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  • 1
    Electronic Resource
    Electronic Resource
    The Na2 a 3Σ+u state. Rotationally resolved OODR 3Πg–a 3Σ+u fluorescence spectroscopy (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 1178-1182 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Thirteen bound vibrational levels (v=0–12) and a portion of the continuum of the Na2 a 3Σ+u state have been observed in rotationally resolved fluorescence spectra from single rotation-vibration levels of two 3Πg states. These 3Πg states were populated by A 1Σ+u∼b 3Πu perturbation-facilitated optical–optical double resonance from the X 1Σ+g state. Analysis, using a LeRoy–Bernstein long-range expression for the energy levels, produced an RKR potential curve from which were derived, in combination with recent results obtained by Barrow et al. on the X 1Σ+g state, principal constants for the a 3Σ+u state of re=5.0911(30) A(ring), De=174.45(36) cm−1, ωe=24.47(21) cm−1, and Te=5848.21(35) cm−1. In addition, the exchange interaction between two ground state Na atoms was found from the difference between the X 1Σ+g and a 3Σ+u potential curves to be well represented by an exponential, A exp(-BR), A=9.44(71)×105 cm−1, B=1.448(14) A(ring)−1 for R(approximately-greater-than)5.0 A(ring).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448490
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  • 2
    Electronic Resource
    Electronic Resource
    Picosecond pulse amplification by wave mixing in GaAs (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 1953-1955 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Pulses at 1.064 μm were amplified up to 102 times by nonlinear mixing with a coherent pump wave in GaAs. The observed amplification shows a strong dependence on the intersection angle and time delay between pump and probe pulses. The effect is discussed in terms of self-diffraction by a laser-induced free-carrier grating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.101204
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  • 3
    Electronic Resource
    Electronic Resource
    The origin of hard magnetic properties in rapidly quenched Nd4Fe77.5B18.5 alloy : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6980-6982 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Until now, the origin of hard magnetic properties of rapidly quenched Nd-Fe-B alloys with lower Nd concentration is not clear. In this paper, the phase compositions of rapidly quenched Nd4Fe77.5B18.5 alloys annealed under different conditions have been studied by using zero-field spin-echo nuclear magnetic resonance (NMR) and Mössbauer effect (ME) techniques. It is found that there exists a certain amount of Nd2Fe14B phase in the samples annealed at 960 °C and ingot alloy, which have poor hard magnetic properties; while, the sample annealed under optimal condition consists only of bct-Fe3B as the main phase and a small amount of a-Fe. However, the ME result indicates that about 5 at. % Fe atoms in FeIII (8 g) site of bct-Fe3B have been replaced by Nd atoms; the NMR result demonstrates that 11B NMR spectrum is the characteristic peak of bct-Fe3B, but it broadens asymmetrically to the high frequency side, which is due to the bct-Fe3B influenced by Nd atoms. The amplitude of radio frequency (rf) excitation field required to get the maximum 11B spin-echo signal from bct-Fe3B in the sample annealed at 839 °C is only about one third as much as that required to excite the 11B in the bct-Fe3B influenced by Nd atoms in the sample annealed at 670 °C for a short time, which implies the latter has a larger coercivity field than the former. It is concluded that the origin of hard magnetic properties of Nd4Fe77.5B18.5 alloy is not related to the 2:14:1 phase, but to the change of bct-Fe3B itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352404
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  • 4
    Electronic Resource
    Electronic Resource
    NMR study of the short range order in Fe–B amorphous powders prepared by borohydride reduction : 37th Annual conference on magnetism and magnetic materials (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 6983-6985 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Fe–B amorphous alloys powders with high boron concentration can be prepared by borohydride reduction (BHR). By adjusting technological factors, the Fe100−xBx amorphous powders with compositions ranging from x=17 to 40 can be easily obtained, but it is difficult to make the amorphous ribbons with such a high B concentration by using rapidly quenched technique, which can usually obtain the amorphous ribbons with the compositions ranging from x=12 to 25. Up to now, there are different points of view about if the short range order (SRO) in the Fe–B amorphous powders prepared by the BHR around room temperature is the same with that in the amorphous ribbons made by rapidly quenched and vapor depositing techniques. In this paper, the SRO in Fe100−xBx amorphous powders with various boron concentration prepared by the BHR have been studied by the zero field spin echo nuclear magnetic resonance (NMR) technique. It was shown that the types of SRO in these samples vary with the B concentration. There exist Fe3B- and Fe2B-like SRO and a small amount of α-Fe in the samples with lower B concentration, while there are Fe3B- and FeB-like SRO in the alloys with higher B concentration. Fe3B-like SRO, however, only exists in the amorphous ribbons obtained by rapidly quenched method. It can be concluded that there are different types of SRO in the amorphous alloys prepared by different methods. This conclusion can explain the reason why the average hyperfine field at Fe sites deceases with the B concentration increasing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352405
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  • 5
    Electronic Resource
    Electronic Resource
