摘要:

Soft x-ray spectral radiations from Xe,H2O,andCO2cryogenic targets irradiated by a 1 &mgr;m neodymium doped YAG-slab laser at pulse widths of 12–20 ns and at laser intensities of5×1010–1012 W/cm2have been observed. These targets radiate soft x-rays in a wavelength range of 10–13 nm which is useful for projection microlithography. We have found a strong x-ray spectral peak at&lgr;=10.8 nmwith a Xe cryogenic target. The measured x-ray conversion efficiency with the Xe target was0.8&percent;/sr(&lgr;=10.8±0.27 nm)at a laser intensity of1×1012 W/cm2.This was ten times or more efficient than that withH2OandCO2targets. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120708

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The effect of ambient gas on the dynamics of the plasma generated by laser ablation of a carbon target using 1.06 &mgr;m radiation from a Q-switched Nd:YAG laser has been investigated using a spectroscopic technique. The emission characteristics of the carbon plasma produced in argon, helium and air atmospheres are found to depend strongly on the nature and pressure of the surrounding gas. It has been observed that hotter and denser plasmas are formed in an argon atmosphere rather than in helium or air as an ambient. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120602

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A process is described whereby hcp rare-earth metals can be grown heteroepitaxially as high-quality single-crystal films with thebaxis normal to the growth plane. The growth employs molecular beam epitaxy, starting from available sapphire substrates. The results of characterization by several techniques are described. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120675

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Nanoparticle chain aggregates (NCA) possess elastomeric properties including stretch under tension, and contraction when the tension is relaxed. Individual chain aggregates of 7 nm titania particles a few hundred nm long were observed in the electron microscope. The NCA were stretched across expanding holes in the carbon film on an electron micrograph grid. After stretching up to 90&percent;, the NCA broke loose at one end and contracted to a tightly folded chain. This pattern was observed in repeated tests. Mechanisms for this behavior and reasons for its generality are proposed. Implications are discussed for the ductility of nanoparticle ceramics, and the increased tensile strength and elastic modulus of rubber due to nanoparticle additives. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120676

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Chemically passivated gold nanoclusters deposited on the surface of graphite have been manipulated with the scanning tunneling microscope (STM) in ultrahigh vacuum. The controlled clearing of a definite shape in a cluster layer is demonstrated. Clusters embedded in a close-packed array could not be removed from the surface, apparently because of the attractive interaction between neighboring ligand chains. A minority channel of cluster fragmentation has been identified and leads to the creation of platelets which can be further manipulated by the STM tip. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120677

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We investigated the composition-dependent size of pseudomorphicSi1−xGexislands on Si(001).Si1−xGexlayers with0.05⩽x⩽0.54were deposited from metallic solution. The island growth occurs near thermodynamic equilibrium and facilitates a comparison of the results with predictions based on energetics. We find pseudomorphic islands with base widths ranging from several&mgr;m to a few nm. We show that it is possible to adjust the island size by simply choosing the appropriate layer composition. Varying deposition temperatures and growth velocities do not affect the scaling behavior. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120622

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Neutron and high-resolution synchrotron x-ray diffraction measurements have indicated a tetragonal zirconia phase with both an axial ratio of unity and internal shear deformation: The oxygen displacements from ideal fluorite positions of 0.088 and 0.078 Å are observed for 65 and 70 mol &percent;CeO2–ZrO2samples, respectively, although bothc/avalues are 1.000±0.001. Thec/aratio decreases with increasing ofCeO2content and decreases discontinuously to unity around a 60 mol &percent;CeO2composition, while the oxygen displacement decreases continuously up to about 90 mol &percent;CeO2.©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120678

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We present a comparative study of two-dimensional electron gas structures, which were grown on(511)AGaAs substrates and on conventional (100) GaAs substrates. The study included both normal interface and inverted interface structures. The(511)Apresents consistently and substantially improved transport properties, whose origin can be traced to the growth dynamics of these surfaces. We conclude that(511)AGaAs promises to serve as an alternative and superior platform for realizing variousn-type GaAs structures. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120679

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We report the observation of single nanotube fragmentation, under tensile stresses, using nanotube-containing thin polymeric films. Similar fragmentation tests with single fibers instead of nanotubes are routinely performed to study the fiber-matrix stress transfer ability in fiber composite materials, and thus the efficiency and quality of composite interfaces. The multiwall nanotube-matrix stress transfer efficiency is estimated to be at least one order of magnitude larger than in conventional fiber-based composites. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120680

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

High-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) have been carried out on Si-doped sintered&agr;-Al2O3.HRTEM shows that there is no amorphous phase at grain boundaries. The Si-segregated boundary is found to be much more sensitive to irradiation damage than undoped Al2O3grain boundaries. AEM with energy dispersive x-ray spectroscopy (EDS) shows the significant segregation of Si at grain boundaries, and AEM with electron energy-loss spectroscopy (EELS) reveals the existence of six-fold coordinated Si at the grain boundaries. The theoretical calculations obtained by the molecular orbital method support the data obtained by EELS. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.120681

出版商:AIP    

年代:1998

数据来源: AIP