Akiyoshi Matsuzaki

Control of structures of deposited polymer films by ablation laser wavelength: Polyacrylonitrile at 308, 248, and 193 nm

Extensive control of structures of deposited polymer films has been realized when the films have been prepared on a quartz or KBr substrate by laser ablation of polyacrylonitrile (PAN) with 308 (XeCl), 248 (KrF), and 193 nm (ArF) excimer laser beams, as revealed by scanning electron microscopy, infrared spectroscopy, x‐ray photoelectron spectroscopy, electron spin resonance, and x‐ray diffraction measurements. The original structure of PAN is essentially retained for the films deposited by ablation at 308 nm. Deformation and elimination of nitrile groups occur for the films prepared by ablation at 248 and 193 nm, respectively. Furthermore, a remarkable power‐dependent structural change has been observed at 248 nm; an increase in the laser power has led to ring closure of nitrile groups, resulting in the development of π‐conjugated systems. In addition, a rather high electric conductivity on the order of 10−2S cm−1 has been given to the films deposited by ablation at 248 and 193 nm on reirradiation with lo...

Preparation of amorphous organic semiconductor thin films with polyperinaphthalene structure on temperature-controlled substrates by excimer laser ablation of 3,4,9,10-perylenetetracarboxylic dianhydride

Abstract Amorphous semiconducting organic thin films are prepared on temperature-controlled substrates by excimer laser ablation (ELA) of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) with 308 nm (XeCl) beams. Drastic increase in electric conductivity and decrease in the FT-IR peak intensities related to the side groups of PTCDA monomers are observed for films prepared on substrates above 200°C. Electric conductivity of a film prepared on a substrate at 300°C comes up to 10−1 S cm−1. Raman spectroscopic measurement reveals that this film partially contains polyperinaphthalene (PPN) structure. Structural change by increasing substrate temperature and film formation process are discussed.

Preparation of polyacenic semiconductive thin films by excimer laser ablation

Abstract Polyacenic semiconductive thin films (PAS-TFs) were prepared onto a quartz or a KBr substrate by excimer laser ablation at 308 nm of a bulk phenol-formaldehyde (PF) resin and the bulk of a PAS material which was obtained by heat treatment of the PF resin at 535 °C (pyrolytic PAS (535 °C)). These were homogeneous brown and/or dark brown thin films consisting of fine particles. The electric conductivities of the films thus prepared from PF resin and pyrolytic PAS(535 °C) were about 10 −8 and 10 −5 S cm −1 at room temperature, respectively. Remarkable increase of electric conductivities was achieved on increasing the substrate temperature during the deposition process. In particular, the conductivity of the film from pyrolytic PAS (535 °C) reached more than 10 −2 S cm −1 , which is comparable to that of bulk PAS material prepared by pyrolytic treatment at 775 °C, when deposited on a substrate at 300 °C.

Improved Limb Atmospheric Spectrometer (ILAS)

Program overview, scientific targets and instrument design of the Improved Limb Atmospheric Spectrometer (ILAS) is described. The ILAS has two grating spectrometers for solar occultation measurement: one is for measurement of infrared band (850-1610 cm-1, 11.76 micrometers - 6.21 micrometers ) for O3, HNO3, NO2, N2O, H2O, CH4 and CFC11, and the other is for visible band (753-784 nm, O2 A band) for aerosols, temperature and air density measurement. ILAS will be onboard the ADEOS spacecraft and will observe high-latitude (N55-70, S63-87) ozone layer after February 1996 over 3 years with high vertical resolution (less than or equal to 2 km).

Preparation of polymer films by laser ablation of polyacrylonitrile: significant dependence on ablation wavelengths

Abstract Preparation of reorganized polymer films has been made by deposition of laser-ablated fragments of polyacrylonitrile (PAN), using XeCl (308 nm), KrF (248 nm), and ArF (193 nm) excimer lasers. Morphologies, chemical compositions and molecular structures of reorganized films were probed by scanning electron microscopy (SEM), IR spectroscopy and X-ray photoelectron spectroscopy (XPS). Significant dependence on ablation wavelengths was observed for structural variation as compared to the original PAN: the original structure was essentially preserved by ablation at 308 nm, while extensive cyclization of the nitrile group to yield condensed-ring formation was observed by ablation at 248 nm. Ablation at 193 nm caused elimination of the nitrile group.

