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  • Articles: DFG German National Licenses  (62)
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  • Articles: DFG German National Licenses  (62)
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  • 1
    Electronic Resource
    Electronic Resource
    Multinuclear nonmagnetic resonance studies of perfluoro poly ether lubricants (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 6161-6161 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Commercial perfluoro poly ethers (PFPE) are available with different backbone structures and end groups and are being used as lubricants for particulate/thin film disks. Very little published information is available other than F-19 spectra for these polymers.1 In this abstract a systematic study was undertaken to study the structure of these PFPE polymers using multinuclear magnetic resonance (NMR). Backbone structural differences of Z. Fomblin, Y. Fomblin, Krytox, and Demnums could be clearly seen from F-19 NMR studies. Number average molecular weight of PFPE polymers was also determined from F-19 NMR and found to be between 2000 and 10 000. C-13 NMR was used to differentiate the end group from backbone structure. Associated proton test (APT) was used to distinguish the primary, secondary, and tertiary carbons. The proton connectivity of end group (e.g., Fomblin AM2001) was studied by two dimensional (2D) proton correlation spectroscopy (COSY). The connectivity of a hydrogen containing end group to the backbone was studied by heteronuclear shift correlation spectroscopy (HCORR). Even though these PFPE polymers have low vapor pressure, a significant amount of lube loss is found over a period of time under HDA (head disk assembly) conditions.The temperature could increase from 25 to 60 °C. Additionally under certain asperity/head interaction conditions the temperature variation could be as high as 300 °C to 500 °C. It is also reported that functionalized polymeric materials (e.g., Krytox 143 AC) can be bonded to magnetic disk surface by applying heat. The effect of temperature on lubricant volatility/stability was studied for AM 2001. The molecular weight of heat treated AM 2001 (90 min at 130 °C) changed from 2100 to 4500. This could be due to preferential volatilization of low molecular weight fragments. NMR analysis showed significant conversion of piperonyl end group to -CH2OH. Thus AM 2001 is not thermally stable. Precipitation was also found to occur when AM 2001 is stored over a period of time. The precipitate is found to be a derivative of 9,10 dihydroanthracene. Unlike other PFPE polymers AM 2001 is found to be sparingly soluble in dichloromethane (contrary to the claim by the manufacturer that it is soluble only in fluorinated solvents) and hence more polar than Fomblin Z-Dol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355443
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A new particle size distribution (1982)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 21 (1982), S. 776-778 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i200019a039
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Model for nonpremixed fuel-air combustion in fluidized beds (1984)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 23 (1984), S. 313-319 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i200025a022
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Measurement of bubble size in fluidized beds (1984)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 23 (1984), S. 573-576 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i200026a028
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on mixing time in bubble columns with pseudoplastic (carboxymethyl)cellulose solutions (1987)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 26 (1987), S. 82-86 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00061a015
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Studies on gas holdup and bubble parameters in bubble columns with (carboxymethyl)cellulose solutions (1987)
    s.l. : American Chemical Society
    Industrial & engineering chemistry research 26 (1987), S. 86-91 
    Details
    ISSN: 1520-5045
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ie00061a016
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Elastic anomalies of barium titanate (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 945-954 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The anomalies of the second-, third-, and fourth-order elastic constants have been derived for barium titanate and related compounds for the phase transition from cubic to tetragonal and from the tetragonal to the orthorhombic phases. The equilibrium values of the three components of the order parameter and the strain variables in the two phases have been obtained from the stability conditions. The fluctuations in the order parameter in the two phases have been derived from the Landau–Khalatnikov equations. Expressions have been given for the shift in the zero point energy in the tetragonal and orthorhombic phases, and these are shown to be proportional to (T−Tc)2. The anomalies for all the second-order elastic constants have been derived for both phases, and relations among them have been reported. It is shown that the elastic anomalies suffer a discontinuity at the transition temperature for both the phases. Our expressions give the temperature variation of the third-order elastic and fourth-order elastic constants for the phase transition from the tetragonal to the orthorhombic phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354836
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    The laser photoelectron spectrum of gas phase aniline (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 1741-1749 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An effusive molecular beam of aniline vapor has been two-step ionized by irradiating it with the output from a frequency doubled dye laser. Photoelectrons ejected while exciting several different vibronic levels of its 1B2 electronic state have been kinetic energy analyzed. In all cases ions are found to be generated in their ground electronic state. Their vibrational state distribution is strongly wavelength dependent and differs remarkably from that obtained in conventional single photon photoelectron spectroscopy. The energies of several in-plane vibrational modes of aniline cations have been measured. In contrast with the ground electronic state of the neutral molecule, the ground state of the ion and 1B2 excited electronic state of the neutral molecule both appear to be nearly planar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448406
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    The laser photoelectron spectrum of gas phase p-difluorobenzene (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 5349-5359 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Gas phase p-difluorobenzene (PDFB) has been laser ionized from several vibronic levels of its 1B2u first excited electronic state. The vibrational state distribution of the ions generated depends on the vibronic level from which ionization occurs. The fundamental frequencies of five symmetric vibrations; ν2, ν3, ν4, ν5, and ν6, and three asymmetric vibrations; ν8, ν29, and ν30, of the lowest electronic state of PDFB+ have been assigned. Effects due to electronic configuration interaction are observed in the photoelectron spectra. Small peaks are also observed in the spectra which may reflect a change in geometry of the ground state cation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456441
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Ionization of the A(2.SIGMA.+) state of nitric oxide: An investigation of non-Franck-Condon behavior in photoionization (1986)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 90 (1986), S. 5658-5661 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100280a036
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    Paper (German National Licenses)
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