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  • 1
    Electronic Resource
    Electronic Resource
    Laser spectroscopy of the ν1+3ν3 absorption band in 12C2H2. I. Pressure broadening and absolute line intensity measurements (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 7954-7960 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have developed a Ti:Sa autoscan laser spectrometer and used it to perform a detailed investigation of individual line profiles in the ν1+3ν3 band of 12C2H2. Pressure self-broadening effects were measured for most lines with J″ values ranging from 0 to 22, and for pressures between 10 and 600 Torr. The high-pressure data points (p〉250 Torr) are fitted satisfactorily by a Voigt profile. Line narrowing, characterized by an underestimation of the Lorentz contribution to the Voigt profile, was observed for the low pressures range (p〈150 Torr), indicating the influence of molecular confinement. The two usual limit models (soft and hard collisions) were fitted to the observed line shapes in order to extract more precise information concerning the pressure broadening. The present results confirm the absence of strong vibrational dependence in the self-broadening coefficients. Absolute line intensities are also determined in the fitting procedure. No significant differences were found for the two pressure domains if the appropriate model in each range is used. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480129
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  • 2
    Electronic Resource
    Electronic Resource
    Laser spectroscopy of the ν1+3ν3 absorption band in 12C2H2. II. Self-collisional lineshift measurements (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 7961-7965 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have recorded the spectrum of the ν1+3ν3 band in 12C2H2, around 12676 cm−1, using an autoscan Ti:Sa spectrometer. Pressure-dependent line positions were determined from an absorption spectrum recorded using a long White-type multiple-pass cell. An optoacoustic cell with a constant, low acetylene pressure allowed reference line position wavenumbers to be measured simultaneously. In different experiments, the multiple-pass cell was filled with increasing acetylene pressures. Self-collisional lineshifts were determined for more than 30 P and R lines in the band. Line wavenumbers for the stronger lines were separately measured from an optoacoustic spectrum calibrated using the results of a previous investigation in the literature [X. Zhan and L. Halonen, J. Mol. Spectrosc. 160, 464 (1993)] and corrected for their pressure dependence using the presently determined self-collisional lineshifts. Lineshift parameters that are significantly different from the overall behavior in the band are unexpectedly observed for the R(17) and P(19) lines. This result is explained in terms of a different intermolecular behavior of the molecule in the upper J=18 rotation level, attributed to an intramolecular Coriolis-type coupling with a nearby state tentatively assigned as containing important excitation in ν5, the cis-bend mode. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480130
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  • 3
    Electronic Resource
    Electronic Resource
    The vibrational energy levels in acetylene. III. 12C2D2 (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 1377-1389 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed the rovibrational analysis of the absorption spectrum of 12C2D2 between 5150 and 8000 cm−1, recorded by Fourier transform absorption spectroscopy, and between 12 800 and 16 600 cm−1, recorded by intracavity laser absorption spectroscopy. Respectively 10 and 9 bands are reported for the first time in each range. Improved or new rovibrational parameters were obtained for 34 vibrational levels altogether. The vibrational energies we obtained, together with those reported in the literature, were taken into account to model the vibrational energy pattern in 12C2D2(X˜ 1Σg+). The analysis was performed in successive steps, inferring each time suitable parameters. The 44/55, 11/33, 12/33, and 1/244 quartic order anharmonic resonances were introduced during the procedure. They altogether define vibrational clusters which are characterized by only two dynamical constants of motion, Ns=V1+V2+V3 and k=l4+l5. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.475352
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  • 4
    Electronic Resource
    Electronic Resource
    Headache and cortisol responses to m-chlorophenylpiperazine are highly correlated (1993)
    USA/Oxford, UK : Blackwell Science Ltd
    Cephalalgia 13 (1993), S. 0 
    Details
    ISSN: 1468-2982
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The serotonin receptor agonist m-chlorophenylpiperazine (m-CPP) stimulates the release of cortisol and prolactin, and induces migraine-like headaches. We have studied the neuroendocrine and headache responses to m-CPP in 8 subjects with migraine and l0 normal subjects. Each subject underwent two challenge tests, one with 0.25 mg/kg PO of m-CPP and the other with placebo, administered in a double-blind crossover format. Serial measurements of serum cortisol, prolactin, and m-CPP levels were made at 30-min intervals for 210 min following ingestion of the medication. The incidence and severity of headache was assessed by a structured telephone interview after each test. We confirmed that m-CPP stimulates the release of cortisol and prolactin, and may induce headache, in both migraine subjects and normal controls. The cortisol response as well as ratings of headache severity and duration directly correlated with plasma levels of m-CPP. There were highly significant associations between the cortisol response and both headache severity and duration, independent of m-CPP plasma levels. We did not find statistically significant differences between the migraine and normal subjects in terms of their neuroendocrine or headache responses to m-CPP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1468-2982.1993.1306400.x
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  • 5
    Electronic Resource
    Electronic Resource
    Concerted reduction of yeast uridine diphosphate galactose 4-epimerase (1971)
    s.l. : American Chemical Society
    Biochemistry 10 (1971), S. 1545-1551 
    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/bi00785a006
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  • 6
    Electronic Resource
    Electronic Resource