    Parallel conduction in GaAs heterostructures modified by low-energy ion exposure (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 647-650 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a systematic study of the low-temperature magnetotransport properties of modulation-doped GaAs heterostructures to examine the device isolation mechanism in a low-energy (150 eV) Ar+ ion exposure process. Measurements were carried out repeatedly on the same Hall bar as a function of the ion exposure time. A gradual evolution from parallel conduction to strictly single-channel conduction was observed. The carrier density of the upper channel was depleted by ion surface milling, while the lower channel two-dimensional electron gas was essentially unaffected. The data indicated that carrier depletion and the subsequent breakdown in electron screening of the long-range random potential was the main reason for device isolation during the low-energy ion exposure process, in agreement with recent theoretical work. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360807
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  • 6
    Electronic Resource
    Electronic Resource
    Large change of the giant magnetoresistance behavior after changing the spacer from Cu to CuMn alloy in Co/spacer/Co structures (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5030-5032 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The giant magnetoresistance (GMR) effects in sandwiched Co/Cu/Co and Co/CuMn/Co structures have been investigated. The GMR oscillates with the spacer thickness for both cases, but is nearly antiphased. With diluted Mn atoms in the Cu spacer, the GMR curve as a function of the magnetic field changes a lot, and the saturation/switching field for GMR can be reduced greatly compared with that in Co/Cu/Co systems. This may indicate one way to obtain a highly sensitive GMR. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370081
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  • 7
    Electronic Resource
    Electronic Resource
    Numerical study of argon ions transported across the sheath in electron cyclotron resonance discharges (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 1351-1357 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transport of argon ions through the sheath as well as through the neutral region in electron cyclotron resonance discharges in argon gas is studied by means of Monte Carlo simulation, with the emphasis on the sheath potential and the characteristics of argon ions in the sheath. The evolution of the energy, velocity, and angle distributions of the ions in the sheath and the dependence of the distributions on gas pressure and substrate bias are investigated primarily concerned with collisional sheath. It is found that the effect of the pressure on the ion behavior in the sheath is not the same as in the neutral region, however, the substrate bias greatly influences the ion behavior mainly due to ion-neutral elastic collisions within the sheath. Our results also show that the ion motion in crossing the sheath tends to be parallel to the applied magnetic field, and an ion flux with good directionality can be expected by imposing on a negative voltage substrate. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369266
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrasonic attenuation in Zr41Ti14Cu12.5Ni10−xBe22.5Cx (x=0,1) bulk metallic glasses under high pressure (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3266-3268 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The pressure dependence of ultrasonic attenuation in Zr41Ti14Cu12.5Ni10−xBe22.5Cx (x=0,1) bulk metallic glasses has been studied up to 0.5 GPa by using a pulse echo overlap method. The effect of carbon addition on the attenuation is also investigated. Some unique characteristics of the ultrasonic attenuation are found and compared with those of other glasses. The origin of the anomalous attenuation behavior is discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1289237
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  • 9
    Electronic Resource
    Electronic Resource
    The influence of electron-hole density profile on the picosecond time-resolved reflectivity measurement in silicon (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 5031-5034 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the spatial distribution of electron-hole plasma on reflectivity measurement is studied in this paper. The plasma density deduced from the reflectivity measurement represents the surface density satisfactorily, if the pump penetration depth is not too short compared with probe wavelength. Besides, when plasma resonance does not take place, the probe incident angle should not be close to Brewster's angle [see, for example, M. Born and E. Wolf, Principles of Optics, 6th ed. (Pergamon, New York, 1980), p. 43] for exponential-like plasma density distribution; otherwise, when the phasma resonance takes place, strong nonlinear recombination and diffusion should be present. In other cases, a general applicable method for data processing is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.343177
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  • 10
    Electronic Resource
    Electronic Resource
    Photoemission study of the effect of thermal annealing on Cs2O/Si(111) surfaces (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 3787-3791 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Cs2O overlayers with different thickness were prepared by simultaneous oxygen–cesium adsorption on Si(111) at room temperature. Photoelectron spectroscopy and work-function measurements have been used to study the Cs2O/Si surfaces as a function of annealing temperature. The results show that the interaction of the Cs2O overlayer with the substrate is weak. The Cs2O species is sensitive to x-ray radiation, forming a new species on the top surface. The Cs2O/Si surfaces exhibit a negative electron affinity with a work-function value of 0.85±0.1 eV until the Cs2O species decomposes completely. After Cs2O disappears, both Cs–O and Si–O bonds are dominant on the surfaces with a work function of about 1.2 eV. For further annealing, the oxygen bonded to cesium gradually transfers to Si due to Cs desorption. The thickness of the SiO2 overlayer formed after Cs desorption is dependent on the mount of oxygen in the Cs2O overlayer. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1405133
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