The bonding, chemistry and ordering of molecular adsorbates on well defined single crystal surfaces and in ultrathin films was to be studied in an effort to develop sufficient fundamental understanding to allow the controlled preparation of anisotropic ultrathin films of organic monolayers. In this research the authors combine the use of optical probes (Raman spectroscopy, laser induced thermal desorption with Fourier transform mass spectrometry detection) with scanning tunneling microscopy (STM) and conventional methods of UHV surface science (Auger electron spectroscopy, x-ray photoelectron spectroscopy, low energy electron diffraction, and thermal desorption spectroscopy). The conventional surface probes provide well tested methods for the preparation and characterization of single crystal substrates. The optical probes used in the experiments provide powerful methods for the molecular identification of adsorbates in monolayers and ultrathin films. Scanning tunneling microscopy provides one with the ability to determine the detailed molecular level ordering of the molecular adsorbates. The emphasis of this research is on more complex molecular absorbates some of which are monomer precursors to ultrathin polymer films. Enhanced methods of Raman spectroscopy have been developed for the study of monolayer adsorbates on surfaces in ultrahigh vacuum environments. This report gives an overview of recent research results, including the construction of UHV variable temperature STM, analysis of STM images, growth and chemistry of intermetallic single crystal ultrathin films, and electron beam induced chemistry of tetracyanoquinodimethane.

Scanning tunneling microscopy has achieved remarkable progress and become the key technology for surface science. This book predicts the future development for all of scanning probe microscopy (SPM). Such forecasts may help to determine the course ultimately taken and may accelerate research and development on nanotechnology and nanoscience, as well as all in SPM-related fields in the future.

The combination of optical detection system with a scanning tunneling microscope (STM) leads to the possibility of resolving radiative transition probability with the ultrahigh spatial resolution of STM in real space. This opens an innovative approach toward revealing the correlation between molecular structure, electronic characteristics, and optical properties. This thesis describes a series of experiments that manifests this correlation, including atomic silver chains and single porphine molecules. In atomic silver chains, the number and positions of the emission maxima in the photon images match the nodes in the dI/dV images of "particle-in-a-box" states. This surprising correlation between the emission maxima and nodes in the density of states is a manifestation of Fermi's golden rule in real space for radiative transitions, which provides an understanding of the mechanism of STM induced light emission. From single porphine molecules, orthogonal spatial contrast of two types of vibronic coupling is resolved by both photon spectroscopy and vibronic-mode-selected photon images. Intramolecular transitions from the two orthogonal LUMOs individually couple to different molecular normal modes. This is the first demonstration of the photon emission probability of a single molecule and its direct correlations with the molecular orbitals. This also provides the first real space experimental evidence to separate the tangled effects of molecular conformations and nano-environments on the inhomogeneity of molecular emission. DSB molecules are found to have two conformational isomers and one of them shows surface chirality. All these conformers and enantiomers can be switched to each other by electron injection. Different DSB conformers present distinct manipulation dynamics, which demonstrate how different conformations and their preferred adsorption geometries can have pronounced influence on the molecular mechanics on the surface. Overall, this thesis studies the very fundamental nature of single molecules and artificial nanostructures by integrating all kinds of important functions of STM: topography, spectroscopy, manipulation, and photon emission. Detailed correlations between the emission patterns and orbital structures are revealed by the ultimate spatial resolution of our "STM photon microscopy."

On the nanometer scale, the local variation of the electronic density of states of aluminum based complex metallic alloys (quasicrystals and approximants) is experimentally investigated by low temperature scanning tunneling spectroscopy. We report on the correlation between the local variations of the electronic density of states and the electrical resistivity. The surface structure is investigated by scanning tunneling microscopy, low energy electron diffraction, and X-ray photoemission diffraction. Experimental results are interpreted on the basis of the respective bulk structure models.

Scanning tunneling microscopy (STM), photoemission spectroscopy, and a variety of other experimental techniques have been used to examine both the initial stages of interface formation between various adsorbates, as well as, reconstructions occurring on the clean surfaces of Si and Ge. The initial stages of oxidation of the Si(111)-(7 x 7) and Ge(111)-c(2 x 8) surfaces were studied. Images of the same area of each surface were obtained from various exposures of oxygen. On the Si(111)-(7 x 7) surface, the results show that defect sites act as nucleation centers for the oxidation process. On the Ge(111)-c(2 x 8) surface, images of the surface for exposures of oxygen up to 1600 Langmuirs were obtained. The results show that the oxidized portions of the surface grow as islands which expand preferentially in the (112) direction. The "16 structure" and c(8 x 10) reconstructions occurring on the clean Ge(110) surfaces were examined. STM images show that the Ge(110)-"16 structure" reconstructed surface is composed of ordered facets as predicted by a low-energy-electron diffraction study. STM images of the Ge(110)-c(8 x 10) surface show that the unit cell is composed of alternating oblique sub-unit cells. Photoemission spectra of the Ge 3d core levels for both these surfaces show the presence of multiple surface-shifted components. Sb deposition on these surfaces has also been studied. Sb deposition results in the formation of a (1 x 1) or (3 x 2) ordered over-layer depending on the substrate temperature and Sb coverage. Both these surfaces have been observed with STM. Photoemission results for various coverages of Sb show that the surface-shifted components of the Ge 3d core level are suppressed by the deposition of Sb. A structural model, consistent with the data, for the (1 x 1) Sb-terminated surface is presented. Angle-resolved photoemission spectroscopy was used to measure the bulk band-dispersion relations along the high symmetry $Gamma$-$Sigma$-X directions for both Ge and Si.

This proceedings is based on the third Atomic Force Microscopy/Scanning Tunneling Microscopy symposium. The purpose of the meeting was to provide an interface between scientists, engineers, representatives of industry, government, and academia, all of whom have a common interest in probe microscopies. The papers have been written by experts in probe microscopy from around the world, representing a wide range of disciplines, including physics, biotechnology, nanotechnology, chemistry, and materials science.