    Band offset determination in analog graded parabolic and triangular quantum wells of GaAs/AlGaAs and GaInAs/AlInAs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5004-5011 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The band offset parameter Qc = ΔEc/ΔEg for both GaAs/AlGaAs (lattice matched to GaAs), and GaInAs/AlInAs (lattice matched to InP) was extracted from the optical interband transition energies obtained from both triangular and parabolic quantum well shapes of various widths. The wells were grown using continuous analog compositional grading as opposed to the discrete, superlattice (digital) grading used by previous researchers. Electron beam electroreflectance (EBER) was the primary technique used to measure the interband transition energies. By combining the theoretical energies from quantum mechanical potential well calculations with EBER measured energies, it was possible to extract band offset values in a self-consistent manner. Qc values obtained were 0.658±0.009 and 0.650±0.001 for GaAs/AlGaAs and GaInAs/AlInAs, respectively. Measurements also revealed that Qc was both temperature and concentration independent within the range of composition studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350600
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  • 7
    Electronic Resource
    Electronic Resource
    Heterointerfaces in quantum wells and epitaxial growth processes: Evaluation by luminescence techniques (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 1 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This paper presents a review devoted to the problem of how optical and structural properties of quantum-well heterostructures (QWH) can be correlated in detail, and how these properties may be connected with the parameters of the epitaxial growth process. It demonstrates how luminescence techniques, mainly photoluminescence (PL) and cathodoluminescence imaging (CLI), may be used for evaluation of the structural disorder on the atomic scale, which occurs at the growth surfaces creating the interfaces of the QWH. The physics of the excitonic luminescence in QWH (theory and experiment) is presented in detail in the first part of the review. This is followed by a comprehensive discussion of experimental aspects (hardware and software) of the luminescence techniques, as applied for studying QWH grown by molecular-beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE). The specific features of both the epitaxial growth techniques, when used for growing QWH are presented in the next part of this review. Finally, the possibilities of application of PL and CLI to studies on growth of QWH by MBE and MOVPE are demonstrated on a couple of selected examples. The review concludes with a short discussion on possible interpretation mistakes which may occur when one applies the CLI to studies of interfaces in QWH without taking into account the basic parameters of the excitonic luminescence lines creating the CL images of the relevant interfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349613
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  • 8
    Electronic Resource
    Electronic Resource
    The bending vibrational levels in C2D2 (X˜ 1Σ+g) (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 3407-3414 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Improved sets of data have been recorded and analyzed in order to study the bending rovibrational energy levels of C2D2, in the regions of the ν5–ν4 difference band (FIR) and of the ν5 fundamental band (IR). A matrix model is setup to deal with a Darling–Dennison coupling between sets of bending levels as well as with the usual l-type resonances. A simultaneous fit of the new data together with earlier microwave measurements produces an extended set of very accurate parameters, including for the first time in C2D2 s45 and qkt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459763
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  • 9
    Electronic Resource
    Electronic Resource
    Hg1−xCdxTe-Hg1−yCdyTe (0≤x, y≤1) heterostructures: Properties, epitaxy, and applications (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 2671-2694 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This article presents a review of the state of the art of research and development on Hg1−xCdxTe -Hg1−yCdyTe (0≤x,y≤1) heterostructures important for applications in the modern infrared detection technique. It deals with the fundamental physical properties, epitaxial growth methods, and applications of these structures. The most important experimental results relevant to this subject are described and discussed. Following a short survey of the physical properties of Hg1−xCdxTe, the travelling heater method for growing bulk crystals of Hg1−xCdxTe has been described and compared with the epitaxial growth techniques used to prepare thin films and layered structures of this compound. Some important aspects of substrate preparation procedures related to CdTe wafers have been discussed. Then the most important problems regarding the liquid-phase, vapor-phase, and molecular-beam-epitaxy methods of Hg1−xCdxTe -Hg1−yCdyTe (0≤x,y≤1) heterostructures have been studied. A comprehensive discussion of technology and the parameters of different heterostructure photodiodes made of Hg1−xCdxTe with electrically passive and electrically active heterointerfaces has been presented. The review is concluded with an overview of research problems relevant to HgTe-CdTe superlattices and the surfaces and heterointerfaces of Hg1−xCdxTe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.335408
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  • 10
    Electronic Resource
    Electronic Resource
    Experimental test of the transition layer model of atomic layer epitaxy (1988)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 53 (1988), S. 1396-1398 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thermal desorption experiments concerning Te deposits on GaAs (100) surfaces have been performed using quadrupole mass spectrometry. The results give evidence that near the GaAs surface two regions of different Te adsorption can be distinguished. The first region nearest to the substrate surface consists of Te adparticles, which are chemisorbed to the substrate reevaporating at temperatures above 510–520 °C. The adparticles of the second physisorbed region begin to desorb at 350–360 °C, which is still considerably higher than the desorption temperature of the bulk Te deposits. The approximate thicknesses of these two regions are 1–2 monolayers and 3–10 monolayers of Te, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.99988
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