Abstract:The Perseverance rover landed in Jezero crater， Mars in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals instrument to perform deep ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks， probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks， preserved in minerals related to both aqueous environments.
编译 | 李言Science, 18 AUG 2023, Volume 381 Issue 6659《科学》2023年8月18日，第381卷，6659期生物物理学BiophysicsAlcanivorax borkumensis biofilms enhance oil degr
Abstract:Semiconducting cubic boron arsenide has been predicted to have carrier mobility of 1400 square centimeters per volt-second for electrons and 2100 square centimeters per volt-second for holes at room temperature. Using pump-probe transient reflectivity microscopy， we monitored the diffusion of photoexcited carriers in single-crystal c-BAs to obtain their mobility. With near-bandgap 600-nanometer pump pulses， we found a high ambipolar mobility of 1550 ± 120 square centimeters per volt-second， in good agreement with theoretical prediction. Additional experiments with 400-nanometer pumps on the same spot revealed a mobility of >3000 square centimeters per volt-second， which we attribute to hot electrons. The observation of high carrier mobility， in conjunction with high thermal conductivity， enables an enormous number of device applications for c-BAs in high-performance electronics and optoelectronics.
