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  • 1
    Electronic Resource
    Electronic Resource
    Vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 clusters (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5268-5277 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The first excited electronic state (S1) vibrational dynamics of aniline(Ar)1 and aniline(CH4)1 van der Waals (vdW) clusters have been studied using molecular jet and time resolved emission spectroscopic techniques. The rates of intramolecular vibrational energy redistribution (IVR) and vibrational predissociation (VP) as functions of vibrational energy are reported for both clusters. For vibrational energy in excess of the cluster binding energy, both clusters are observed to dissociate. The dispersed emission spectra of these clusters demonstrate that aniline(Ar)1 dissociates to all energetically accessible bare molecule states and that aniline(CH4)1 dissociates selectively to only the bare molecule vibrationless state. The emission kinetics show that in the aniline(Ar)1 case, the initially excited states have nanosecond lifetimes, and intermediate cluster states have very short lifetimes. In contrast, the initially excited aniline(CH4)1 states and other intermediate vibrationally excited cluster states are very short lived (〈100 ps), and the intermediate cluster 00 state is observed. These results can be understood semiquantitatively in terms of an overall serial IVR/VP mechanism which consists of the following: (1) the rates of chromophore to vdW mode IVR are given by Fermi's golden rule, and the density of vdW vibrational states is the most important factor in determining the relative [aniline(Ar)1 vs aniline(CH4)1] rates of IVR; (2) IVR among the vdW modes is rapid; and (3) VP rates can be calculated by a restricted vdW mode phase space Rice–Ramsberger–Kassel–Marcus theory. Since the density of vdW states is three orders of magnitude greater for aniline(CH4)1 than aniline(Ar)1 at 700 cm−1, the model predicts that IVR is slow and rate limiting in aniline(Ar)1, whereas VP is slow and rate limiting in aniline(CH4)1. The agreement of these predictions with the experimental results is very good and is discussed in detail.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457572
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  • 2
    Electronic Resource
    Electronic Resource
    Salt-dependent binding of Escherichia coli RNA polymerase to DNA and specific transcription by the core enzyme and holoenzyme (1987)
    s.l. : American Chemical Society
    Biochemistry 26 (1987), S. 3322-3330 
    Details
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/bi00386a012
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  • 3
    Electronic Resource
    Electronic Resource
    Compact directional coupler switches using quantum well electrorefraction (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 55 (1989), S. 2280-2282 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have utilized excitonic electrorefraction in reverse-biased InGaAsP/InP quantum well heterostructures to produce directional coupler switches with active lengths under 600 μm operating at 1.3 and 1.55 μm wavelengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.102037
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  • 4
    Electronic Resource
    Electronic Resource
    Signal processing for an infrared array detector (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2920-2923 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband detection scheme for a time-resolved infrared absorption spectrometer, based on a multielement mercury-cadmium-telluride (MCT) array, has been successfully implemented. The spectrometer achieves a resolution on the 10-ns time scale despite the much larger time constant characteristic of the MCT elements. Our signal-collection circuitry takes advantage of the slow decay by integrating the detector response to pulsed IR radiation. The dynamic range is 100–1 and the resultant noise level is near the detector limit. Data acquisition for the 120 elements is fast enough to allow scan rates of 30–40 Hz. The completed electronics are sufficiently compact to be situated local to the array detector, and the design is relatively inexpensive to construct using commonly found electronic components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141079
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  • 5
    Electronic Resource
    Electronic Resource
    An amplified tunable picosecond dye laser based on an active-passive mode-locked Nd:YAG laser (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 2592-2595 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An amplified tunable picosecond dye laser has been constructed which is pumped by an active-passive mode-locked Nd:YAG laser. The laser is tunable from 555 nm to 〉700 nm. It provides a maximum of 2-mJ pulses with pulse widths of ∼17 ps (FWHM). The tuning range can be extended by frequency doubling and/or mixing with the residual 1064-nm pulses. The dye laser is very stable and relatively inexpensive to construct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140676
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  • 6
    Electronic Resource
    Electronic Resource
