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  • 1
    Electronic Resource
    Electronic Resource
    Electronic spectra of jet-cooled tropolone. Effect of the vibrational excitation on the proton tunneling dynamics (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 5761-5769 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The laser fluorescence excitation spectra and single vibronic level fluorescence spectra have been measured for jet-cooled tropolone (–OH) and tropolone (–OD). The ν'11(a1), ν12(a1), and ν'19(a2), modes have been newly identified in the excitation spectrum of tropolone (–OH), in addition to the previously observed ν13(a1), ν'14(a1), ν25(b1), and ν'26(b1) modes. The tunneling doublet splittings of these modes in the A˜ 1B2 state have been determined to investigate the effect of the vibrational excitation on the proton tunneling dynamics. The tunneling splitting is highly mode specific. The ν13(a1) and ν'14(a1) skeletal deformation modes are strongly coupled to the proton transfer coordinate and enhance tunneling, whereas the ν19(a2) skeletal twisting mode as well as ν'25(b1) and ν26(b1) out-of-plane bending modes diminish tunneling. The ν'11(a1) C–C stretching and ν12(a1) C–C–C bending modes are considered to be weakly coupled to the proton transfer coordinate, because the tunneling splittings of these modes are similar to that of the zero-point level. The hydrogen/deuterium isotope dependence of the tunneling splitting of the vibronic level has been studied. In contrast with the ν'13 mode, the isotope effect on the tunneling splitting is much smaller in the ν14 mode, although the magnitude of the tunneling splitting of ν'14 is very similar to ν13. This implies that both the average O–O distance and the potential energy barrier are significantly different between these modes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458396
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  • 2
    Electronic Resource
    Electronic Resource
    Selective growth of flowerlike carbon structures by Radio Frequency plasma-assisted pulsed-laser deposition (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 6286-6290 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Selective growth of a novel flowerlike carbon structure is described. These structures are grown on Si (100) substrates coated with Fe2O3 particles. Deposition of carbon is performed by a RF-plasma-assisted pulsed-laser deposition (PLD) technique at 800 °C with pure oxygen as the working gas. The flowerlike carbon structures have 2 to 10 branches spread randomly outward from the center. These structures are constructed from nanoscale graphite crystallites, as revealed by Raman spectroscopy. The Fe2O3 particles oxidize the Si surface where selective growth of the flowerlike carbon occurs with Si–O–C bonds at the interface. We believe that similar bonding might have contributed to the selective growth of multiwalled carbon nanotubes on silicon dioxide. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1458934
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of atomic hydrogen on the growth reactions of amorphous boron films in a low-pressure B2H6+He+H2 plasma (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 1878-1884 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The activation energy (E) of the growth reactions of boron films in plasma-assisted chemical vapor deposition from B2H6+He+H2 at a pressure of 300 Pa was measured at a range of substrate temperature from 750 to 1200 K. It was found that the E decreases continuously from 1.83 to 0.54 kcal/mol and then increases up to 4.97 kcal/mol with the increase of partial pressure of atomic hydrogen ([H]). The continuous change of E is supposed to be due to the transition of the dominant rate determining growth reaction, which is accompanied with the change of the composition of adsorbed layer on a film surface. The variation of E as a function of [H] can be explained with a kinetic model proposed here, in which the E of the growth reaction through BH3 is assigned to 1.83 kcal/mol, that through BH2 to 0.54 kcal/mol, and E of migration of BH2 on the film surface covered with hydrogen is related to be 4.97 kcal/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.341738
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  • 4
    Electronic Resource
    Electronic Resource
    Data-acquisition system for a thermal desorption spectrometer (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 958-960 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A data-acquisition system for a thermal desorption spectrometer (TDS), based on a 16-bit personal computer, has been fabricated. The special features of this system are that calibration of a quadrupole mass spectrometer in the TDS is automatically done and that two mass peaks with same mass number can be separated easily for hydrocarbon-rich materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140355
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  • 5
    Electronic Resource
    Electronic Resource
    Nonmagnetic contrast in scanning Lorentz electron microscopy of polycrystalline magnetic films (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 7677-7681 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of the probe beam defocus on scanning Lorentz electron microscopy images has been investigated. Wave optical analyses show that, given a finite defocus, the variation of the transmission amplitude across the illuminated area on the specimen causes nonmagnetic contrast in the differential phase contrast (DPC) images. This nonmagnetic contrast depends on the sign and the amount of defocus. Since this contrast is virtually proportional to the gradient of the transmission amplitude, it should appear similar to the differentiated contrast of the bright-field scanning transmission electron microscope (STEM) image. Therefore, the nonmagnetic noise appearing in the defocused DPC image can be substantially reduced by subtracting a suitably weighted differentiated bright-field STEM image of the same area. This noise reduction procedure has been demonstrated by applying it to the unintentionally defocused DPC image of a recorded longitudinal magnetic storage medium. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.358466
