摘要:

We describe a unique method for continuously and independently varying the rate‐controlling time constant of excited Yb+3ions in rare‐earth up‐converting phosphors. We show, in the system BaYb2F8: Er, that at all values of the time constant, the power radiated is directly proportional to the square of the observed radiative lifetime, in accordance with the 2‐transfer model of Auzel. The decrease in this time constant arises from the introduction of radiation‐produced defects which selectively affect the Yb+3rather than the activator ions. The phenomenon can be used to study energy transfer from Yb+3to any activator.

ISSN:0003-6951    

DOI:10.1063/1.1654064

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A thermally tunedQ‐switched ruby laser has been used to selectively excite the 6939‐A transition in a potassium plasma. A burst of intensified spontaneous emission at both 6911 and 6939 A has been observed. This enhanced emission contains information on the local properties of the plasma as demonstrated by the observed dependence of the signal duration upon the free‐electron density.

ISSN:0003-6951    

DOI:10.1063/1.1654065

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

We propose that a severe anomaly among the parameters of the gold acceptor state in silicon can be resolved by taking into account the temperature dependence of all the parameters. The temperature variation of most consequence is that of the trap energy level with respect to the band edges. We show that if the trap maintains a constant relative position in the gap, the resulting corrections to the activation energies place the trap nearly 0.1 eV higher in the gap at 300°K than was supposed, and all of the available data are brought into agreement.

ISSN:0003-6951    

DOI:10.1063/1.1654066

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Various effects of postimplantation of silicon ions on boron‐implanted layers are reported. The amount of enhanced annealing depends critically on the target temperature during implantation and on the dose of silicon ions used. At 100 keV, a 5×1015/cm2silicon dose is necessary to create an amorphous layer extending up to the surface at room temperature. Close to 100% of the boron ions located in this layer become electrically active after annealing at 600°C. For boron doses approximately greater than 3×1015/cm2, shallow silicon implantations produce stronger enhanced annealing than expected. For boron doses less than 2×1014/cm2, little or no enhanced annealing is observed.

ISSN:0003-6951    

DOI:10.1063/1.1654067

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The effects of neutron damage on the red and green light output at 300 °K of GaP lightemitting diodes have been examined. The results indicate that the diodes are not sensitive to neutron irradiation in those voltage regions where the radiative current is due to spacecharge recombination in the depletion layer. As a consequence of this, it is shown that the response of the diodes to neutron irradiation can be used to elucidate the radiative currentflow mechanisms in these devices.

ISSN:0003-6951    

DOI:10.1063/1.1654068

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The growth of a carrier wave propagating through a negative‐differential‐mobility semiconducting sample is discussed under nonuniform dc bias conditions. A simple analytical expression for the over‐all numerical gain is given in terms of current density and of the input and output carrier‐wave velocities only. Applications ton‐type GaAs are discussed.

ISSN:0003-6951    

DOI:10.1063/1.1654069

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

This letter describes the production of continuous tone micrographs from the x radiation emitted by a specimen subjected to electron bombardment in a scanning electron microscope. The x rays are collected and energy analyzed with an energy‐dispersive spectrometer so that topographically rough specimens may be examined. The images reveal variations in specimen topography and composition.

ISSN:0003-6951    

DOI:10.1063/1.1654070

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

A mode‐selection technique is described which applies specifically to continuously pumped repetitivelyQ‐switched lasers. The technique is based on opening theQswitch just as the laser gain exceeds theQ‐switch hold‐off loss. This results in a reduction of the number of both longitudinal and transverse modes present in theQ‐switched output. Of particular interest is the simplicity and convenience of this scheme, since it does not require the introduction of any components inside the laser cavity. Experimental data are presented on a continuously pumped repetitivelyQ‐switched Nd: YAlO3laser.

ISSN:0003-6951    

DOI:10.1063/1.1654071

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

The response of reverse‐biased germanium diodes to monochromatic infrared radiation has been studied. Specimens included those fabricated from crystals doped with either copper or gold, or subjected to heat treatment. Preliminary results are reported that show the technique to be useful for identifying such impurities or defects in both lithium‐compensated and high‐purity germanium specimens.

ISSN:0003-6951    

DOI:10.1063/1.1654072

出版商:AIP    

年代:1972

数据来源: AIP

摘要:

Selection of image‐forming electrons that have passed through a small annular zone of the objective lens drastically reduces the resolution‐limiting influence of chromatic aberration. Special objective‐lens aperture diaphragms are needed for this new method of obtaining high‐quality images. The manufacture of the diaphragms is described. High‐resolution and high‐contrast images of crystallographic specimens in the light of selected Bragg‐diffracted beams without preference to azimuthal orientations were obtained. In particular, {111}‐lattice planes of gold were observed as well as interference fringes (``pseudo'' lattice images) between two nonsymmetrical Au {111} diffracted beams, displaying spacings and azimuthal directions characteristic of regular {200}‐ and {220}‐lattice fringes, although the {200} and {220} diffracted beams were omitted by the specific annular aperture used. Such ``pseudo'' lattice images allow deposit orientation determinations in the same way as ``ordinary'' lattice images.

ISSN:0003-6951    

DOI:10.1063/1.1654073

出版商:AIP    

年代:1972

数据来源: AIP