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The magnetic properties and microstructures of granular Co/sub 60-X/Pt/sub X/C/sub 40/ (0/spl les/x/spl les/23) thin films, fabricated by ion-beam sputtering and subsequent annealing, were investigated. High coercivity was obtained in samples with Pt concentrations ranging from 12 to 16 atomic percent, with a maximum coercivity of 1800 oersteds. These films consisted of CoPt grains having a CoPt disordered alloy phase, which were separated by a C phase. The magnetic grains had an average size of 10 nm and a faulted hexagonal close-packed structure. Below 16 at.% Pt content, the improvement in coercivity with Pt was most likely related to an increase in the magnetocrystalline anisotropy of the CoPt alloy compared to that of the Co. Above 16 at.% Pt content, a drastic decrease in coercivity was observed. It is found that for these large Pt concentrations a higher annealing temperature is required to improve the coercivity with Pt addition.

Oxomolybdenum phthalocyanine (MoOPc) and tin phthalocyanine (SnPc), which both have a pyramidal molecular shape, were deposited onto sapphire by organic molecular beam deposition. The crystalline phase of these films was determined to be triclinic by X-ray diffraction and absorption spectra with reference to previously formed titanylphthalocyanine (TiOPc) and vanadylphthalocyanine (VOPc) films. Values for the third-order nonlinear optical susceptibility χ(3) of the triclinic MoOPc and SnPc films were slightly smaller than those of TiOPc and VOPc but still much larger than those of planar metallophthalocyanines such as copper phthalocyanine and zinc phthalocyanine. Molecular shape is an important factor determining the nonlinear optical properties of metallophthalocyanines.

Fine droplets of nematic liquid crystal (LC) with a diameter less than 100 nm were obtained in ultraviolet curing polymers. The transparency of the material was kept high in the infrared regions because there was little scattering in comparison to materials containing much larger droplets. The fine droplets were found to respond to an electric field, causing a change in birefringence. This change was about 0.0004 at the applied voltage of 5.5 V/μm. The special features of low transmission loss and easy film formation will enable one to apply LCs to optical devices of the wave guide type.

A VARIETY of crystalline materials have now been encapsulated in nanometre-scale graphitic cages1–8 and tubules9–11. For magnetic materials, encapsulation should serve the dual role of protecting air-sensitive particles against degradation and reducing the magnetic coupling between individual particles, thus potentially opening the way for applications of these composite materials as ultra-high-density magnetic recording media12,13. But to realize this potential, the materials must be available in the form of thin, smooth films, with precise control of the size of the individual magnetic crystallites. Here we report the fabrication and characterization of magnetic thin films, consisting of cobalt nanocrystals encapsulated in graphite-like carbon cages, that meet these structural requirements.

The initial domain structure of hydride vapor phase epitaxy grown GaAs films on Si(001) was investigated using x‐ray standing waves. GaAs/Si(001) samples, 4 monolayers (ML) thick, grown on two different Si substrates were used: an epitaxial Si surface and a mechanochemically polished surface. X‐ray standing‐wave analysis revealed no single‐domain structure in either sample. The ratio of the two domains was almost 1:1 on the mechanochemically polished surface and 6:4 on the epitaxial Si surface. The dominant GaAs domain on the epitaxial surface was the same as that obtained on thicker GaAs films on an epitaxial Si surface. This suggests a rapid decrease in the GaAs domain during the early stages of growth on an epitaxial Si surface.

The LET distributions in front of the 80 cm-thick concrete side shield at the CERF facility were measured with a Si detector telescope (RRMD-III) covered with and without a 1 cm-thick acrylic plate. In these measurements, a slight difference between the LET distributions was seen as a result of recoil protons and/or carbon particles by neutrons. Also, the LET distributions are compared with the micro-dosimetric spectrum (i.e., lineal energy distribution) measured with a cylindrical TEPC under the same conditions.