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of excitation and coherent amplitude enhancement of surface acoustic waves by the phase velocity scanning method (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 6511-6522 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a general theoretical formulation for the characteristics of surface acoustic waves (SAW) generated by the phase velocity scanning (PVS) method that employs a scanning single laser beam (SSB) or a scanning interference fringes (SIF). In the SSB approach, a broad band SAW pulse is generated and its amplitude is coherently enhanced when the laser scanning velocity V is equal to the phase velocity νR of the SAW. The amplitude of the SAW follows a resonance curve represented by a sinc function of the scanning velocity V, but different spatial frequency components in the SSB significantly suppress the side lobes of the resonance curve. In the SIF approach, the scanning velocity νf of the fringes is determined by the intersection angle and the frequency difference ωa of the laser beams. A narrow band tone burst of SAW with frequencies higher than 100 MHz can be excited. The SAW frequency ω depends upon a characteristic time t*, defined as a propagation time of the SAW across the laser beam spot. The SAW frequency ω is identical to the frequency difference ωa when the laser pulse width T is longer than the characteristic time t*. But, the SAW frequency ω is determined as a product kfνR of the wave number of the SIF and the SAW velocity when the laser pulse width is shorter than the characteristic time. Precise frequency measurement provided by the amplitude enhancement effect and the narrow frequency bandwidth in the SIF approach make the PVS method particularly promising for the noncontact SAW velocity measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355140
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  • 7
    Electronic Resource
    Electronic Resource
    Quantification of local remanence magnetization in perpendicular magnetic recording film by scanning interference electron microscopy (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 1485-1487 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The local remanence magnetization of perpendicular magnetic recording bit patterns has been quantified by scanning interference electron microscopy. When two coherent probes run across each bit, the interference image contrast changes periodically with a unit of h/e (h: Planck's constant, e: electron charge). Our numerical analysis shows that the magnetic field effect on the image contrast is less than 1/1000 that of the magnetization under the experimental conditions. This allows the local remanence magnetization of the film to be determined accurately by averaging the periodic contrast change measured over repetitive bit patterns. From the interference image of bit patterns on a Co (0.4 nm)/Pt (1.2 nm)×18 layered film, a value of 1.4×10−8 T m was obtained as the product of the remanence and the film thickness. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.368213
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal growth and the nonlinear optical properties of 4-nitrophenol sodium salt dihydrate and its deuterated material (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3975-3980 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Large organic ionic crystals on the order of a few centimeters of 4-nitrophenol sodium(:Na) salt dihydrate (NPNa) and DNPNa, in which the water of crystallization of NPNa was deuterated, were grown for second-harmonic generation (SHG). The Vickers hardness and thermal conductivities of NPNa were about two times larger than those of conventional organic molecular crystals. The effective nonlinear optical constants of NPNa and DNPNa were estimated to be 5.0 and 5.5 pm/V, respectively. The optical loss coefficients, measured by spectrophotometry, of NPNa and DNPNa were 1.8 and 0.6 dB/cm at 1064 nm, respectively. The substitution of D2O for H2O in NPNa crystal is very effective in reducing the optical loss coefficient. High power of 4.4 mW green SH light was obtained using a 1.5-mm-thick DNPNa crystal as the intracavity SHG device of a diode-pumped Nd:YVO4 laser.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357370
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  • 9
    Electronic Resource
    Electronic Resource
    Surface and step reconstructions on {100} and {111} planes of diamonds prepared by combustion-flame deposition (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 4920-4924 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The growth steps were observed on both {100} and {111} planes of diamonds prepared by a combustion-flame deposition method using C2H2-O2. The etch pits on {100} planes of diamonds were also observed with a scanning electron microscope. The orientations of both growth steps and etch pits on {100} planes were parallel to 〈110〉, whereas the step directions on {111} planes were [1¯1¯2]-oriented and the lateral growth rate was the slowest in the [1¯1¯2] direction. The former is described with the hypothesis of so-called (2×1) surface reconstruction, and the latter is successfully explained by a step reconstruction model. The occurrence of the surface reconstruction would indicate that not only atomic hydrogen but also OH radicals and atomic oxygen, which adequately exist in the diamond growing region in a flame, prevent the surface from being passivated or adsorbed by impinging atoms and/or radicals under the growing conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350640
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  • 10
    Electronic Resource
    Electronic Resource
    Mössbauer studies on tin-bismuth oxide CO selective gas sensor (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 2000-2005 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Tin-bismuth (Sn-Bi) oxide films prepared by spray-pyrolysis techniques were characterized by in situ conversion electron Mössbauer spectrometry in an atmosphere of CO and CH4. The isomer shift of Sn4+ in Sn-Bi oxide decreased at 250 °C and 400 °C in CO and CH4 atmospheres, respectively. An electrical resistance change was also observed at about 250 °C in CO atmosphere, which showed a selective behavior towards CO gas in comparison to CH4 and C2H5OH gases. These results show that CO gas interacted with bulk as well as with the surface of Sn-Bi oxide at low temperature. The increase in the sensitivity of CH4 and C2H5OH at temperatures around 400 °C at the expense of selectivity towards CO was interpreted in terms of surface as well as bulk interactions, and also the catalytic enhancement by reaction of decomposed products from CH4 and C2H5OH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351164
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