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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 1758-1767 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The CO fundamental vibration–rotation spectra resulting from the interaction of discharged nitrogen with carbon monoxide at low pressure (∼3 mTorr) exhibit bimodal rotational distributions. We have identified 14 vibrational levels of a rotationally relaxed (80 K) component and eight vibrational levels from a rotationally excited component. The eight rotationally excited bands are best reproduced by a statistical distribution E=ER+EV=3.7 eV, which provides sufficient population in the region of the Fortrat reversal (J∼90) to account for the observed R-branch bandhead formation. The rotationally relaxed vibrational levels are populated by single- and two-quantum transfer from N2(v), N2(v)+CO→N2(v−1,2)+CO(v=1,2), and radiative cascade from CO(A) produced by quenching of N2(a'), N2(a' 1Σ−u) +CO→N2(X,v)+CO(A 1Π)→CO(v≤9)+hν, and relaxation of the rotationally excited component. Kinetic and energetic arguments indicate that a branch of N2(a') quenching N2(a' 1Σ−u) +CO→N2(X,v)+CO(v≤14,J) is responsible for the rotationally excited component. Surprisal analysis indicates two dynamic mechanisms are responsible for the rotationally excited component. We have modeled the vibrational distribution of the rotationally excited component with equal contributions from a statistical (all v) process and a process favoring excitation of low vibrational levels (v≤4).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 314-314 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 702-703 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a new method of easily displaying optical-beam-induced contrast (OBIC) images from scanning optical microscopes. The new technique which displays the rectified, differentiated OBIC signal, is insensitive to variations in the background signal level.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 2638-2642 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We calculate the three-dimensional light distribution in the focal region of a lens in the presence of absorption. The results are directly applicable to the optical generation of carriers in a semiconductor. A generation volume for these carriers is introduced and its dependence on focus position is investigated.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1131-1135 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We calculate the beam-induced currents in a semi-infinite Schottky barrier due to arbitrary spatial and temporal excitation. We specialize it to the case where the spatial generation represents optical excitation and the temporal term represents a step function in light intensity. It is shown how, by collecting images at short times after carrier injection before the diffusion process dominates, the resolution of the optical-beam-induced contrast imaging system may be increased.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 191-195 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a model of image formation in scanning optical microscopes operating in the optical beam induced current mode. A perturbation analysis is used, a point spread function is introduced, and specific images of point defects obtained. It is found that the resolution is not limited by the diffusion length.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 2307-2313 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We analyze the effect of the speed of scanning a monochromatic light source across a p-n junction which is perpendicular to the sample surface. It is found that the collected junction current is sensitive to both the magnitude of scan speed and also its direction. This provides a simple method of determining both the minority-carrier-diffusion coefficient and lifetime independently. Scan speeds as small as 10% of the diffusion velocity can significantly modify the form of the junction current versus scan-position curve. The conclusions apply qualitatively to analogous techniques in the scanning electron microscope.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 871-877 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We derive general expressions for the photoluminescence generated within a semi-infinite semiconductor slab by excitation with a focused convergent light beam. A simple Fourier–Bessel transform technique is used to solve the continuity equation. We specialize to the specific cases of excitation pulses which can be described by delta functions and step functions, and consider both finite duration pulses and sinusoidally modulated beams. Conditions are also discussed under which beam focusing and finite beam absorption may be ignored and accurate results still obtained. The results apply to the case of linear recombination mechanisms.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 3383-3385 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report the generation of pulsed optically pumped far-infrared (FIR) radiation with a repetition rate of 200 kHz. These pulses were obtained in a straightforward method by pumping a FIR resonator with a high repetition rate, rf-excited, waveguide CO2 laser. Pulses approximately 50 ns wide were generated both at 432.6 μm in HCOOH, and 117.7 μm in CH2F2. The pulse width of the FIR radiation was studied as a function of the CO2 pulse width, and the relative delay between the two was measured. Based on this data we conclude that the FIR radiation was gain switched and of a duration which was a function of either the gain bandwidth of the FIR transition, or more likely the FIR cavity parameters.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 538-544 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Eleven transitions in the W 3Δu→B 3Πg (W–B) and w 1Δu→a1Πg (w–a) systems of nitrogen have been observed in the infrared including the previously unobserved (1,0) and (2,1) W–B features at 6.5 and 7.65 μm, respectively. The fluorescence spectra were observed in a cryogenic reaction chamber at pressures of ∼3 mTorr (0.4 Pa), following expansion of flowing N2/Ar mixtures excited by microwave discharges at ∼1 Torr. Einstein coefficients for the w–a system, calculated using a published transition moment function, predict the radiative lifetimes of the lower vibrational levels of the w 1Δu state to be a factor of 3 longer than earlier estimates. Using a spectral simulation and linear least-squares fitting technique, the published W–B and calculated w–a branching ratios are verified for the transitions observed across the 2 to 4 μm region. The observed vibrational/electronic state distributions are not characteristic of those expected for direct excitation, but appear to result from extensive collisional coupling among excited states of nitrogen which occurs in the high pressure region prior to expansion.
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