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  • 1
    Electronic Resource
    Electronic Resource
    Quadrupole structure in the rotational spectrum of the v8=1 and 2 and ground vibrational levels of CH3C14N for the frequency range 17–56 GHz (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 4725-4729 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectra in the ground and v8=1 and 2 vibrational states of methyl cyanide have been determined in the frequency range 17–56 GHz. Molecular constants for these vibrationally excited states have been determined from more than 30 observed rotational transitions. Experimentally measured frequencies are presented and compared with those calculated using the results of basic perturbation theory. Constants were obtained for the v8=1 level and these, along with the ground constants, used to generate constants for components of the v8=2 vibration. A model was developed for the quadrupole splitting for the ground and v8=1 levels. From these values spectral components were predicted and assigned for the higher vibration v8=2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452692
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  • 2
    Electronic Resource
    Electronic Resource
    The microwave spectrum of propyne in the 17–70 GHz region for the V10=2 vibrational statef a@f ) (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5-8 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The rotational spectrum of the V10=2 vibrational state of propyne was investigated in the 17–70 GHz region with a total of 18 lines measured. Rotational constants for the V10=2 state have been derived. The rotational constants for the V10=2, V10=1, and ground vibrational states have been compared and the constants of anharmonicity describing the change of B with the level of excitation of the V10 vibrational mode have been derived. The constants derived in this manner are quite different from those calculated by Meyer and Sergent-Rozey based on infrared data. An explanation for this discrepancy is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448736
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  • 3
    Electronic Resource
    Electronic Resource
    High-resolution VUV spectrometer/detector investigations of rare-earth pulsed plasma source (abstract) (1985)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 868-868 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A 1.5-m grazing incidence spectrometer with a channel electron multiplier (CEMA) and electronic readout detector has been incorporated with a rare-earth target, pulsed plasma, continuum source. The spectrometer is compact and portable while maintaining high resolution. The CEMA detector consists of a single multichannel plate (MCP) with coned-shaped input pores which are cut at a 15-degree bias to improve efficiency at grazing angles. The source is a rare-earth plasma generated by a 10-J ruby laser producing intense continuum emission for wavelengths from 170 to 5 nm. This system will be used for both stationary and transient high-resolution atomic photoabsorption spectroscopy. The pulsed plasma source itself will be investigated for suitability as a radiometric transfer standard source. Preliminary results obtained with this integrated system will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138077
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of hydrogen bonding in water clusters through conductivity (dc) measurements of aqueous solutions of NaCl (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 1503-1510 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Conductivity (dc) measurements over the temperature range 273≤T≤360 K of aqueous solutions of NaCl at various concentrations were made and used to establish transport properties of ions in solution. The dynamical properties of the electrolytes were used to establish the nature of the hydrogen bonding in these aqueous systems. Rate equations for ion formation and recombination were used to establish the temperature ranges in which hydrogen bonding dominated in forming polymeric species. Experimental data obtained on the aqueous systems demonstrate that over the range of temperatures 273≤T≤323 K the water system maintains a structure which appears to be independent of solute concentration. This is evidenced by the nearly constant slope in the Arrhenius plot of the data over that range. For the higher range of temperatures, 323≤T≤360 K, the slope of the Arrhenius plot varied more than one order of magnitude for the concentration levels studied. An average value of hydrogen bond energy of 2.8 kcal mol−1 was obtained from the Arrhenius plots for 273≤T≤323 K for samples of pure water. This value was taken for pure water as the slopes remained nearly constant in this range of temperatures for all aqueous solutions but varied systematically with ion concentration over the range of temperature 323≤T≤360 K. If the total range of temperature is chosen, the average value for EHB was found to be 2.5 kcal mol−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.466630
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  • 5
    Electronic Resource
    Electronic Resource
    The microwave spectrum of propyne in the 17 to 72 GHz region for the v9=2 vibrational state (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 6940-6944 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Some rotational components in the v9=2 vibrational state of propyne have been determined in the frequency range 17–72 GHz. Molecular constants for this vibrationally excited state have been determined from more than 11 observed rotational transitions. Experimentally measured frequencies are presented and compared with those calculated using the results of basic perturbation theory. A constant set was obtained for the v9=1 and v9=2 vibrationally excited levels using the experimental data obtained for the ground and these two vibrational levels. Agreement was found to be quite good for all except one component which may be perturbed by combination bands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451380
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  • 6
    Electronic Resource
    Electronic Resource