Temperature and pressure retrievals from O2 A-band absorption measurements made by ILAS: retrieval algorithm and error analyses

A visible grating spectrometer of the Improved Limb Atmospheric Spectrometer (ILAS) aboard the Advanced Earth Observing Satellite (ADEOS) measured atmospheric absorption spectra at a wavelength region from 753 nm to 784 nm, including the molecular oxygen (O2) A-band centered at 762 nm, with a spectral resolution of 0.17 nm. Temperature and pressure profiles throughout the stratosphere were retrieved from the satellite solar occultation measurements of the O2 A-band absorption spectra. Based on simulation studies, root-sum-square errors associated with several systematic uncertainties in spectroscopic databases and instrument functions were estimated to be 4 K for temperature and 4% for pressure in the stratosphere. Current problems in this retrieval are also presented through comparisons with correlative temperature measurements.

Preparation of polythiophene thin films by UV laser-assisted deposition of 2,5-dichlorothiophene with a 248 nm excimer laser beam

Abstract Polythiophene thin films are prepared by UV laser-assisted deposition (UV-LAD) of 2,5-dichlorothiophene (2,5-DCT) with a 248 nm (KrF) beam at several fluence values. Surface morphologies of the films dependent strongly on laser fluence and deposition rate of the reactant. In the optimized conditions, mesh-like structures consisting of numerous fibers were observed. Electric conductivity of the film prepared by UV-LAD at 10 mJ cm−2 pulse−1 increased from less than 10−7 S cm−1 up to 10−3 S cm−1 on iodine doping. FT-IR, photoelectron spectroscopy (XPS) and ultra violet—visible (UV—vis) spectroscopy measurements show that, although sulfur atoms are eliminated to some extent, polymerization occurs basically at 2 and 5 positions of 2,5-DCT by effective elimination of halogen atoms to form polythiophene with various π-conjugation lengths. The film contained both soluble and insoluble components in tetrahydrofuran (THF) and acetonitrile (AN) solvents. Components with π-conjugation length corresponding to those of an oligothiophene with 3 ± 1 thiophene units are dominant for soluble components. Optical band gap is estimated to be 2.93 eV for insoluble components in the film.

Preparation of low-dimensional conducting polymer films by UV light-induced deposition with excimer laser beams

Abstract Studies on preparation of low-dimensional conducting polymer films by two kinds of UV light-induceddeposition methods with excimer laser beams are presented. Polythiophene thin films are prepared from several thiophene derivatives by exoimer laser chemical vapor deposition (ELCVD) with 193nm (ArF), 248mn (KrF) and 308nm (XeCl) beams. A film with highly oriented fibrous structure is obtained from 2,5-dichlorothiophene (2,5-DCT) by ELCVD with a 193nm beam. Excimer laser ablation (ELA) of 3,4,9,10-perylenetetracarboxylicdianhydride(PTCDA) with a 308nm (XeCl) beam results in formation of semiconductive organic thin films consisting of polyperinaphthalene (PPN) structure on a substrate at 300 °C.

Optimized structures of Cr2(CO)6+ with three different symmetries by density functional calculation

Density functional calculations have been made on a binuclear metal carbonyl ion Cr2(CO)6+ found in our laser ablation–molecular beam (LAMB) experiment. Optimized structures are calculated for three different conformations: T33 of D3d symmetry with three terminal carbonyl groups on each chromium atom, B2T22 of D2h symmetry with two bridging carbonyl groups and two terminal carbonyl groups on each chromium atom, and B4T11 of D4h symmetry with four bridging carbonyl groups and one terminal carbonyl group on each chromium atom. The most stable conformation is T33 which is 36.76 and 286.44 kJ mol−1 lower in energy than B2T22 and B4T11, respectively. The difference of conformation exerts a significant influence on the internuclear distance between chromium and the carbon of terminal CO, but hardly on the Cr–Cr bond length. For B2T22 and B4T11, longer C–O distances for bridging carbonyls compared with those for terminal ones indicate effective π*-back donation from the chromium atom to the bridging carbonyl groups. Furthermore, the relative abundance of Cr2(CO)n+ (n = 0–6) observed in our previous experimental study can be explained qualitatively by comparison of the excess energy produced in the formation of a Cr+–Cr bond with the CO dissociation energy of Cr2(CO)6+.

Improved limb atmospheric spectrometer and retroreflector in-space for ADEOS

The ILAS and RIS instruments for Advanced Earth Observing Satellite intended to perform laser absorption measurements are described. The ILAS measurements will provide vertical profiles of ozone and ozone-related species in the polar regions. The RIS will obtain vertical profiles of ozone, carbon dioxide and methane as well as column density of some greenhouse gases based on laser absorption measurements.