Self-organizing properties of materials can be used to fabricate well-ordered nano- structures on a large scale and also to develop new advanced materials. Three examples of self- organized nano-structures are described in this paper. A unidirectionally ordered metallo phthalocyanine thin film was formed over the entire surface of a sapphire (1102) substrate by using a newly synthesized dibenzo[ b,t] phthalocyaninato-Zn(II), which has a unique two-fold symmetrical molecular structure. A buried SiO2 layer with atomically abrupt Si/SiO2 interface was formed by oxygen ion implantation into silicon and subsequent annealing. A nano-particle consisting of outer graphitic shells and a core nano-crystal of LaC2 was formed in a self-organizing manner when a hot carbon-langhanum particle was cooled on an arc-discharge electrode in a He atmosphere.

In 1997, four dosimeter packages, each of which contains two CR-39 plates and 18 TLDs (Mg 2 SiO 4 :Tb), were placed inside the MIR Space Station and flew on an orbit with an inclination angle of 51.6° and an altitude of approximately 400 km for 40 days. We estimated the absorbed doses, dose equivalents and effective quality factors during the flight by combining CR-39 data and TLD data. We then compared these results to those obtained with the same analysis method from the dosimeter packages on board Space Shuttle missions STS-79, -84 and -91 that flew along the same orbit. Finally, the differences between our results and those obtained by another group using passive dosimeters on the MIR are discussed.

Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared.

The LET distributions during the Space Shuttle missions STS-84 (altitude 270– 412 km , average 375 km ; inclination angle, 51.6°) and STS-91 (altitude 328– 397 km , average 373 km ; inclination angle, 51.6°) were measured using CR-39 plastic nuclear track detectors. A correction for the dip-angle dependence of the track-formation sensitivity of the CR-39 plates was applied to the data analysis. The absorbed doses and the dose equivalents around RRMD Detector Units, estimated from the LET distributions in the LET region of 4– 200 keV / μm , fluctuated with standard deviations of ±21% to ±35% in both flight experiments. The LET distributions obtained from the CR-39 plates agreed well with that obtained from RRMD-II in STS-91. However, the particle fluxes obtained from RRMD-III in STS-84 and STS-91 were two or three times higher than those obtained from RRMD-II and the CR-39 plates. It was concluded that the LET distributions obtained from RRMD-II and the CR-39 plates in the present flight experiments did not include the contribution of target-fragmented secondary heavy particles produced by low-LET particles, such as relativistic or semi-relativistic protons and helium ions, whereas RRMD-III was able to detect these secondary particles because of its low triggering level.

Epitaxial C60 films grown by molecular beam deposition onto CaF2(111) surfaces are investigated by reflection high‐energy electron diffraction at deposition temperatures of 30–300 °C and coverages corresponding to average thicknesses of 1–50 nm. Over this entire temperature range, C60 forms an incommensurate overgrowth of stacked hexagonal layers exhibiting a characteristic nearest‐neighbor spacing of 0.98 nm. Below 170 °C, unidirectional growth occurs in accordance with the crystallographic directions of the substrate. At higher deposition temperatures, however, two equivalent, rotated domain orientations are observed which are characterized by a significantly lower degree of lattice mismatch.

We used organic molecular beam deposition (OMBD) to deposit vanadylphthalocyanine (VOPc) and titanylphthalocyanine (TiOPc) on sapphire R(1102) surfaces. The Q band absorption peaks of these films shift to longer wavelengths when deposition temperatures are higher. The spectra are grouped by the peak position, which is characteristic of the phase of the film and consistent with X-ray diffraction results. We could observe the spectra of amorphous, phase II, and another unknown high-temperature phase of VOPc and TiOPc separately