    Capacitance properties in n-type AlxGa1−xAs (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2414-2416 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electrical properties of n-type AlxGa1−x As, for x〉0.2, are governed by deep donor states (formerly called DX centers) created by the isolated donor atoms. We have studied the capacitance properties of such layers for Si and Sn dopants. The meanings of the capacitance-voltage carrier profiling and of the capacitance dependence with temperature have been considered. The deep donor energy position with respect to the Γ minimum has been determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102031
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  • 7
    Electronic Resource
    Electronic Resource
    Multiple quantum well optical waveguides with large absorption edge blue shift produced by boron and fluorine impurity-induced disordering (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 1373-1375 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Impurity-induced disordering of GaAs/AlGaAs multiple quantum well waveguide structures has been carried out using the neutral impurities boron and fluorine, introduced by ion implantation and followed by thermal annealing. Substantial blue shifts (up to 100 meV) in the absorption edge have been obtained and, for similar conditions, fluorine-induced disordering produces larger shifts than boron-induced disordering. Optical transmission measurements performed in slab and rib waveguides indicate that the additional contribution to the absorption coefficient associated with boron disordering is 15 dB cm−1 and with fluorine disordering is only 6 dB cm−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101597
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  • 8
    Electronic Resource
    Electronic Resource
    Application of intermixing to p-type GaAs/AlAs distributed Bragg reflectors for series resistance reduction in vertical cavity devices (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 4921-4926 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we experimentally investigate the application of selective interdiffusion to p-type (Zn doped) distributed Bragg reflectors, as employed within a range of vertical cavity devices, as a means of lowering the series resistance. Various rapid thermal anneal temperatures and times are studied, both with and without silica encapsulants. The degree of intermixing, and hence series resistance reduction, is found to be cap dependent and this is verified both by secondary ion mass spectrometry and electrical resistance measurements. Both these techniques suggest that the intermixing, due primarily to Zn enhanced interdiffusion, is increased when no encapsulant is used. In this case a series resistance reduction approaching 50% is achieved within the 14 period GaAs/AlAs Bragg reflector. In the silica encapsulated case Ga vacancies are injected into the structure and these suppress the movement of Zn. The resulting Ga diffusion coefficient in this case is found to decrease by a factor of 3 relative to the uncapped case. The effects of interdiffusion on the reflection properties of the reflector, under various anneal conditions, are also described. This has previously been studied theoretically [Floyd et al., J. Appl. Phys. 75, 7666 (1994)] but here we offer experimental evidence on the optical effects of intermixing. We show that the peak reflectivity is found to decrease only slightly with temperature and time, again depending on capping conditions. The major effect contributing to the reflectivity decrease however is surface degradation due to As out-diffusion. The reflectivity does decrease appreciably (∼10%) when the interdiffusion length of the group III atoms becomes a significant fraction of the quarter-wave thickness of the GaAs/AlAs layers, as demonstrated in samples annealed at high temperatures and for long times (960 °C/360 s). These issues, along with that of planar integration of vertical cavity lasers and other devices such as modulators and detectors, are of importance for future applications. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359297
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  • 9
    Electronic Resource
    Electronic Resource
    Capacitance studies of charge redistribution between Γ and X states in a GaAs/AlAs double barrier structure at high pressure (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 7340-7343 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Capacitance measurements as a function of bias provide evidence for the redistribution of electrons above the pressure induced type I to type II transition in a 43, 72, and 40 A(ring) AlAs/GaAs double barrier structure (DBS). Measurements at 77 K for pressures up to 16 kbar allow the identification of low and high pressure regimes. In the low pressure regime the DBS exhibits a capacitance whose characteristic length includes both the barriers and the well, and any surrounding depletion regions. In the high pressure regime, the behavior is like that of a "quantum capacitor,'' with plates only ∼70 A(ring) apart. This causes a marked increase in the zero bias capacitance, which is explained by electron transfer to the X wells in the AlAs regions. The subsequent variation of the capacitance with bias is consistent with a band bending model introduced previously, in which the Fermi level is pinned to the lowest X level in each well at low bias, but where the collector well is eventually depleted at larger bias.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355001
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  • 10
    Electronic Resource
    Electronic Resource
    Hydrogen Balmer alpha line shapes for hydrogen-argon mixtures in a low-pressure rf discharge (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6558-6565 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spectral and spatial profiles of atomic hydrogen emission (the Balmer lines Hα and Hβ) from a low-pressure rf (13.56 MHz) discharge in H2+Ar mixtures have been studied. The plasma emission was observed in a direction normal to the applied electric field. The Hα profiles exhibit central narrow components and wide components which are due to Doppler broadening. Comparisons of the Hα profiles in a pure hydrogen plasma with those in H2+Ar mixtures show that collisions of molecular hydrogen ions and hydrogen atoms with argon atoms play a significant role in the production of the Hα profile shapes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355117
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