摘要:

The phenomenon of ruby laser‐induced breakdown in liquids is investigated by high‐speed holography. The advantage of using holography instead of ordinary photography lies in the possibility to easily suppress the bright white light emitted during the breakdown process. This light constitutes an incoherent background on the holographic plate and does not reproduce upon reconstruction of the recorded scene.

ISSN:0003-6951    

DOI:10.1063/1.89495

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Ultrafine chromium particles prepared by evaporation in argon + air are found to be highly absorbing over the solar spectrum and highly transparent in the infrared. Such spectral selectivity is the distinctive feature of a coating in an efficient photothermal converter for solar energy. Optical transmittance through coatings with mass density ≲0.5 g/m2agrees well with calculations based on the Maxwell‐Garnett theory, whereas coatings with larger mass density exhibit a transmittance too low to be directly reconciled with this theory.

ISSN:0003-6951    

DOI:10.1063/1.89496

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

It is suggested that quantum‐mechanical tunneling might be used in some instances to provide efficient two‐body collision formation of quasibound molecular states suitable for exciplex laser systems. Some evidence for the existence of the necessary bumps in the molecular potential curves is discussed, and it is noted that potential bumps of the general magnitude and width required are apt to be produced whenever an appreciable cross section exists for endothermic excitation transfer from a metastable state of one gas to an excited state of another gas.

ISSN:0003-6951    

DOI:10.1063/1.89497

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

High‐power cw laser radiation from nine Ar and five Kr laser transitions in the spectral range 275 <&lgr;<365 nm has been generated in a highly ionized low‐pressure dc discharge. The output increases without saturation up to the maximum available discharge current of 480 A˚. The most intense emission is 61 W obtained from the combined 351.1‐ and 363.8‐nm Ar III lines.

ISSN:0003-6951    

DOI:10.1063/1.89498

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Near‐ultraviolet absorption spectra for the I(1/2)u→II(1/2)gtransition have been calculated for Ne+2, Ar+2, Kr+2, and Xe+2usingabinitioconfiguration interaction methods. The spectra are all similar except that the position of maximum absorption shifts to longer wavelength for the heavier rare gases. The absorption cross sections are tabulated at the wavelengths of the KrF, XeBr, XeCl, and XeF lasers.

ISSN:0003-6951    

DOI:10.1063/1.89499

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Metallic pads on optical fibers are heated by the absorption of light at the 1‐&mgr;W–10‐mW power level. Due to differential thermal expansion, the fibers bend, and, by misaligned coupling, modulate guided light signals. An optically operated relay, a narrow‐band audio‐frequency resonator, and a self‐commutating optically powered oscillator are demonstrated.

ISSN:0003-6951    

DOI:10.1063/1.89500

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Operation of a XeF laser at high spectral power densities on transitions within a single vibrational band has been demonstrated. An electron‐beam‐controlled discharge XeF laser was operated as an injection‐locked regenerative amplifier. A narrow‐band signal from an e´talon‐tuned XeF laser was used to lock the regenerative amplifier. Competition between the various components of the emission spectrum was observed. Homogeneous extraction is observed within each vibrational band, indicating that the rotational cross‐relaxation time is substantially faster than the radiative lifetime of XeF. Coupling between vibrational bands was not observed. These measurements indicate that the efficient extraction from XeF on a single rotational transition should be possible. The band at 351 nm was found to consist of components arising from at least two different vibrational bands. The transitions in the 353‐nm band and one component of the 351‐nm band share a common vibrational level in the upper electronic state. These observations are consistent with current vibrational assignments of the XeF spectrum.

ISSN:0003-6951    

DOI:10.1063/1.89501

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

A trapping layer of W (≈1014atoms/cm2) has been deposited between 70 A˚ of thermal silicon dioxide grown from a polycrystalline silicon substrate and 520 A˚ of deposited pyrolytic silicon dioxide in an MOS structure to reduce high leakage currents and low‐voltage breakdowns associated with asperities at the polycrystalline Si–thermal SiO2interface. MOS structures without the W layer but with the pyrolytic SiO2layer were also found to be effective. This improvement is ascertained to be due to localized electron trapping in the W or pyrolytic oxide layer at low average fields which reduces the locally high fields and therefore high dark currents associated with the asperities. At higher average fields uniform trapping is believed to be dominant. This uniform effect can also enhance the breakdown characteristics if the trapped charge is not detrapped by the applied field.

ISSN:0003-6951    

DOI:10.1063/1.89502

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

We have used the DLTS capacitance spectroscopy technique to search for interface states associated with an LPE GaAs/Al0.22Ga0.78As heterojunction. The results can be interpreted in terms of well‐known deep bulk states shifting abruptly at the interface with no observable interface states. The limiting values are <5×108and <4×109cm−2interface states (deeper than 0.1 eV) in the upper and lower half of the gap, respectively.

ISSN:0003-6951    

DOI:10.1063/1.89503

出版商:AIP    

年代:1977

数据来源: AIP

摘要:

Hall‐effect measurements as a function of temperature on nitrogen‐containing GaAs1−xPxhave shown that the nitrogen isoelectronic trap in these materials can be best described by a bound state in the band gap, occupied by electrons according to the equilibrium thermal distribution. It is shown that the presence of nitrogen can have a pronounced effect on the free‐carrier density. Our results are in excellent agreement with recent optical data.

ISSN:0003-6951    

DOI:10.1063/1.89504

出版商:AIP    

年代:1977

数据来源: AIP