Space radiation dosimetry measurements have been made onboard the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2: 28.5 degrees x 300 km: 14.68 days) and the STS-79 in the 4th Shuttle MIR mission (S/MM#4: 51.6 degrees x 300-400km: 10.2 days). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD-I for IML-2 and RRMD-II with improved triggering system for S/MM#4)" utilizing silicon semi-conductor detectors and the other detectors are conventional passive detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. The main contribution to dose equivalent for particles with LET5.0 keV/micrometer (IML-2) and LET3.5 keV/micrometer (S/MM#4) is seen to be due to galactic cosmic rays (GCRs) and the contribution of the South Atlantic Anomaly (SAA) is less than 5% (IML-2: 28.5 degrees x 300 km) and 15% (S/MM#4: 51.6 degrees x 400 km) in the above RRMD LET detection conditions. For the whole LET range (0.2 kev/micrometer) obtained by TLDs and CR-39 in these two typical orbits (a small inclination x low altitude and a large inclination x high altitude), absorbed dose rates range from 94 to 114 microGy/day, dose equivalent rates from 186 to 207 microSv/day and average quality factors from 1.82 to 2.00 depending on the locations and directions of detectors inside the Spacelab at the highly protected IML-2 orbit (28.5 degrees x 300 km), and also, absorbed dose rates range from 290 to 367 microGy/day, dose equivalent rates from 582 to 651 microSv/day and average quality factors from 1.78 to 2.01 depending on the dosimeter packages around the RRMD-II "Detector Unit" at the S/MM#4 orbit (5l.6 degrees x 400km). In general, it is seen that absorbed doses depend on the orbit altitude (SAA trapped particles contribution dominant) and dose equivalents on the orbit inclination (GCR contribution dominant). The LET distributions obtained by two different types of active and passive detectors, RRMDs and CR-39, are in good agreement for LET of 15 - 200 kev/micrometer and difference of these distributions in the regions of LET15 kev/micrometer and LET200 kev/micrometer can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks and chemical etching conditions.

C70 grown on a NaCl substrate is observed by transmission electron microscopy (TEM) at low temperature (104 K). New spots that appear reproducibly in the electron diffraction (ED) at low temperature can be indexed as (m±1/2, n±1/2, 0) (m, n: integer) in a [001]hcp projection. The lattice constant a is lower at low temperature and the reduction ratio is a104 K/a300 K=1.02/1.06 nm=0.96±0.02, which is much lower than the value reported for C60. The ED of the low‐temperature phase is observed below about 260 K, and an intermediate state is also detected in this temperature range.

A high-performance EUV/soft X-ray ellipsometry system using multilayer mirrors has been developed. A couple of multilayer mirrors were used for the polarizer, and two multilayer mirrors were used for the rotating analyser. The multilayer mirrors were optimized to obtain a medium extinction of about 2000. An extinction ratio of the polarizer up to 104 can be achieved by using two multilayer mirrors, and the calculated reflectivity was more than 35%. The calculated error of the optical elements reveals that the error of the polarizer and misalignment optical parts is mainly of the first order, and that of the analyser is of the second order.

Granular thin films consisting of cobalt nanocrystals encapsulated in graphite-like carbon were fabricated by co-deposition of cobalt and carbon with subsequent annealing. The gram size and the crystal structure of the Co-C films depended on the substrate temperature, the carbon concentration, and the annealing temperature. The film deposited with 36 at.% carbon at 200°C consisted of crystalline carbide and hep cobalt, which transformed into hep cobalt and graphite-like carbon by annealing at ≥300 °C. The as-deposited film with a carbon of 46 at.% had an amorphous-like phase and grain sizes of ≤10 nm. By annealing at ≥300°, the amorphous-like phase transformed into cobalt grains with a random stacking structure encapsulated in graphite-like carbon, and the initial size of the grains was unchanged. The saturation magnetization and the in-plane coercivity of these films were also reported.

Droplets of liquid crystal (LC) have been energetically investigated during the last ten years.(1) Most of the research has aimed at making use of scattering(2) and diffraction,(3) which occurs either at the surface of individual droplets or at the surface of a layer consisting of many droplets. The droplets were mostly micro-sized. Our aim, however, is to make use of nano-sized LC droplets for active optical devices such as optical switches or tunable filters. The surfaces of nano-sized LC droplets are too small to scatter light, so the total intensity of transmitted light is not changed, but the phase or polarization can be controlled by the birefringence generated by the response of nano-sized LC droplets to an electric field shown in Figure 1. There have been only a few works(4) including ours,5) which have similar aims. We have already reported the preparation of droplets about 50 nm in diameter and shown they respond to an electric field. In this work, we prepared the polymers containing nano-sized LC droplets by various conditions and measured their electro-optic effect, propagation loss, and response time.

