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In diesem Paper wird ein innovatives Konzept zur Herstellung von hochempfindlichen ungekühlten Mikrobolometern, zur Detektion von langwelliger Infrarotstrahlung (IR-Strahlung) in einem Wellenlängenbereich von 8 μm-14 μm, beschrieben. Der Ansatz basiert auf der Realisierung der thermischen Isolierung und gleichzeitiger elektrischer Kontaktierung der Mikrobolometer mit Hilfe von ausreichend langen und dünnbeschichteten Hohlröhrchen (hier als Nanotubes bezeichnet), welche mit Technologien und Prozessen aus der Mikrosystemtechnik hergestellt werden können. Somit wird der relative Flächenanteil des Absorbers bei einer gegebenen Pixelgröße maximiert, da laterale Stege, welche bislang Hauptbestandteil der thermischen Isolierung waren, komplett entfallen. Der resultierende thermische Leitwert kann über die einzelnen Schichtdicken, Grundradius und Länge der Nanotubes flexibel und unabhängig von der Pixelgröße eingestellt werden. Die gefertigten Nanotube-Mikrobolometer werden zunächst anhand von Teststrukturen im Hinblick auf die elektro-optischen und mechanischen Eigenschaften grundlegend charakterisiert. Der Fokus liegt in dieser Arbeit auf Pixelgrößen von 12 μm. A novel structure for realization of thermal isolation and electrical contacting of microbolometers is described in this paper. This structure is formed by thin coated hollow tubes (termed as nanotubes in this work), which can be fabricated by processes of microsystems technology. Therefore, commonly used lateral legs as main component of thermal isolation can be excluded in order that the effective absorption area is maximized. The resulting thermal conductance can be tuned independently from the pixel size by varying layer thicknesses, base radius and length of the structured nanotubes. The fabricated 12 μm pixel size nanotube microbolometers are characterized with respect to electrical-optical and mechanical properties by means of test structures. [ABSTRACT FROM AUTHOR]

We used ultrafast electron diffraction and density-functional theory calculations to gain insight into the charge density wave (CDW) formation on In/Si(lll). Weak excitation by a femtosecond-laser pulse results in the melting of the CDW. The immediate freezing is hindered by a barrier for the motion of atoms during the phase transition: The melted CDW constitutes a long-lived, supercooled phase and is strong evidence for a first-order transition. The freezing into the CDW is triggered by preexisting adsorbates. Starting at these condensation nuclei, the CDW expands one dimensionally on the In/Si(l 11) surface, with a constant velocity of more than 80 m/s. [ABSTRACT FROM AUTHOR]

The dynamics of vibrations localized in a monolayer of Pb on Si( 111) is studied using density functional theory and molecular dynamics methods. Recently, a pump-probe experiment has given direct access to the relaxation dynamics of the vibrational excitations in Pb, revealing two distinct time scales which are separately related to the directions of the Pb vibrational motions [Ultramicroscopy 127, 2 (2013)]. We analyze the experimental findings theoretically using atomistic modeling. After excitation of two-dimensional optical phonons, equilibration between parallel and perpendicular modes is observed before dissipation into the Si substrate. Even after several nanoseconds, equilibration with the substrate is not achieved due to energy trapped in acoustic Pb modes. [ABSTRACT FROM AUTHOR]

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are concerning in the ongoing coronavirus disease 2019 (COVID-19) pandemic. Here, we developed a rapid test, termed CoVariant-SCAN, that detects neutralizing antibodies (nAbs) capable of blocking interactions between the angiotensin-converting enzyme 2 receptor and the spike protein of wild-type (WT) SARS-CoV-2 and three other variants: B.1.1.7, B.1.351, and P.1. Using CoVariant-SCAN, we assessed neutralization/blocking of monoclonal antibodies and plasma from COVID-19–positive and vaccinated individuals. For several monoclonal antibodies and most plasma samples, neutralization against B.1.351 and P.1 variants is diminished relative to WT, while B.1.1.7 is largely cross-neutralized. We also showed that we can rapidly adapt the platform to detect nAbs against an additional variant—B.1.617.2 (Delta)—without reengineering or reoptimizing the assay. Results using CoVariant-SCAN are consistent with live virus neutralization assays and demonstrate that this easy-to-deploy test could be used to rapidly assess nAb response against multiple SARS-CoV-2 variants.