摘要:

Unique acoustic material signatures (AMS) may be obtained in the reflection acoustic microscope. The proposed model shows that they result from interference between two components reradiated into the immerson fluid at the materials critical Rayleigh angle &Vthgr;R. The characteristic period &Dgr;zNof this interference signature varies as the square of the Rayleigh wave velocity and is empirically given by &Dgr;zN=&lgr;R/sin&Vthgr;R, where &lgr;Ris the Rayleigh wavelength. Materials covering a greater than 3 : 1 velocity range agree well with this physical model. Substitution of the longitudinal wave velocity in the expression extends the range of measurable AMS to acoustically slower materials. A variety of applications for AMS is suggested.

ISSN:0003-6951    

DOI:10.1063/1.90741

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The maximum stress intensity factor of a surface crack has been inferred by measuring the reflection coefficient of a Rayleigh wave incident to the crack. An acoustic surface wave wedge transducer was used to excite the incident wave and to measure the reflected‐wave amplitude. The fracture stress of Pyrex glass specimens containing the acoustically measured cracks was determined in biaxial flexure. The values of the fracture stress predicted from acoustic data were found to be in excellent agreement with the measured values, with less than a 15% error.

ISSN:0003-6951    

DOI:10.1063/1.90742

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Multilayer coatings consisting of very smooth ReW and carbon films used as near‐normal‐incidence reflectors show theoretical performance in the 150–200‐A˚ wavelength region and should allow the fabrication of useful normal‐incidence mirrors for wavelengths as short as 50 A˚.

ISSN:0003-6951    

DOI:10.1063/1.90743

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The electron‐attachment rate constant for Cl2has been measured in mixtures of N2/Cl2and Ar/Cl2at room temperature and at 250 °C in an electron‐beam‐controlled discharge. From these measurements and the use of a numerical solution of the Boltzmann equation we have been able to calibrate the relative electron‐attachment cross section of Cl2that has been measured by Tam and Wong and by Kurepa and Belic. The peak value of this cross section that gives the best fit to our data is 2.2×10−16cm2at room temperature.

ISSN:0003-6951    

DOI:10.1063/1.90744

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The experimental study of the multiphoton ionization (MPI) of nitrogen by a neodymium glass laser gives the valuen=13±2 for the nonlinear interaction order and a maximum kinetic energy of 3 eV for the produced charges. An analysis of the multiphoton absorption processes is made taking the experimental results into account.

ISSN:0003-6951    

DOI:10.1063/1.90745

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Reactive‐plasma etching is conventionally carried out using one power supply to both generate the glow discharge and to control the flux and energy of ion bombardment on the substrate. A three‐electrode, or triode, configuration is described in which these two functions are controlled quasi‐independently; results obtained with this arrangement are described. These results are somewhat similar to those obtained with a diode RIE system, except that control of the substrate voltage allows another degree of freedom over etch rates, etch selectivity, and wall profiles.

ISSN:0003-6951    

DOI:10.1063/1.90746

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Valence electronic states of third‐period elements (Al, Si, P, and S) dissolved in Cu were pursued through the chemical effect of the LVV Auger transition from these elements using Auger electron spectroscopy (AES). Indeed, the LVV Auger signals of Al, Si, P, and S in Cu hosts differed completely from those in the pure (metal or semiconductor) states, indicating the presence of the definite chemical effect. The origin of the chemical effect was discussed in connection with similar studies by soft x‐ray spectroscopy (SXS).

ISSN:0003-6951    

DOI:10.1063/1.90747

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Transparent conductive coatings of In1.9Sn0.1O3have been made on fused silica which exhibit damage thresholds of 2.2 and 3.1 J/cm2for 0.15‐ and 1‐nsec Nd : glass laser pulses, respectively. The coatings were made by reactive sputtering in an rf diode system. Coating absorption detected spectrophotometrically was less than 1% (∼300 cm−1) near 1064 nm for coatings with in‐plane resistivities of 0.017 and 0.55 &OHgr; cm. An important potential application for such coatings is as the electrode for electro‐optic shutters based on the longitudinal Pockels effect which are used in high‐energy laser systems.

ISSN:0003-6951    

DOI:10.1063/1.90727

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The power‐conversion efficiency of SnO2/Si solar cells fabricated by electron‐beam evaporation of SnO2is strongly dependent on the angle of incidence of the SnO2vapor stream on silicon. The optimum angle of incidence is between 50° and 70°. Solar cells with power‐conversion efficiencies exceeding 10% have been reproducibly fabricated by depositing the SnO2at angles of incidence in this optimum range.

ISSN:0003-6951    

DOI:10.1063/1.90728

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The behavior of a number of glass and Ti in‐diffused LiNbO3waveguides was investigated as a function of laser power, and the damage thresholds were evaluated and compared to the bulk material values.

ISSN:0003-6951    

DOI:10.1063/1.90729

出版商:AIP    

年代:1979

数据来源: AIP