http://experimentationlab.berkeley.edu/sites/default/files/AFMImages/butt_AFM.pdf

Force measurements with the atomic force microscope: Technique, interpretation and applications

This article reviews the progress of atomic force microscopy in ultrahigh vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows us to image surfaces of conductors and insulators in vacuum with atomic resolution. The most widely used technique for atomic-resolution force microscopy in vacuum is frequency-modulation atomic force microscopy (FM-AFM). This technique, as well as other dynamic methods, is explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened our theoretical understanding of frequency-modulation atomic force microscopy. Consequently spatial resolution and ease of use have been increased dramatically. Vacuum atomic force microscopy opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.

https://hep.physics.utoronto.ca/WilliamTrischuk/courses/phy189/AFM_revmodphys.pdf

Advances in atomic force microscopy

Dynamic atomic force microscopy methods

During the past decade, enormous progress has been made in growing ultrathin organic films and multilayer structures with a wide range of exciting optoelectronic properties. This progress has been made possible by several important advances in our understanding of organic films and their modes of growth. Perhaps the single most important advance has been the use of ultrahigh vacuum (UHV) as a means to achieve, for the first time, monolayer control over the growth of organic thin films with extremely high chemical purity and structural precision.1-3 Such monolayer control has been possible for many years using well-known techniques such as Langmuir-Blodgett film deposition,4 and more recently, self-assembled monolayers from solution have also been achieved.5 However, ultrahighvacuum growth, sometimes referred to as organic molecular beam deposition (OMBD) or organic molecular beam epitaxy (OMBE), has the advantage of providing both layer thickness control and an atomically clean environment and substrate. When combined with the ability to perform in situ highresolution structural diagnostics of the films as they are being deposited, techniques such as OMBD have provided an entirely new prospect for understanding many of the fundamental structural and optoelectronic properties of ultrathin organic film systems. Since such systems are both of intrinsic as well as practical interest, substantial effort worldwide has been invested in attempting to grow and investigate the properties of such thin-film systems. This paper is a review of recent progress made in organic thin films grown in ultrahigh vacuum or using other vapor-phase deposition methods. We will describe the most important work which has been published in this field since the emergence of OMBD in the mid-1980s. Both the nature of thin-film growth and structural ordering will be discussed, as well as some of the more interesting consequences to the physical properties of such organic thin-film systems will be considered both from a theoretical as well as an experimental viewpoint. Indeed, it will 1793 Chem. Rev. 1997, 97, 1793−1896

Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques.

Regarding the activation of chemical reactions, today’s chemist is used to thinking in terms of thermochemistry, electrochemistry, and photochemistry, which is reflected in the organization and content of the standard physical chemistry textbooks. The fourth way of chemical activation, mechanochemistry, is usually less well-known. The purpose of the present review is to give a survey of the classical works in mechanochemistry and put the key mechanochemical phenomena into perspective with recent results from atomic force microscopy and quantum molecular dynamics simulations. A detailed historical account on the development of mechanochemistry, with an emphasis on the mechanochemistry of solids, was recently given by Boldyrev and Tkáčová.1 The first written document of a mechanochemical reaction is found in a book by Theophrastus of Ephesus (371-286 B.C.), a student of Aristotle, “De Lapidibus” or “On stones”. If native cinnabar is rubbed in a brass mortar with a brass pestle in the presence of vinegar, metallic mercury is obtained. The mechanochemical reduction probably follows the reaction:1-3 * To whom correspondence should be addressed. Telephone: ++49-89-289-13417. Fax: ++49-89-289-13416. E-mail: martin.beyer@ch.tum.de (M.K.B.); Telephone: ++49-89-12651417. Fax: ++49-89-1265-1480. E-mail: clausen-schaumann@ fhm.edu (H.C.-S.). † Technische Universität München. ‡ Institut für Strahlenschutz. § Current address: Munich University of Applied Sciences. HgS + Cu f Hg + CuS (1) Volume 105, Number 8

http://depa.fquim.unam.mx/amyd/archivero/MECANOQUIMICA_3426.pdf

Mechanochemistry: the mechanical activation of covalent bonds.

The conservative and dissipative forces between tip and sample of a dynamic atomic force microscopy (AFM) were investigated using a combination of computer simulations and experimental AFM data obtained by the frequency modulation technique. In this way it became possible to reconstruct complete force versus distance curves and damping coefficient versus distance curves from experimental data without using fit parameters for the interaction force and without using analytical interaction models. A comparison with analytical approaches is given and a way to determine a damping coefficient curve from experimental data is proposed. The results include the determination of the first point of repulsive contact of a vibrating tip when approaching a sample. The capability of quantifying the tip-sample interaction is demonstrated using experimental data obtained with a silicon tip and a mica sample in UHV.

/pdf/conservative-and-dissipative-tip-sample-interaction-forces-4yhgk4xjkx.pdf

Conservative and dissipative tip-sample interaction forces probed with dynamic AFM

A combined STM, LEED and molecular modelling study of PTCDA grown on Ag(110)

Structural evolution of pentacene thin films on Ag(110) crystal, during molecular deposition and during a subsequent change of substrate temperature, was investigated in situ by a molecular beam epitaxy low-energy electron diffraction technique. The pentacene molecules exhibit high mobility on the Ag(110) surface at room temperature and the adsorbate shows a structural evolution from disorder in the submonolayer to an ordered structure when it reaches one monolayer. Heating the substrate to $145\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ results in no further structural transition. The ordered monolayer structure on Ag(110) has two domains mirrored at the crystal axis of the silver substrate. Molecular mechanics calculations indicate that the pentacene molecules lie flat on the Ag(110) surface, which is in good agreement with the experimental results. The calculation also gives the favorable position; i.e., the orientation of pentacene on the Ag(110).

Structural evolution of pentacene on a Ag(110) surface

The influence of molecular aggregation on the device properties of organic light emitting diodes

The growth of perylene and coronene up to a monolayer is investigated continuously by low-energy electron diffraction (LEED) on the metal surfaces Ag(110), Au(110) $1\ifmmode\times\else\texttimes\fi{}2,$ and Au(111) $22\ifmmode\times\else\texttimes\fi{}\sqrt{3}.$ Both molecules show [restricted on Au(110) $1\ifmmode\times\else\texttimes\fi{}2]$ the evolution from isotropic disordered structure in the submonolayer regime to a highly (substrate-dependent) ordered monolayer. Two-dimensional gas, fluid, and crystalline phases can be distinguished. On the rough Au(110) $1\ifmmode\times\else\texttimes\fi{}2$ surface, a periodic structure in the [001] direction can be observed, while in the $[11\ifmmode\bar\else\textasciimacron\fi{}0]$ direction, diffraction patterns arise from diffuse LEED intensity. Just before the monolayer is complete, structural transitions between highly ordered structures occur in all presented adsorbates. Leaving and reaching of commensurate structures show ``stick-slip'' behavior. The lateral ordering process of these molecules allows epitaxial growth without domain walls because crystallization does not start from islands in the submonolayer regime.

C. Seidel

Papers

Conservative and dissipative tip-sample interaction forces probed with dynamic AFM

A combined STM, LEED and molecular modelling study of PTCDA grown on Ag(110)

Structural evolution of pentacene on a Ag(110) surface

The influence of molecular aggregation on the device properties of organic light emitting diodes

Structural transitions of perylene and coronene on silver and gold surfaces: A molecular-beam epitaxy LEED study