Natsu Uyeda

The metal-ligand vibrations in the infrared spectra of various metal phthalocyanines

Abstract The infrared spectra of phthalocyanine and seven divalent metal derivatives have been recorded in the region 400–4000 cm−1. The metal-ligand vibration and other metal dependent bands were found and the anomalies of Cu2+ and Zn2+-phthalocyanines were interpreted on the basis of electronic configurations of outer orbitals of the metals.

Molecular image resolution in electron microscopy

In order to determine the ultimate molecular resolution attainable with a conventional electron microscope, the direct observation of hexadecachloro‐Cu‐phthalocyanine molecules was attempted. Since phthalocyanine derivatives are known to form crystalline films with columns of parallel stacks of planar molecules, the specimens were prepared by epitaxial growth on KCl cleavage face through vacuum evaporation so that the column axis was directed almost normal to the thin‐film surface holding an orientation suitable for the observation. The molecular orientation was determined by Patterson synthesis based on the laser optical transform of the electron diffraction pattern obtained from the individual crystallites placed on the microgrid mesh. The direct observation was carried out with the 100‐kV electron beam incident on the specimen along the column axis. The crosslike images arrayed in a centered rectangular net were clearly resolved, well representing the molecular shape of phthalocyanine with the configur...

Orientation Overgrowth of Condensed Polycyclic Aromatic Compounds Vacuum‐Evaporated onto Cleaved Face of Mica

When Pt‐, Cu‐, and Zn‐phthalocyanines are vacuum‐evaporated onto cleavage faces of muscovite, single‐directional orientation occurs at lower substrate temperature. At higher temperature ranges, Zn‐phthalocyanine has a double‐directional orientation while Pt‐ and Cu‐phthalocyanines show triple‐directional ones. High‐resolution electron diffraction patterns, which were well‐defined fiber diagrams, revealed that all three compounds showed conspicuous isomorphism with one another, and Zn‐ and Cu‐phthalocyanines occurred in the metastable forms of their dimorphs. General crystal structures of metastable forms are discussed on the basis of the found isomorphism with Pt‐derivative.Evaporated films were composed of lamellar crystal strips, and the fiber diagrams showed that at least two kinds of lattice orientations were assumed by all three compounds, while the longitudinal crystal axis of individual strips always ran parallel to their b axes.As to relative orientation of the evaporated films to the substrate, t...

A new method for optimal-resolution electron microscopy of radiation-sensitive specimens

A new technique as well as a practical device, Minimum Dose System (MDS), have been developed for taking a high resolution image of radiation-sensitive specimens, on the basis of the principle of minimum beam method. Images of Ag—TCNQ and Zn—phthalocyanine crystals are photographed at atomic and molecular resolutions with 200 and 100 kV electron microscopes both equipped with MDS. Here, the total end-point doses are 0.3 and 1 C/cm 2 , respectively. The possibility is indicated that PTA might alter the native structures of biological specimens through its crystal formation. This system is also capable of taking through-focus high resolution photographs of radiation-sensitive specimens.

Nucleus interaction and fine structures of colloidal gold particles

Abstract Typical gold sol particles were examined by high-resolution electron microscopy to study the nucleation and growth mechanism. The samples of colloidal gold were Faraday sol, Weimarn sol and sodium citrate sol, whose average particle diameters were estimated to be 55.2 ± 10.6 A, 131 ± 13 A and 154 ± 70 A, respectively. The shape of particles is mostly spherical excepting some of the Weimarn sol which includes pentagons with some round apices. The high resolution electron micrographs taken at a magnification of 125,000 times clearly show that the majority of the particles consist of smaller elementary crystallites with sharp boundaries which appear as parallel or radial lines defined by distinct diffraction contrasts. Moire fringes of 5–8 A spacings as well as crossed lattice images of 2.03 and 2.35 A due to (200) and (111) reflections were also observed. Systematic analyses of these contrasts indicated that the particles are formed by parallel or radial twins with definite mutual orientations. The origin of the fine structure can be attibuted to the nucleus interactions which precedes the actual growth in the early stage of sol formation. The possibility of the formation of metastable nuclei with icosahedral configuration which grow into the multiple twins and the successive transition to the natural cube-octahedral nuclei which after mutual interactions lead to the parallel twins was also discussed.

Improved high resolution image processing of bright field electron micrographs: II. Experiment

Abstract The new methods of nonlinear image processing are applied to high resolution experimental micrographs of chlorinated copper phthalocyanine taken on the Kyoto 500 kV electron microscope. With these new methods of image processing the phase and amplitude of the specimen transmission function are reconstructed from a defocus series of conventional transmission electron micrographs (bright field). Strong scattering, partial coherence and statistical noise have been included. Both of these new methods are based on the MAP (maximum a posteriori) criterion generalized to include reconstruction from multiple input images. In a companion paper (the first part of this two-part report) the theory behind these methods was presented and in this paper it is tested on actual experimental micrographs. A significant increase in resolution has been obtained with computer image processing. The point-to-point resolution obtained here with computer image processing of 500 kV electron micrographs is of the order of 1.2–1.4 A which represents a 30–50% increase in resolution.

High-resolution TEM images of zinc phthalocyanine polymorphs in thin films

The structure of a vacuum-deposited polycrystalline film of zinc phthalocyanine, C32H16NsZn, has been investigated by high-resolution electron microscopy. With the aid of a minimum-dose system, the molecular arrangements in crystals were observed and the existence of at least three polymorphs were confirmed in the film.

Thermal transformation of vacuum-condensed thin films of copper-phthalocyanine

Abstract Copper-phthalocyanine forms thin crystalline films of the metastable α-form with definite epitaxial orientations when vacuum- deposited onto a cleaved face of muscovite. The thermal transformation of these thin films into the stable β-form was observed by electron microscopy and electron diffraction. The transformed crystals show an epitaxial orientation with their (001) faces parallel to the substrate independent of the initial orientations. The β-form crystals grow as a long needle along its b -axis when it coincides with that of the original α-crystals, while the β-form crystals appear as relatively short flakes when both b -axes show no coincidences at all. The mechanism of thermal growth is discussed on the basis of molecular arrangement from one crystal to another as well as the influence of the lattice structure of the substrate surface.

Surface pressure dependence of monolayer structure of poly-ϵ-benzyloxycarbonyl-l-lysine

The surface pressure dependence of the monolayer structure of PBCL was studied by means of infrared spectroscopy and electron microscopy, and discussed in connection with the characteristic feature of the π-A isotherm. The main conclusion is as follows. The PBCL molecules are in the α-helical conformation in the monolayer on the water surface and helix axes lie flat on the surface as condensed ordered arrays forming a certain angle with the compressing direction. The series of transitions observed in the π-A isotherm is ascribed to the consecutive formation of additional layers of molecules. During these processes, the molecular conformation is left unchanged. This conclusion is consistent with Malcolms proposal on PBCL (11, 12).

The observation of molecular orientations in crystal defects and the growth mechanism of thin phthalocyanine films

The crystal imperfections in very thin films of metal-phthalocyanines were observed by means of high-resolution electron microscopy. It was revealed that the anisotropic molecular shape played an important role in the formation of the defect and grain boundaries. The quasi-amorphous state of phthalocyanine was found in which the existence of a linear crystal, a molecular column, was confirmed in the early stages of the formation of the three-dimensional crystal.