Influence of the ice structure on the soft UV photochemistry of PAHs embedded in solid water

The UV photoreactivity of polycyclic aromatic hydrocarbons (PAHs) in porous amorphous solid water has long been known to form both oxygenated photoproducts and photofragments. The aim of this study was to examine the influence of the ice structure upon reactivity under soft UV irradiation conditions. Mixtures of PAHs with amorphous solid water (porous and compact) and crystalline (cubic and hexagonal) ices were prepared in a high vacuum chamber and irradiated using a mercury lamp for up to 2.5 hours. The results show that the production of oxygenated PAHs is efficient only in amorphous water ice, while fragmentation can occur in both amorphous and crystalline ices. We conclude that the reactivity is driven by PAH-water interactions in favourable geometries, notably where dangling bonds are available at the surface of pores. These results suggest that the formation of oxygenated PAH molecules is most likely to occur in interstellar environments with porous (or compact) amorphous solid water and that this reactivity could considerably influence the inventory of aromatics in meteorites.Comment: Accepted for publication in A&

A Single Smart Cut POI Substrate Design for UHF, L and S Band Filters

International audienceThe competition for the development of radio-frequency filters is still increasing with the imminence of the new telecommunication standard commercialization. Although investigated for years without real commercial breakthrough, the combination of piezoelectric films on Silicon is now receiving a very strong interest. In this contribution, we present the capability of Smart-Cut Piezo-On-Insulator (POI) substrates combining Lithium Tantalate and Silicon developed by SOITEC for the design and manufacturing of SAW filters. We particularly focus on one typical POI structure and we demonstrate its use for the design and fabrication of various filters taking advantage of the high performance modes enabled by the thin film perfect crystal structure on a frequency range starting from 400 MHz to 2.5 GHz and even more without changing the material stack