In a transmission electron microscope, we have shown that an amorphous boron filament can be obtained by Vapor-Liquid-Solid growth under intense electron irradiation (current density > 100 A/cm2) on an amorphous Boron Nitride film deposited a few-nm gold as agent. The grown filaments have gold particles on the tops and the diameter were from 10 to 100 nm. Detailed analysis of Electron Energy-Loss Spectrum of the amorphous boron was carried out. We also dynamically observed shrinking of filaments by evaporation of boron through gold particles. As a special case, boron-rich tubules of several hundreds nm diameters were also formed.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An example of structural control of organic thin films by self-organization is described. Equally spaced parallel atomic step arrays exist on polished sapphire (1012) surface. Dibenzo [b, t] phthalocyaninato-Zn (II) (ZnDBPc) molecules deposited by UHV molecular- beam deposition on this surface stack themselves to form columnar crystal grains. Since the direction of these columns is parallel to the atomic step direction, thin films of ZnDBPc grown on the sapphire (1012) surfaces show unidirectional in-plane ordering over the entire substrate. The direction and spacing of the parallel atomic step arrays are directly related to the misorientation direction and angle of the polished surface from the exact (1012) surface. Therefore the ordering direction of the ZnDBPc thin film has no relation to the crystallographic axes of the sapphire, which is totally unlike ordinary epitaxial growth. Since the step spacings can be controlled over a wide range, we can expect to be able to improve the ordering by adjusting the step spacings to the lattice spacing of organic crystals.

Nano-sized fine droplets of liquid crystal (LC) were obtained by phase separation of nematic LC in UV curing polymer. The polymer composite had a high transparency in the infrared region. The fine droplets responded to an electric field causing a change in birefringence. Output power change was brought about by the generated retardation between two polarizations, parallel and perpendicular to the applied electric field. This differs from the composite containing much larger droplets, where output depends on the degree of scattering. The birefringence changed by 0.001 at the applied voltage of 7.5 V/μm.

Electron and x-ray-diffraction studies of nanotubes have revealed that the distances between the graphitic sheets are larger by a few percent than those in bulk graphite. The mean value of the interlayer spacings is 0.344\ifmmode\pm\else\textpm\fi{}0.001 nm.

The distributions of linear energy transfer for LET (LETwater) in front of the 80-cm-thick concrete side shield at the CERN-EU high-energy reference field (CERF) facility were measured with a Si detector telescope named real-time radiation monitoring device-III (RRMD-III) covered with and without a 1 cm-thick acrylic plate. In these measurements, a difference of about 20% in the absorbed dose between the two LETwater distributions was observed as a result of protons, deuterons and tritons recoiled by neutrons. The LETwater distribution obtained using RRMD-III without the 1-cm-thick acrylic plate is compared with lineal energy distributions obtained using the dosimetric telescope (DOSTEL) detector under the same conditions. These dose equivalents are also compared with that obtained using HANDI TEPC which is used as the standard at the CERF facility.

The X-ray emission spectra of crystalline carbon nitride films deposited by electron-cyclotron-resonance (ECR) plasma sputtering were observed using a high-resolution soft X-ray spectrometer at the Advanced Light Source to investigate the electronic structure of carbon nitride crystals. The spectral features in C K and N K X-ray emissions from the ECR-deposited carbon nitride films represent the highly degenerated valence orbitals and their highly pure crystalline form. The C K and N K X-ray emission spectra were approximately explained based on the C2p and N2p density of states in the hybridized C–N bonds. The absence of significant peak shifting in selectively excited C K and N K X-ray emission spectra showed that there is a fairly nondispersive structure between valence and conduction bands in ECR-deposited carbon nitride films.

A new telescope consisting of three two-dimensional position-sensitive silicon detectors which can measure the linear energy transfer (LET) distribution over the range from 0.2 to 400 keV/µ m has been developed as a real-time radiation monitor in manned spacecraft. First, the principle of LET measurement and its design method are described. Second, suitable electronic parameters for the LET measurement are experimentally determined. Finally, the telescope performance is investigated by using relativistic heavy ions. The first in-flight test of this type of telescope on the US Space Shuttle (STS-84) is scheduled for May, 1997.

