摘要:

Computer models of the CO2‐N2‐He laser system usually predict that 20%–33% of the discharge energy should be available as radiation output. Using a comprehensive kinetics model to study vibrational temperatures and stored energies, we find a deterioration in laser efficiency with increasing input energy, due to electron superelastic losses during the excitation pulse. Experimental observations support the calculated vibrational temperatures and likewise our predicted 8%–12% yield efficiency at optimum excitation is in good agreement with the values realized in working lasers.

ISSN:0003-6951    

DOI:10.1063/1.93385

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Ten‐unit individually addressable arrays of constricted double heterojunction large‐optical‐cavity (CDH‐LOC) diode lasers have been realized by one‐step liquid phase epitaxy over channeled substrates, and by bonding to ten‐electrode BeO submounts. Maximum overall powers of 320 mW in cw operation and 3.6 W in pulsed operation (100 ns, 1 kHz) have been achieved. Device interspacing is 150 &mgr;m and thermal crosstalk is of little significance. The devices’ lasing thresholds, near‐field patterns, and power capabilities are highly uniform across the array. This is the first report of a monolithic diode laser array capable of use in multichannel optical recording.

ISSN:0003-6951    

DOI:10.1063/1.93386

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A noncontact transient photoacoustic technique has been developed to monitor a pulsed laser drilling process. Applicaton to the drilling of holes in a composite epoxy‐glass material is presented.

ISSN:0003-6951    

DOI:10.1063/1.93381

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Photoacoustic imaging of microscopic metal film test structures on a surface acoustic wave device at 76‐MHz light modulation frequency is reported. The samples are evaporated on aYZLiNbO3crystal surface and are scanned through the focus spot of a mode‐locked dye laser beam. The optically generated surface acoustic waves are detected by means of a resonant interdigital transducer. Synchronization of the focus spot position to the corresponding piezoelectric signal yields a high resolution photoacoustic image of the samples (lateral resolution 5 &mgr;m).

ISSN:0003-6951    

DOI:10.1063/1.93387

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Photoluminescence emission and excitation spectra of H2S doped into a solid Kr matrix are presented. The results are interpreted in terms of the formation of a KrS excimer formed by photodissociation of the H2S to produce S(1S) and H2. A photodissociation threshold of 7.5 eV (1675 A˚) corresponding to the first vibrationless electronic transition of H2S was observed for the production of S(1S). The results are compared to similar spectra for Kr:OCS observed previously.

ISSN:0003-6951    

DOI:10.1063/1.93388

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have deposited uniform films of Mo, W, and Cr over large areas (>5 cm2) using UV laser photodissociation of their respective hexacarbonyls. The depositions were made at room temperature over pyrex and quartz plates, as well as silicon wafers. We have examined the resistivity, reflectivity, stress, and step coverage of these films.

ISSN:0003-6951    

DOI:10.1063/1.93389

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Nuclear magnetic resonance linewidths are analyzed to provide information on dipole distributions in &bgr;‐polyvinylidene fluoride as a function of poling time in order to establish the contribution of the dipole reorientation mechanism to the time evolution of the piezoelectricd31constant. Results indicate that dipole reorientation proceeds continuously with time and is not uniquely associated with the initially rapid and subsequently slower evolution ofd31with time. It is observed thatd31correlates well with ⟨cos 2&dgr;⟩, where &dgr; is the angle between a typicalbaxis and the poling direction. The magnitude of ⟨cos 2&dgr;⟩ and ⟨4&dgr;⟩ which characterize the remanent polarization indicates that dipole alignment is far from perfect along the poling direction even in the most strongly poled material.

ISSN:0003-6951    

DOI:10.1063/1.93390

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Recent experiments indicate that a phase separation in a spherical sample of the metallic glass Au55Pb22.5Sb22.5occurs near the surface of the sphere. This strongly suggests either a contribution of surface‐free energy to the decomposition process or a possible influence of near surface impurities absorbed during synthesis of the sphere. The surface phase separation has been studied as a function of cooling rate of the sphere. At high cooling rates (small sphere sizes), the surface separation disappears altogether suggesting that the surface of the parent liquid droplet is initially homogeneous.

ISSN:0003-6951    

DOI:10.1063/1.93391

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The electrical properties of P and B implanted and cw CO2laser annealedn‐ andp‐type Hg1−xCdxTe (x=0.21, 0.29) are studied. Hall, conductivity, and capacitance‐voltage (C‐V) measurements carried out on the virgin, implanted, and annealed samples all show that both donor and acceptor implants can be electrically activated when annealing with a cw CO2laser (0.3 s, 250 W/cm2) is employed.

ISSN:0003-6951    

DOI:10.1063/1.93392

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The mobility, lifetime, and capture cross sections for the trapping of electrons and holes at dangling bond defects ina‐Si:H are measured using time‐of‐flight transient photoconductivity. The magnitude obtained for the product &mgr;&tgr;Nsis 3.5×108±25% cm−1 V−1and 4×107±50% cm−1 V−1for electrons and holes, respectively. The capture cross section is 4×10−15cm2for electrons and about 2×10−15cm2for holes. The results are consistent with the amphoteric nature of neutral dangling bonds.

ISSN:0003-6951    

DOI:10.1063/1.93400

出版商:AIP    

年代:1982

数据来源: AIP