Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Evidence of the influence of phonon density on Tm3+ upconversion luminescence in tellurite and germanate glasses (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 1871-1874 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Spectral properties of blue upconversion luminescences in Tm3+ doped tellurite (PWT, PbF2-WO3-TeO2) glasses and germanate (PWG, PbF2-WO3-GeO2) glasses pumped by a tunable dye laser were studied at room temperature. Two emission bands centered at 453 and 477 nm, corresponding to the 1D2→3H4 and 1G4→3H6 transitions of Tm3+ ions respectively, were observed. The two-photon absorption mechanism responsible for the 477 nm luminescence was confirmed by a quadratic dependence of luminescent intensities on the excitation power. Tellurite glasses showed a weaker upconversion luminescence than germanate glasses. This observation was inconsistent with the prediction from the phonon sideband measurement. In this article, Raman spectroscopy and transmittance measurement were employed to investigate the origin of the difference in upconversion luminescences in the two glasses. Compared with phonon sideband spectroscopy, Raman spectroscopy extracts more information, including both phonon energy and phonon density, and therefore, is a more effective analytical tool for understanding upconversion luminescence. Our results showed that the phonon energy as well as phonon density of the host glass is important in determining the upconversion efficiency. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1429762
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Spectroellipsometric study of sol–gel derived potassium sodium strontium barium niobate films (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 4491-4496 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Spectroscopic ellipsometry (SE) was used to characterize the sol–gel derived (K0.5Na0.5)0.4(Sr0.6Ba0.4)0.8Nb2O6 (KNSBN) thin films as a function of sol concentration. In the analysis of the measured SE spectra, a modified double-layer Forouhi–Bloomer model was adopted to represent the optical properties of the KNSBN films. In this model, the films were assumed to consist of two layers—a bottom bulk KNSBN layer and a surface layer that composed of bulk KNSBN as well as void. Good agreement was obtained between the measured spectra and the model calculations in the chosen spectral region. Effective medium approximation theory was used to evaluate the effective refractive index for the surface layer. The results of SE have been correlated with atomic force microscopy measurements of surface roughness. Our analyses have shown that the surface layer had a lower refractive index than the bottom one. In addition, the refractive index and the surface roughness of the KNSBN films increase with the sol concentration. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1355283
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Clinicopathological features and prognostic factors of cutaneous melanoma among Hong Kong Chinese (2004)
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 29 (2004), S. 0 
    Details
    ISSN: 1365-2230
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Cutaneous melanoma is rare among Chinese people. The clinicopathologic features and prognostic factors of 63 Hong Kong ethnic Chinese cases were analysed. We found that the mean age of onset was 65.5 years with a female : male ratio of 1 : 1.33. Forty-two (66.7%) patients had their tumours on their feet. More than 50% had the acral lentiginous histologic subtype. The mean tumour thickness was 5.73 mm with 92.1% (n = 58) having a Clark's level of III or more. Of the tumours, 57.1% were ulcerated. Stage I and II tumours comprised 73% (n = 46) while stage III and IV tumours made up of 26% (n = 17). The 1-, 3- and 5-year survival rates were 75%, 30% and 17%, respectively. Univariate analysis for overall survival showed that advanced clinical staging (stage III and IV), tumour ulceration and thicker tumour (〉4 mm) had a significantly poorer prognosis. Multivariate analysis demonstrated that advanced clinical staging was the most decisive prognostic factor followed by tumour ulceration. Our study showed that cutaneous melanoma in Chinese people is a disease predominantly of an older age group with the acral lentiginous histologic type located mainly on the feet. The prognosis depends on clinical staging and ulceration status.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-2230.2004.01644.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Pulsed CO2 laser ablation of graphite and polymers (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 2286-2290 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Spectroscopic analysis of the emission plumes of graphite, polyimide, polyethylene terepthalate, and polymethylmethacrylate that have been ablated by using a pulsed CO2 laser operating at 10.6 μm shows the presence of CN and C2, species not previously reported for CO2 laser ablation. The gross dynamics of the luminous plume, which was studied by using a streak camera, compares favorably with predictions from the snowplow model, which also accurately forecasts the time history of the plume expansion for a wide range of background gas pressures and laser fluences. Framing shadowgraphy reveals the onset of laser-supported detonation waves at approximately 50 mbar Ar, thus somewhat limiting the validity of this model. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.366970