Thin films of dibenzo [b, t] phthalocyaninato-Zn(II) (ZnDBPc) were grown by UHV molecular beam deposition on polished sapphire (1̄012) surfaces. The structural and optical properties of the ZnDBPc films were investigated by atomic force microscopy, X-ray diffraction, polarization spectroscopy, and optical third harmonic generation. The films showed in-plane ordering over the entire substrate. Equally spaced atomic step arrays were clearly observed on the polished sapphire (1̄012) surface. The ZnDBPc molecules stacked themselves to form molecular columns, and the stacking direction was parallel to the step direction, resulting in in-plane ordering of the ZnDBPc films. The ordered ZnDBPc film strongly promoted the ordering of a TiOPc thin film deposited on it. The third-order nonlinear optical susceptibility χ(3) of this ordered TiOPc/ZnDBPc double-layer film showed high anisotropy, and its maximum χ(3) value was 3.0×10-10 esu.

X-ray standing waves were used to characterize the density and the interface roughness of multilayers. To include the interface roughness effect into consideration, the X-ray wave amplitude in the multilayers was described in terms of a modified optical matrix. Simulation results show the possibility of determining both roughness and density of multilayers, independently. Analysis of a Ni/C multilayer with a period of about 54.6 Å showed the interface roughness was 10 Å and the density of the nickel layer was equal to the bulk value. The uniqueness of the roughness and the density was confirmed by calculating standing wave profiles for various roughnesses and nickel layer densities.

Electron energy loss spectroscopy has been used to investigate the B- K spectra of individual filaments grown by electron beam irradiation. We also measured the energy loss spectra of β-rhombohedral boron and B4C for reference. High-resolution transmission electron microscope images, micro-electron diffraction patterns, and elemental analysis by energy loss spectra revealed that the filaments consist of amorphous boron. The similarity of B- K near-edge structures between the filaments and the reference forms of boron suggests that the filaments have B12 icosahedra as their basic structural unit, which is consistent with previous structural studies of amorphous boron. The different peak sharpnesses just above the B- K edge may reflect differences in structural complication and/or disorder of B12 icosahedron units.

Titanylphthalocyanine is deposited onto sapphire by organic molecular beam deposition to grow films of 2.5 to 100 nm. The first layer grown on the sapphire surface is not phase II; however, phase II grows on the first layer. The first layer is annealed and changed to phase II during deposition. The Q-band of phase II shows a large redshift. Calculations using molecular exciton theory show that molecular columns grow in two directions parallel to the substrate surface. Each of these columns has a favorable molecular arrangement for a large redshift, such as J-aggregates. The film thickness has a low dependence on the redshift, a result which is consistent with the calculation results.

A method of determination of charge and energy for energetic particles penetrating (not stopping) a multilayer silicon Δ E×E telescope with a finite thickness (12 mm) is examined in the energy region up to several hundreds of MeV/nucleon. From the results of the accelerator experiment, an energy resolution σ E of 1.2% in rms and a charge resolution σ Z of 0.11 charge unit in rms for Fe-group nuclei with energies between 190 and 230 MeV/nucleon are obtained. For lighter elements such as hydrogens and helium ions, an energy resolution σ E of 2.9% is obtained in the energy region between 33 and 42 MeV/nucleon and even their individual isotopes are separated. Also, the energy dependences of these resolutions suggest that this method can be utilized for particles with energies about two times larger than that corresponding to the range of telescope thickness for the evaluation of the space radiation effects even under the limitations of weight, size, and electric power supply.

We describe highly ordered thin films of metallophthalocyanine (MPc) formed by an organic molecular beam deposition technique using a novel less-symmetrical MPc derivative, 2,3:12,13-dibenzophthalocyaninato-Zn(II). Ordered structure is confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) as well as by polarization spectroscopy. At a substrate temperature of about 200°C, strip-shaped crystals with sub-micron grain sizes are aligned in one direction over the whole 10×13-mm surface of the sapphire (11̄02) substrate. The dichroic ratio at the Q-band peak is more than 5 for as-deposited films.