    Frontiers, Settlements, and Development in Folklore Studies, 1972-1985 (1986)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Anthropology 15 (1986), S. 437-460 
    Details
    ISSN: 0084-6570
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Ethnic Sciences , Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.an.15.100186.002253
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  • 7
    Electronic Resource
    Electronic Resource
    Complex-induced proximity effects: remote lithiations of carboxamides (1987)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 5403-5412 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00252a016
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  • 8
    Electronic Resource
    Electronic Resource
    Effects of thermal annealing on semi-insulating undoped GaAs grown by the liquid-encapsulated Czochralski technique (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 2203-2209 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Recently, a number of studies have reported a correlation between variations in threshold voltage of field effect transistors and the nonuniformity of the luminescence efficiency of semi-insulating GaAs crystals grown by the liquid-encapsulated Czochralski technique. The changes in luminescence efficiency and subsequently the variations in threshold voltages were dramatically reduced by postgrowth annealing of the GaAs crystals under a variety of conditions. In this study, we employ the technique of spatially resolved cathodoluminescence (CL) to carefully examine the changes in luminescence efficiency due to postgrowth annealing. In agreement with previous work, we find that the CL variations are greatly reduced from a factor of ∼2 to ∼5% by thermal annealing at 800 °C for 30 h or at 1200 °C for 6 h followed by slow cooling. The latter thermal treatment is the same as that experienced by crystals during growth by the horizontal gradient freeze (HGF) technique. The extremely uniform luminescence efficiency of HGF crystals is thus believed to be a result of the thermal treatment during growth. Using evacuated sealed ampoule annealing in the temperature range of 550–650 °C, we show for the first time that improvements in CL uniformity are a result of a diffusion process which involves an As vacancy. Due to the dependence on As loss, values of the diffusivity (D) depend on the surface conditions. Values of D=9×106 exp(−2.6 eV/kT) cm2/s and D=1×107 exp(−2.5 eV/kT) cm2/s are obtained for polished and as-cut surfaces, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334363
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanical damage induced luminescence band in GaAs (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 1387-1390 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In this paper we report the observation of a new luminescence band at ∼1.4 eV in the low temperature (10 K) spectrum from bulk GaAs crystals when they are subjected to surface damage by saw cutting, mechanical polishing, and scribing. The band is observed in all crystals, independent of the growth method, dopant, and conductivity type. The peak position of the 1.4-eV band shifts to lower energy with decreasing excitation intensity by as much as 7 meV per decade change in excitation power. The luminescence quenches thermally above ∼30 K with an activation energy of 33±7 meV. We suggest that this new luminescence is a donor-acceptor pair transition involving defects introduced by the surface damage. The mechanical damage, as monitored by the intensity of the luminescence band, is found to extend into the crystal by 10–20 μm depending on the severity of the damage, and it anneals out at (approximately-greater-than)400 °C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334492
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  • 10
    Electronic Resource
    Electronic Resource
    Pseudo-allelic relationship between non-homologous genes concerned with biosynthesis of polyglycerol phosphate and polyglycerol phosphate teichoic acids in Bacillus subtilis strains 168 and W23 (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 3 (1989), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A 60 kbp region of the Bacillus subtilis chromosome encompassing the genes concerned with teichoic acid biosynthesis has been subjected to physical analysis. No homo logy was detected by Southern hybridization between DNA segments encoding the tag genes of strain 168, concerned with polyglycerol phosphate (poly(groP)) biosynthesis, and the tar genes of strain W23, concerned with polyribitol phosphate (poly-(rboP)) biosynthesis. Analysis of 168/W23 interstrain hybrids that incorporate poly(rboP) instead of poly-(groP) into their cell walls revealed that, in every case, Integral substitution of the W23 tar genes for the 168 tag genes had occurred. Interstrain hybrids of the‘W23-like’type have inherited larger segments of W23 DNA than interstrain hybrids of the‘mixed’type. The tag and tar genes are located at equivalent positions on the chromosomes of strains 168 and W23, behaving, in genetic crosses, like an allelic pair. They provide the first example of a pseudo-allelic relationship between non-homologous genes in B. subtilis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1989.tb00166.x
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