Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 1661-1669 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A detailed analysis of the photocapacitance signal at the near-band and extrinsic energetic ranges in Schottky barriers obtained on horizontal Bridgman GaAs wafers, which were implanted with boron at different doses and annealed at several temperatures, has been carried out by using the optical isothermal transient spectroscopy, OITS. The optical cross sections have been determined as well as the quenching efficiency of the EL2 level which has been found to be independent of the annealing temperature. Moreover, the quenching relaxation presents two significant features: (i) a strong increase of the quenching efficiency from 1.35 eV on and (ii) a diminution of the quenching transient amplitude in relation with that shown by the fundamental EL2 level. In order to explain this behavior, different cases are discussed assuming the presence of several energy levels, the existence of an optical recuperation, or the association of the EL2 trap with two levels located, respectively, at Ev+0.45 eV and Ec−0.75 eV. The theoretical simulation, taking into account these two last cases, is in agreement with the experimental photocapacitance data at low temperature, as well as at room temperature where the EL2 filling phototransient shows an anomalous behavior. Moreover, unlike the previous data reported for the EL2 electron optical cross section, the values found using our experimental technique are in agreement with the behavior deduced from the theoretical calculation. The utilization of the OITS method has also allowed the determination of another level, whose faster optical contribution is often added to that of the EL2 level when the DLOS or standard photocapacitance is used.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 1886-1888 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Measurements of single-photon photoelectric emission sensitivity of ion implanted polycrystalline tungsten surface by 3×1016 K+ ions/cm2 are reported. They are compared to the data previously obtained for pure tungsten tested under the same conditions. The enhancement of the photoelectric sensitivity up to a factor of 50 was measured as a consequence of the change in the electronic properties of the tungsten surface, induced by the implanted alkali metal ions. Compared with other techniques used to reduce the work function of pure tungsten, the implanted surface exhibits a lower work function than the pure metal, and is capable of supporting high laser intensity for a long time. For these reasons it seems possible to consider the ion-implantation technique as a suitable new method to significantly improve the photoelectric performances of usual metals, under high laser intensity illuminations. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Copenhagen : Blackwell Publishing Ltd
    Contact dermatitis 44 (2001), S. 0 
    ISSN: 1600-0536
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 8574-8585 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study PdPt bimetallic clusters in both free and supported phases. These clusters have been produced with a laser vaporization source. Free clusters directly produced by the source are studied by time of flight mass spectrometry and photofragmentation technique. We observed a sequential evaporation of Pd atoms in the mixed clusters consistent with a palladium segregation process. This tendency has been also observed on supported particles from which the structure and the composition are determined by high resolution transmission electron microscopy and energy dispersive x-ray analysis. A main result is that each particle has the composition of the massic rod vaporized in the source. The supported particles are well crystallized and exhibit truncated octahedron shapes. Experimental observations are well explained using a modified tight binding model. Indeed, within this model, we found that the equilibrium shape is strongly related to the variation of the cohesive energy with atomic coordination number. Also, some preliminary results on the specific reactivity of these bimetallic clusters are presented. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Among the most important crops in developing countries are banana and plantain. However, the production is threatened by increasingly virulent forms of Fusarium wilt, and therefore, intensive breeding programmes are being carried out worldwide. As conventional field studies of banana resistance to this disease are time-consuming and destructive, an easy-to-do procedure was previously developed to differentiate field-grown resistant and susceptible banana cultivars at leaf level. Such a procedure involved the in vitro treatment of fungal culture filtrates on to field-grown adult leaves and the measurement of lesion areas 48 h later. The present report includes measurements of other indicators such as biochemical compounds. The cultivar ‘Gross Michel’ (susceptible) and cv. ‘FHIA-01’ (resistant) leaves were treated with Fusarium oxysporum f. sp. cubense race 1 culture filtrates. Evaluations were performed 48 h after leaf treatment. Compared with culture medium-treated leaves (control treatment), fungal metabolites produced leaf lesions, decreased freephenolic contents and increased protein levels in both cultivars. In ‘FHIA-01’, the culture filtrate increased contents of cell wall-linked phenolics and the pool of aldehydes (except malondialdehyde). Fungal metabolites did not cause variations in peroxidase activity, chlorophyll pigment contents or malondialdehyde level in any cultivar. The use of Fisher's linear discriminant analysis to differentiate resistant and susceptible banana cultivars in breeding programmes is also a novel aspect of this report. Such an estimation was performed from a data matrix that included the effects of the fungal metabolites (leaf lesion area and levels of free and cell wall-linked phenolics, aldehydes, except malondialdehyde, and proteins) on banana leaves of seven cultivars (four susceptible and three resistant).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 52 (1990), S. 345-361 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 4607-4613 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Distributions of neutral Si-clusters centered around mean sizes of 50 and 200 atoms have been produced using a laser vaporization source and deposited on various substrates at room temperature in ultrahigh vacuum. The Si-cluster assembled films obtained, resulting from the random stacking of incident free nanosize clusters, were subsequently coated by appropriate protective layers before removing in air to perform ex situ infrared, visible, Raman, and photoluminescence spectrometry measurements, as well as transmission electron microscopy observations. The main characteristics of the cluster films are comparable to those observed for amorphous hydrogenated silicon and quite different to those of conventional nanoporous structures or clusters larger than 2–3 nm. The observed intense photoluminescence signal and band gap suggest the presence of a low number of dangling bonds probably due to surface reconstruction effects, connections between adjacent clusters, and oxygen contamination. As for the oxygen contamination, infrared and x-ray photoemission spectrometry measurements agree with the assumption of oxygen atoms trapped at the cluster surface. Finally, all the results on the vibrational and optical properties tend to confirm the failure of the classical confinement model in a diamond lattice to explain the behavior of such nanostructured materials with grain size typically in the nanometer range. The presence of five-membered rings characteristic of the Si-cluster structures in this size range with the subsequent rehybridization effects, as well as the connection process between adjacent clusters seem to be a track which is discussed for a better interpretation of the results. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 10278-10287 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nanosize neutral silicon clusters produced using a laser vaporization source were analyzed in the gas phase and deposited on various substrates at room temperature in ultrahigh vacuum. Nanostructured thin films with thickness around 100 nm resulting from this nearly ballistic deposition process were subsequently characterized by several complementary electron spectroscopy techniques to investigate the electronic structure. The film properties are comparable to those of a disordered phase but different from the properties of conventional amorphous or nanoporous silicon. The specific features observed in the Si-cluster assembled films cannot be simply interpreted on the basis of quantum confinement effects and are rather attributed to the presence of odd-membered rings in the incident-free cluster structure. Some Si-cluster geometries in the subnanometric size range are proposed and discussed on the basis of the experimental results and a tight binding scheme. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 106 (1984), S. 7643-7644 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 6309-6314 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have measured the electron optical capture cross section, σ0n(hν), of EL2 (the most important native center in GaAs) using a new technique which we have recently developed: optical admittance spectroscopy. This is a spectroscopic technique based on the measurement of the capacitance and conductance of a junction under monochromatic light of energy hν. This technique allows the measurement of the spectrum σ0n(hν) of each center located in the band gap. We have measured the electron photoionization cross section of the EL2 center, σ0n(hν), at three different temperatures within a range limited at high temperature by thermal emission and at low temperature by photoquenching (a feature characteristic of EL2 below 140 K). The study of the experimental data reveals that this center has a more complex nature than that of a simple defect. It seems to behave like a family of very close levels corresponding to similar atomic structures and located near the midgap. These results also reveal the existence of a shallow level close to the valence band and associated with EL2.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...