Arc discharging carbon rods containing 8.8 wt% La2O3 produces a carbonaceous deposit containing nano-particles (nm-size particles) consisting of graphite shells around core nano-crystals averaging 10-30 nm in diameter but sometimes 3-4 nm. Transmission electron microscopy, nm-size electron diffraction and electron energy-loss spectroscopy have revealed that the nano-crystals are La-carbide, LaC2, that the interfaces between the carbide and the graphite are flat, and that no intermediate layers are formed.

Extremely fine particles of iron were prepared by vacuum evaporation onto a running oil substrate. Particles thus prepared were suspended in the oil and their average diameter was about 25 A. From the electron diffraction analysis, it is found that the main constituent of the suspended particles is Fe3O4. Magnetic measurements revealed that these particles showed superparamagnetism whose blocking temperature was distributed between 10 and 30 K, and that the magnetic interaction among these particles was negligibly small.

In order to investigate its mass resolution, a stack of sheets of the plastic CR-39 was exposed to a beam of 600 MeV n 56 Fe ions. From this exposure, a total of 74 iron events were analyzed. The mass resolution for 56 Fe was obtained as 0.34 ± 0.14 amu.

A “pure” liquid argon calorimeter has been constructed with the aim of approaching the ideal high energy resolution. The electrode system of the calorimeter consists of 192 G-10 plates of 1.2 mm thickness placed at intervals of 9mm. The sensitive volume of the calorimeter is 0.93 m2 × 2.0 m. An energy resolution of (2.4±0.2)% (m.m.s.) was achieved of these formulas is discussed. compared to the values predicted by Waseda's and Serpukhov's formulas. The validity of these formulas is discussed.

Fine metal crystallites with diameters 200~2000 A made by evaporating a metal in an atmosphere of an inactive gas were studied by electron microscopy. It is found that the crystal habit common to Be, Cr, Mn and Fe, which are bcc just below the melting point, is rhombic dodecahedra truncated by {100}. Fcc metals show six different types of crystal habit. However,only one, viz. octahedra truncated by {100}, is a single crystal and all the others have twins. Various degrees of truncation were found both for rhombic dodecahedra and octahedra. Crystallites with certain degrees of truncation are possibly Wulff polyhedra.

To measure the flux ratio of ultraheavy cosmic ray particles (UH) with Z >45 and cosmic ray Fe nuclei at a mean geomagnetic cut-off rigidity of 10 GV, detector arrays were exposed for a net total of 45.2 m 2 ·days in two balloon flights in 1976 and 1982. The fluxes of particles with Z >45 and Fe nuclei at the top of the atmosphere are presented. From comparison between the [UH]/[Fe] ratio of these experiments and that of the others at low rigidity region, it is shown that the energy spectrum of UH is somewhat different from that of Fe in the energy range between 1–10 GeV/amu. Propagation calculations have been made to examine energy spectra of various cosmic ray particles. The results of the calculations show that the difference in the energy spectrum can be explained mainly by the energy dependent nuclear fragmentation process during the propagation of cosmic ray particles.

A new CR-39 plastic containing a small amount of antioxidants (Naugard-445) has been developed for use in a search for massive magnetic monopoles. Its characteristics have been investigated from the standpoint of the “heavy etching method”, which was proposed several years ago. The results are compared with those of pure CR-39 plastics measured under the same conditions.

A stack of the plastic CR-39 and nuclear emulsions was exposed at a vertical cut-off rigidity of 10.3 GV and an atmospheric depth of 7 g/cm2 for 30 h in May, 1979. Characteristics of shapes of etched cones produced by relativistic cosmic ray heavy nuclei in CR-39 are investigated and it is found that the surface ellipse of the etched track with large dip angle becomes more deformed. The detection threshold value is obtained to be Z/β ≅ 6 and the charge resolution (root mean square) to be ΔZ ≅ 0.4 charge units for relativistic iron nuclei in CR-39.