摘要:

An ArF excimer laser was used to produce photoelectrons from common metal surfaces at modest vacuum. The photoelectrons are subsequently accelerated across an anode‐cathode gap. Both space‐charge and emission‐limited flow were examined. The temporal characteristics of the emission‐limited electron beam produced by this device are nearly identical to those of the laser pulse used to produce the photoemission. In the space‐charge‐limited case, a rise time of 3 ns was obtained. Maximum current densities of 70 A/cm2were achieved.

ISSN:0003-6951    

DOI:10.1063/1.97532

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

We analyze measurements of the x‐ray reflectivity and photoelectron yield of a Ni‐C multilayer (103 layers;d=31 A˚) in the NiL‐edge region (700–950 eV). The measured reflectivity is shown to be consistent with the one calculated using x‐ray scattering factors  f1and  f2for Ni as obtained from the photoelectron yield (∼f2). The analysis yields a new set of ‘‘effective’’ values for  f1in the NiL‐edge region.

ISSN:0003-6951    

DOI:10.1063/1.97482

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The electro‐optic and dielectric properties of potassium titanyl phosphate (KTP) have been measured from dc to 1 GHz and are compared with other electro‐optic materials. KTP is shown to possess a combination of properties that make it unique for a variety of electro‐optic modulator applications.

ISSN:0003-6951    

DOI:10.1063/1.97483

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

By molecular beam epitaxy we have grown a quarter‐wave stack of lattice‐matched Al0.1Ga0.9As/Ca0.45Sr0.55F2multilayer heterostructures which has high reflectivity (89%) over a broad spectral range. Unlike similar structures of (Al,Ga)As/GaAs which require many periods to achieve high reflectivity, the III‐V/fluoride structures require only four periods due to the large difference in the refractive indices of the III‐V compound and the fluoride (3.6 and 1.4 at 0.9 &mgr;m, respectively). Furthermore, for the (Al,Ga)As/GaAs structures the high‐reflectivity plateau is narrower, and because of absorption in the GaAs layers the reflectivity decreases rapidly at wavelengths shorter than the band‐gap wavelength of GaAs. For the III‐V/fluoride structures grown the absorption is not a problem, and the high‐reflectivity region extends from 0.9 &mgr;m to 0.7 &mgr;m. The ability to grow epitaxial fluoride and (Al,Ga)As with arbitrary AlAs mole fraction, and therefore different refractive indices, should stimulate interesting applications in optics.

ISSN:0003-6951    

DOI:10.1063/1.97484

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Laser emission is obtained at room temperature on the copper I (510.6 and 578.2 nm) and gold I (627.8 nm) transitions from a compact device in which the metal vapor is produced by sputtering in the presence of a rapid flow of noble gas. Peak powers of 1 kW and 250 W are obtained for copper I and gold I, respectively.

ISSN:0003-6951    

DOI:10.1063/1.97485

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Narrow‐bandwidth 193‐nm radiation is generated by stimulated Raman scattering and amplified in ArF to ≊100 mJ in a ≊5‐ns pulse. Two‐photon excitation of H2results in 23 vacuum‐ultraviolet lines down to 117 nm.

ISSN:0003-6951    

DOI:10.1063/1.97486

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A hydrogen‐free SiN film was deposited by ion beam sputtering at low temperature. The substrate surface was almost parallel to the ion beam. The deposited SiN film exhibited high chemical endurance, high thermal endurance, and low density of memory traps.

ISSN:0003-6951    

DOI:10.1063/1.97615

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Laser‐induced sputtering from the (111) surface of BaF2was investigated under ultrahigh vacuum conditions, applying fluences well below the macroscopic damage threshold. Measurement of the wavelength‐dependent desorption of Ba+indicates that Ba+is emitted from two chemically different surroundings at the surface. For a fixed wavelength, the emission rates of Ba+and F+as functions of time show a distinct anticorrelation, confirming the existence of two different chemical states of the surface, and suggesting that the sputtering takes place layer by layer.

ISSN:0003-6951    

DOI:10.1063/1.97487

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Strain in epitaxial BaF2layers grown by molecular beam epitaxy on CaF2covered Si is found to be completely relieved at room temperature in films thicker than ∼250 nm, despite a large lattice and thermal expansion mismatch. In thinner films, planar tensile strain up to 5×10−3is observed. Partial or complete strain relief occurs during temperature cycling near room temperature, and even if further layers are grown on top of the BaF2film. This suggests that such films may be of use as buffers to relieve stresses in heteroepitaxial semiconductor‐on‐semiconductor structures.

ISSN:0003-6951    

DOI:10.1063/1.97488

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

In this work it is found experimentally that the appearance of surfaces in scanning tunneling microscope (STM) images can change drastically as the distance between the STM tip and sample is varied. Defects are found on gold‐sputtered graphite samples which appear as protrusions in charge density when the spacing exceeds a critical value. At smaller distances the protrusions are not evident in the images. It is possible to model these defects as gold atoms which lie just below the surface layer. We discuss possible mechanisms that give rise to the distance dependence.

ISSN:0003-6951    

DOI:10.1063/1.97489

出版商:AIP    

年代:1986

数据来源: AIP