry (density measurements). The principles of each of these techniques are outlined, followed by representative examples of their application in the investigation and characterization of polymorphic systems. The integration of a number of analytical tools—“hyphenated techniques”—into a particular instrument is described for a number of cases, followed by a discussion of the experimental approach for determining if two samples comprise polymorphs of the same compound.

Some widely used techniques for the direct physical investigation of the structure of adsorbed surfactant films are introduced. Neutron reflection has yielded very detailed information about adsorbed surfactant films, although it is not readily accessible to many researchers. There are however commercial instruments available for a number of other techniques which are to be found in numerous laboratories. Scanning probe microscopies (STM and AFM) are capable of producing quite remarkable images of surfactant layers on solids and clearly show how surfactants form aggregates at surfaces. Ellipsometry is capable of yielding adsorbed layer thickness and refractive index from which composition with respect to solvent and surfactant can be deduced. The quartz crystal microbalance (QCM) and its variant, QCM-D, can give adsorbed amounts (including hydration in aqueous systems). Brewster angle microscopy (BAM) is a useful tool for the visualization of phase behaviour in surfactant films.

The concept of wavefunction was introduced in the first 1926 paper by Erwin Schrödinger as the central object of the atomic world and the cornerstone of quantum mechanics. It is a mathematical representation of de Broglie’s postulate that the electron is a material wave. It was defined as everywhere real, single-valued, finite, and continuously differentiable up to the second order. Nevertheless, for many decades, wavefunction has not been characterized as an observable. First, it is too small. The typical size is a small fraction of a nanometer. Second, it is too fragile. The typical bonding energy of a wavefunction is a few electron volts. The advancement of STM and AFM has made wavefunctions observable. The accuracy of position measurement is in picometers. Both STM and AFM measurements are non-destructive, which leaves the wavefunctions under observation undisturbed. Finally, the meaning of direct experimental7 observation and mapping of wavefunctions is discussed.

This chapter explains that the field of domain wall (DW) nanoelectronics is predicated on the premise that the distinct physical properties of domain walls offer new conceptual possibilities for devices. It first deals with basic physics of domain wall properties, and in particular the cross-coupling that allows domain walls to display properties and order parameters different from those of the parent bulk material. The chapter then turns to scanning probe techniques for measuring some of these domain wall properties, and specifically atomic force microscopy (AFM). Together with transmission electron microscopy, AFM is one of the most important tools currently available to probe and manipulate the individual position and physical properties of domain walls. Finally, the chapter focuses on two recent developments that allow investigating hitherto overlooked properties of domain walls: their magnetotransport and their mechanical response.