Publications by authors named "Riccardo Bassiri"

The mirror suspensions in gravitational wave detectors demand low mechanical loss jointing to ensure good enough detector performance and to enable the detection of gravitational waves. Hydroxide catalysis bonds have been used in the fused silica suspensions of the GEO600, Advanced LIGO, and Advanced Virgo detectors. Future detectors may use cryogenic cooling of the mirror suspensions and this leads to a potential change of mirror material and suspension design.

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Glasses are nonequilibrium solids with properties highly dependent on their method of preparation. In vapor-deposited molecular glasses, structural organization could be readily tuned with deposition rate and substrate temperature. Here, we show that the atomic arrangement of strong network-forming GeO glass is modified at medium range (<2 nm) through vapor deposition at elevated temperatures.

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The sensitivity of current and planned gravitational wave interferometric detectors is limited, in the most critical frequency region around 100 Hz, by a combination of quantum noise and thermal noise. The latter is dominated by Brownian noise: thermal motion originating from the elastic energy dissipation in the dielectric coatings used in the interferometer mirrors. The energy dissipation is a material property characterized by the mechanical loss angle.

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The energy landscape of ZrO-doped amorphous TaO is explored in this work. With models corresponding to experimental concentrations of 50% Zr and 50% Ta cations, we search for, gather, and analyze two-level systems (TLSs) from molecular dynamic simulations. The mechanical loss function is calculated for each TLS individually.

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Amorphous tantala () thin films were deposited by reactive ion beam sputtering with simultaneous low energy assist or /2+ bombardment. Under the conditions of the experiment, the as-deposited thin films are amorphous and stoichiometric. The refractive index and optical band gap of thin films remain unchanged by ion bombardment.

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We present the optical and structural characterization of films of , , and doped with a cation ratio around 0.1 grown by reactive sputtering. The addition of as a dopant induces the formation of tantalum suboxide due to the "oxygen getter" property of scandium.

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Amorphous films and coatings are rapidly growing in importance. Yet, there is a dearth of high-quality structural data on sub-micron films. Not understanding how these materials assemble at atomic scale limits fundamental insights needed to improve their performance.

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