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    دورية أكاديمية

    المصدر: Nanophotonics, Vol 13, Iss 9, Pp 1581-1592 (2024)

    الوصف: Hyperbolic phonon polaritons (HPhPs), hybrids of light and lattice vibrations in polar dielectric crystals, empower nanophotonic applications by enabling the confinement and manipulation of light at the nanoscale. Molybdenum trioxide (α-MoO3) is a naturally hyperbolic material, meaning that its dielectric function deterministically controls the directional propagation of in-plane HPhPs within its reststrahlen bands. Strategies such as substrate engineering, nano- and hetero-structuring, and isotopic enrichment are being developed to alter the intrinsic dielectric functions of natural hyperbolic materials and to control the confinement and propagation of HPhPs. Since isotopic disorder can limit phonon-based processes such as HPhPs, here we synthesize isotopically enriched 92MoO3 (92Mo: 99.93 %) and 100MoO3 (100Mo: 99.01 %) crystals to tune the properties and dispersion of HPhPs with respect to natural α-MoO3, which is composed of seven stable Mo isotopes. Real-space, near-field maps measured with the photothermal induced resonance (PTIR) technique enable comparisons of in-plane HPhPs in α-MoO3 and isotopically enriched analogs within a reststrahlen band (≈820 cm−1 to ≈972 cm−1). Results show that isotopic enrichment (e.g., 92MoO3 and 100MoO3) alters the dielectric function, shifting the HPhP dispersion (HPhP angular wavenumber × thickness vs. IR frequency) by ≈−7 % and ≈+9 %, respectively, and changes the HPhP group velocities by ≈±12 %, while the lifetimes (≈3 ps) in 92MoO3 were found to be slightly improved (≈20 %). The latter improvement is attributed to a decrease in isotopic disorder. Altogether, isotopic enrichment was found to offer fine control over the properties that determine the anisotropic in-plane propagation of HPhPs in α-MoO3, which is essential to its implementation in nanophotonic applications.

    وصف الملف: electronic resource

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    المساهمون: Schwartz, Barry

    المصدر: Holocaust Studies. 29,1 (2023) 116-140

    Subject Person: Wallenberg, Raoul 1912-1947

    الوصف: Many Historical events and persons have been forgotten for decades, centuries, even millennia before recovery. Until the 1980s, Raoul Wallenberg's efforts to rescue the Jews of Budapest from Nazi atrocities were rarely commemorated, even obscured, and largely forgotten, whether in Hungary, his home country of Sweden, or i9n Israel, where many of the people he rescued lived. This essay explores how political and social shifts enabled belated recognition of Wallenberg's deeds in Israel, primarily through the efforts of local agents working from below, with implications for understanding how historical memory is belatedly recovered more generally.

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    المساهمون: ראובן, פרץ

    المصدر: במעבה ההר; מחקרי הר אפרים ובנימין. 13,1 (2023) 65-86

    Subject Person: Joshua (Biblical figure)

    جغرافية الموضوع: Samaria (Region) (West Bank) -- Antiquities

    الوصف: This paper presents an Arabic inscription found on a table in the maqam attributed to Joshua son of Nun in the village of Kifl Haris in Samaria. The inscription, which was still located on site until the mid-20th century, provides a unique description of the phenomenon of “replacement pilgrimage”. This term denotes the act of pilgrimage to Mecca (Hajj) on behalf of a person who is unable to perform this commandment. The inscription describes a pilgrimage that took place in the early 13th century CE for one of the princes of the Ayyubid dynasty, Al-Malik al-Awhad, who governed in the Armenian region. The Hajj was carried out by a certain Jawhar, presumably a resident of the village. The central position of the table in the holy tomb testifies to the significance of the site and its popularity in the 13th century CE. This is also apparent from the account of a Jewish traveler who documented his visit to the site.

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