简介:Fivenovelnear-infraredelectrochromicaromaticpolyimides(PIs)withpendentbenzimidazolegroupweresynthesizedfrom4,4’-diamino-4’’-(1-benzylbenzimidazol-2-yl)triphenylamine(namedasDBBT)withfivedifferentdianhydridesviatwo-steppolymerizationprocess,respectively.ThemaximumUV-VisabsorptionbandsofthesePIslocateatabout335nmforsolidfilmsduetotheπ-π*transitions.Areversiblepairofdistinctredoxpeaks,thatwereassociatedwithanoticeablecolorchangefromoriginalyellowtoblue,wasobservedinthecyclicvoltammetry(CV)test.Anewabsorptionpeakemergedat847nminnear-infrared(NIR)regionwithincreasingvoltageinUV-Vis-NIRspectrum,whichindicatesthatPIcanbeusedasNIRelectrochromicmaterial.ThesenovelPIshavegoodelectrochemicalstability,appropriateenergylevelsforthehighestoccupiedmolecularorbital(HOMO)andthelowestunoccupiedmolecularorbital(LUMO),intherangeof-5.17eVto-5.20eVand-2.14eVto-2.26eV(versusthevacuumlevel)determinedbycyclicvoltammetrymethod.Thesevaluesbasicallyconsistedwiththeresultsofquantumchemicalcalculation.Thesepolyimidescanbeusedasnovelelectrochromicandholetransportationmaterials.
简介:摘要:本文运用Micaps常规资料、EC细网格模式资料分析了2020年8月15~17日出现在四川省青川县由于西太平洋副热带高压稳定维持而引发的连续性强降雨天气过程。结果表明:青川县处于500hPa副热带高压和川西高原东移小槽之间的“夹心饼”地带时,容易出现连续性强降雨天气;降雨过程中低空700hPa的南风气流和切变线与850hPa的倒槽切变有利于低层辐合,高空100hPa南亚高压东部脊线附近的分散型气流有利于高层辐散,低层的辐合配合高层的辐散,有利于大范围的上升运动;低层700hPa比湿达到13k/kg,850hPa比湿达到17k/kg是青川县降大暴雨的一个重要指标条件。