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Effect of annealing in reduced oxygen pressure on the electrical transport properties of epitaxial thin film and bulk (La1−xNdx)0.7Sr0.3MnO3 (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3006-3010 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A comparative study of the effect of annealing in reduced oxygen pressure on the electrical transport properties of (La1−xNdx)0.7Sr0.3MnO3 (x=0, 0.25, 0.5, 0.75, and 1) epitaxial thin films and bulk materials has been carried out. The epitaxial films grown by pulsed laser ablation were in situ annealed in an oxygen atmosphere of 2×10−6–760 Torr at 700 °C for 1 h. It is found that the electrical transport behavior of the epitaxial film is insensitive to the annealing pressure. A similar thermal treatment on the bulk materials at 5 mTorr oxygen ambient, however, caused a dramatic change in their resistivity-temperature dependence. Our results suggest that the annealing has a prominent effect on the properties of grain boundary, which plays an important role in determining the electrical transport behavior of polycrystalline manganites. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.372291
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Intrinsic resputtering in pulsed-laser deposition of lead-zirconate-titanate thin films (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 245-247 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Pulsed-laser deposition (PLD) of lead-zirconate-titanate [Pb(Zrx,Ti1−x)O3] (PZT) thin films under low ambient pressure has been investigated by studying the angular deposition distributions of the constituent elements of the films. Nonstoichiometric profiles are observed and a dip occurs near the target surface normal of the deposition profile of lead. Experimental results show that intrinsic resputtering of the film is important in the PLD process and is responsible for the anomalous distribution of lead. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.113560
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    The role of ambient gas scattering effect and lead oxide formation in pulsed laser deposition of lead–zirconate–titanate thin films (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 2030-2032 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The angular distribution of lead in films deposited by pulsed laser irradiation of lead–zirconate–titanate and lead targets are studied as a function of ambient gas (argon or oxygen), gas pressure, and substrate temperature. When the substrate is kept in vacuum and at room temperature, a dip in the lead content attributable to the intrinsic resputtering of lead is observed at the position of the target surface normal. In the presence of an ambient gas, the dip disappears and the lead content increases at all angles. These results are attributed to a reduction of resputtering arising from scattering of the ablated species by ambient gas molecules. Under ambient oxygen and at high substrate temperature, the retention of lead content in the deposited films is largely due to the formation of lead oxide. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.116869
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Photoluminescence of transparent strontium–barium–niobate-doped silica nanocomposites (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4310-4312 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Optically transparent nanocomposites of strontium–barium–niobate (SBN) and silica were fabricated via a novel sol–gel method. The nanocomposites were annealed in temperatures of 600–800 °C to yield the nanometer-sized tetragonal tungsten–bronze phase of SBN crystallites. Photoluminescence studies at temperatures from 10 K to room temperature were performed. The undoped silica matrix showed a strong emission band at 3.2 eV and a weak emission band at 2.65 eV. They were noticeably suppressed in our SBN/SiO2 nanocomposites. Extra sharp peaks on top of the 3.2 eV band were seen. An additional emission band at 2.3 eV due to transitions within the NbO6 complex of SBN crystallites was also observed. This emission band showed a large blueshift with decreasing SBN crystallite size. This demonstrates that the photoluminescence spectra of ferroelectric-doped silica nanocomposites have a strong dependence on crystallite size. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1427419
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Binding of cyclic polyethers to ion pairs of carbanion alkali salts (1970)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 92 (1970), S. 666-670 
    Details
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ja00706a039
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Complexation of lithium, sodium, and potassium carbanion pairs with polyglycol dimethyl ethers (glymes). Effect of chain length and temperature (1970)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 92 (1970), S. 1955-1963 
    Details
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1021/ja00710a029
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...