摘要:

The self‐trapping interpretation of apparent small‐scale filaments has recently been questioned. Experiments were therefore undertaken to test whether the observed filamentary structure is caused by self‐trapping. We found that the filaments propagated over distances of the order of a few centimeters. To confirm this result, the spectral broadening in filaments versus propagation distance was determined. These observations give a nonlinear index change which agrees with the index change calculated from the observed diameter.

ISSN:0003-6951    

DOI:10.1063/1.1652779

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An experiment is described which confirms the theory of the distortion of a cholesteric structure by a magnetic field. Field effects in a sample ofp‐azoxyanisole doped with cholesteryl acetate were viewed directly with a microscope, and the pitch of the helical structure was measured as a function of field strength.

ISSN:0003-6951    

DOI:10.1063/1.1652780

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The localization energy of excitons at N isoelectronic substituents in GaAsxP1−xhas been determined from optical absorption spectra forx≲ 0.2. The results indicate that the binding energy of the N‐induced electron state associated with theX1conduction band minima in GaAs may be relatively large, ∼0.08 eV. However, this state is still more than 0.3 eV above the lowest minimum at &Ggr;1c. It is likely that there is no bound state associated directly with the &Ggr;1conduction band minimum.

ISSN:0003-6951    

DOI:10.1063/1.1652781

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

High‐frequency (MHz) and low‐frequency (kHz) current oscillations are found in photoexcited long GaAs diodes; the threshold field for the former is about 4.0 × 103V/cm, and for the latter is about 1.5 × 103V/cm. At an average applied field >4 × 103V/cm, high‐frequency oscillation occurs first and continues for a while, then low‐frequency oscillation takes place. Experimental results suggest that the origin of high‐ and low‐frequency oscillation are different from each other; the former is the two‐valley transfer effect, and the latter the field‐dependent trapping effect.

ISSN:0003-6951    

DOI:10.1063/1.1652782

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Electron emission into vacuum has been observed from a forward‐biased Cs‐ and O‐treated GaAsp‐njunction. The device was operated at room temperature with dc bias voltage. The effective efficiency of the device (emission current divided by internal diode current eligible for emission) was 0.05%, while the over‐all efficiency of the device (emission current divided by total diode current) was 10−6. The low over‐all efficiency is explained in terms of sample geometry and surface activation.

ISSN:0003-6951    

DOI:10.1063/1.1652783

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Certain amorphous materials exhibit rapid electrical switching. The variation in their capacitance was evaluated as a function of temperature and electric field in the high‐resistance state. The zero‐field capacitance follows a Curie‐Weiss law above room temperature. At low temperatures, and at fields near the threshold of switching for higher temperatures, the open‐circuit incremental ac capacitance becomes negative.

ISSN:0003-6951    

DOI:10.1063/1.1652784

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A high‐temperature aerodynamic molecular‐beam apparatus has been used to investigate the spatial distributions of argon atoms scattered from solid argon at 15°K for incident energies of 0.30 to 0.54 eV and incident angles of 0 to 70 deg. A highly nondiffuse flux of scattered atoms was observed for the noncondensing atoms.

ISSN:0003-6951    

DOI:10.1063/1.1652786

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

PassiveQ‐switching of a CO2laser operating at 10.6 &mgr; has been achieved with a mixture of sulfur hexafluoride and chlorotrifluoroethylene gases contained in a gas cell placed within the resonator. Use of chlorotrifluoroethylene gas to suppress spurious oscillations eliminates the need to use dispersive optical elements in the resonator.

ISSN:0003-6951    

DOI:10.1063/1.1652787

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Optical reflection spectra of crystalline, sputtered, and ion implanted silicon specimens are presented. Characteristic aspects of the spectra of ion implanted specimens are related to lattice damage.

ISSN:0003-6951    

DOI:10.1063/1.1652788

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We have measured the fractional change in the optical reflectivity of silicon in the 1.8–2.2 eV photon energy band as a function of 40‐keV antimony ion dose (1011–1015Sb/cm2at various implant temperatures (− 160–405°C). Approximate agreement is found between the change of reflectivity and previous measurements of lattice disorder as determined by backscattering of 1‐MeV He ions.

ISSN:0003-6951    

DOI:10.1063/1.1652789

出版商:AIP    

年代:1969

数据来源: AIP