摘要:

Crystals of Li+‐doped MgO which have been quenched from temperatures in excess of 1400 K exhibit an extraordinarily large polarization in an electric field, and the temperature dependence of the relaxation time of this polarization, as measured by both dc (thermal depolarization) and ac (loss tangent versus frequency) methods, indicates a relaxation activation energy of 0.6–0.73 eV, which is consistent with the ionization energy of [Li]° centers. This polarization behavior is to be expected for small semiconductor inclusions (regions of high [Li]° center density embedded in a dielectric) and supports the ’’microgalaxy’’ model of Chenetal. to account for stable [Li]° centers in annealed and quenched MgO : Li+crystals.

ISSN:0003-6951    

DOI:10.1063/1.90431

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We report ballistic phonon experiments in semi‐insulating GaAs as a function of polarization and propagation direction and of the concentration of chromium in the crystal. The data provide direct evidence for a tetragonally distorted site symmetry of the Cr ions and a ground‐state splitting at ∼14 K.

ISSN:0003-6951    

DOI:10.1063/1.90432

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A gap‐coupled InSb/LiNbO3acoustoelectric convolver has been fabricated and tested at 77 K. The results suggest the possibility of using a similar structure with a high‐density InSb diode array as an acoustically scanned infrared imaging device. Measurements indicate that near optimum bias, the convolution efficiency was −63 dBm, the convolution output was uniform along the device length to within 1.5 dB, the insertion loss was 26 dB, the 1‐dB compression point occurred at 18 dBm power input, and the efficiency was constant to ⩽ 3 dB over the range 66–70 MHz.

ISSN:0003-6951    

DOI:10.1063/1.90433

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A discharge technique based on the use of an electron‐beam‐induced plasma return current to produce and heat large‐volume plasmas is described. The results of discharge studies using this technique in attachment‐dominated mixtures are presented. The results are found to be adequately described by a simple theory. The electron attachment rate by F2inferred from these measurements agrees well with those of other workers. KrF laser action at 248 nm is reported in return‐current discharge‐excited mixtures of F2/Kr/He.

ISSN:0003-6951    

DOI:10.1063/1.90434

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The theoretical intensity profile of a phase shift and absorption Fresnel lens in a thin‐film waveguide has been calculated. An experimental lens has been constructed withF=5 and a focal length=4 mm using CeO deposited on a BaO waveguide. A 3‐dB spot size (full width half‐maximum) of 3 &mgr;m was obtained compared to a diffraction‐limited spot size of 2 &mgr;m from theory. Efficiency is approximately 25% and a variation of less than 3 dB in peak intensity is observed over incident angles of up to ±15° from normal.

ISSN:0003-6951    

DOI:10.1063/1.90435

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Saturation of molecular transitions using a tuneable diode laser has been demonstrated for the first time using a standing‐wave‐cavity configuration with the laser beam focused at the sample. Observed saturation effects in NH3transitions near 888 cm−1include sub‐Doppler (Lamb‐dip) resonances at the line center.

ISSN:0003-6951    

DOI:10.1063/1.90436

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Photolytic pumping of the HgCl35(B→X) laser has been demonstrated. Oscillation at 557.6 and 558.4 nm was obtained by irradiating HgCl2vapor and helium with incoherent Xe*2emission at 172 nm from an e‐beam‐excited xenon plasma. Also, by photodissociating HgCl2with ArCl* (175 nm) fluorescence, the HgCl(B) state radiative lifetime was determined to be 22.2±1.5 ns.

ISSN:0003-6951    

DOI:10.1063/1.90437

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Measurements of the rates of collisional quenching of HgCl* (B2 &Sgr;+1/2) by He, Ar, Xe, N2, Cl2, HCl, and CCl4are reported in this paper. Steady‐state measurements are made of HgCl* fluorescence produced by photolyzing HgCl2using Xe2* radiation. A background pressure of [Xe]⩾100 Torr ensures that the HgCl* is vibrationally relaxed and all the quenching measurements are fromv′=0. He, Ar, and N2showed no quenching for pressures <1000 Torr. Xe, Cl2, HCl, and CCl4resulted in two‐body quenching rates of 2.4×10−13, 1.3×10−10, 8.6×10−11, and 1.2×10−10cm3/sec, respectively. These rates are derived by using an estimated HgCl* (B2 &Sgr;+1/2) lifetime of 29 nsec.

ISSN:0003-6951    

DOI:10.1063/1.90438

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The operation of XeF* and KrF* waveguide lasers excited by a capacitively coupled self‐sustained discharge is described. Output energies of 35 and 50 &mgr;J, peak powers of 3.5 and 15 kW, and FWHM pulse widths of 10 and 3 nsec have been obtained for XeF* and KrF*, respectively, with an intrinsic efficiency of 1%. Double‐pulse experiments were conducted to evaluate the repetition rate potential of this device.

ISSN:0003-6951    

DOI:10.1063/1.90414

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Near‐ and far‐field patterns of narrow (⩽10 &mgr;m) stripe‐geometry lasers are reported which differ significantly from the Gaussian patterns predicted and observed in wider‐stripe lasers. The field patterns are explained by using a waveguide model which takes into account the finite extent of the stripe. High‐output‐power operation in a single fundamental transverse and lateral mode (up to 1 W in 25‐ns pulses) has been observed in devices of this type.

ISSN:0003-6951    

DOI:10.1063/1.90415

出版商:AIP    

年代:1978

数据来源: AIP