Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials ...Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials like metasurfaces,undistorted transmission usually requires each meta-atom to possess exactly the same transmission amplitude and phase.Here,we consider a special acoustic metasurface consisting of meta-atoms with the same transmission phase but different transmittance.Interestingly,we find that when the meta-atoms are of subwavelength scale,the difference in transmittance would not induce substantial distortion in the transmitted wavefront.Based on this observation,we numerically and experimentally demonstrate acoustic metasurfaces that exhibit undistorted transmission and configurable arbitrary reflection.Two distinct types of reflection,i.e.,anomalous reflection and diffuse reflection,are numerically and experimentally demonstrated with the transmission wavefront undistorted through a broad spectrum.Our work reveals a more general condition for realizing broadband undistorted transmission and configurable reflection with metasurfaces,which has potential implications in acoustic field manipulation and novel sonar domes.展开更多
Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded forma...Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0211400)the National Natural Science Foundation of China(Grants Nos.12474293,12174188,12404364,12504545,12504515,and 12174192)+2 种基金the State Key Program of National Natural Science Foundation of China(Grant No.11834008)the Natural Science Foundation of Jiangsu Province(Grants Nos.BK20240575 and BK20233001)the China Postdoctoral Science Foundation(Grants No.2023M731612)。
文摘Broadband undistorted transmission is one of the criteria to preserve the information carried by incident waves and pulses,allowing imaging formation and source detection.For transmission through artificial materials like metasurfaces,undistorted transmission usually requires each meta-atom to possess exactly the same transmission amplitude and phase.Here,we consider a special acoustic metasurface consisting of meta-atoms with the same transmission phase but different transmittance.Interestingly,we find that when the meta-atoms are of subwavelength scale,the difference in transmittance would not induce substantial distortion in the transmitted wavefront.Based on this observation,we numerically and experimentally demonstrate acoustic metasurfaces that exhibit undistorted transmission and configurable arbitrary reflection.Two distinct types of reflection,i.e.,anomalous reflection and diffuse reflection,are numerically and experimentally demonstrated with the transmission wavefront undistorted through a broad spectrum.Our work reveals a more general condition for realizing broadband undistorted transmission and configurable reflection with metasurfaces,which has potential implications in acoustic field manipulation and novel sonar domes.
文摘Formic acid （HCOOH） decomposition at Pt film electrode has been studied by electrochem- ical in situ FTIR spectroscopy under attenuated-total-reflection configuration, in order to clarify whether bridge-bonded formate （HCOOD） is the reactive intermediate for COad for-mation from HCOOH molecules. When switching from HCOOH-free solution to HCOOH- containing solution at constant potential （E=0.4 V vs. RHE）, we found that immediately upon solution switch COad formation rate is the highest, while surface coverage of formate is zero, then after COad formation rate decreases, while formate coverage reaches a steady state coverage quickly within ca. 1 s. Potential step experiment from E=0.75 V to 0.35 V, reveals that formate band intensity drops immediately right after the potential step, while the COad signal develops slowly with time. Both facts indicate that formate is not the reactive intermediate for formic acid dehydration to CO.
