能级强关联结构与宽能域激发协同调控的高效光子上转换新机制

Aiming at the problems that rare earth ions (RE3+:(Er3+, Tm3+, Ho3+,Nd3+ etc. ) are of narrow excitation band，parity-of forbidden transitions within 4f n configuration, strong electron-phonon coupling (EPC), and difficult to photonic field electric polarization (PEP), concentration quenching and cross relaxation etc., which seriously restrict the efficiency of upconversion luminescence (UCL) of nanomaterials codoped with RE3+, we are going to adopt a novel strategy that the multiple pathways, to reduce parity-symmetry of RE3+ in nanoparticlas with single RE3+, to enhance correlation of energy levels of RE3+, to broaden excitation energy domain, to enhance the PEP and to control EPC, etc., are combined with constructing novel UCL nanomaterials with multi-sell/core nanostructure (SCNs) of NaEr(or Tm3+)F4 core@NaY(or Lu, or Gd)F4 shell@TiO2:Er3+(or Tm3+) shell@TiO2 shell, which is composed of a highly dielectric constant shell layer ,a lattice transition layer, and a NaErF4 core with low parity symmetry via lightly codoping of Li+ and K+ for enhancing efficiency of UCL. The research contents include: nanostructure particals with level strong correlation of Er3+(or Tm3+) to broad the red light excitation energy domain from 600 to 1700nm (multiple wavelengths), effects of regulation and controlling of structure of multi-functional shells consisting of a TiO2 semiconductor shell layer doped with heavy Er3+(or Tm3+), effects of cooperative modulation between excitation of near infrared multiple wavelengths with selective excitation and the SCNs structure on modulation of PEP and EPC in SCNs. Adopting a new strategy for cooperative regulation of functional nanostructures and wide energy range excitation combined with selective wavelength. Two key questions are expected to be answered with this project, i.e. the relationship between SCNs structure and strong correlation among RE3+ levels, and the dependence of the modulation of the cooperative co-excitation of the near infrared excitation of broad energy field and selected excitation on PEP and EPC in SCNs, to develop a highly efficient UCL nanomaterial with novel SCNs by adopting an innovative manipulating strategy of the nanostructure modulation and adaptive co-excitation of excitation and selected excitation in broad energy field for breaking through the scientific bottleneck of restricting UCL efficiency to develope a novel highly efficient UCL nanomaterial.

针对浓度猝灭和交叉弛豫、稀土离子(RE3+)激发带窄、4fn组态宇称禁戒跃迁、电极化(PEP)难、电-声耦合(EPC)强等制约RE3+上转换发光(UCL)效率问题，本项目提出降低RE3+宇称、加强能级间关联、扩宽激发能域、加强PEP和调控EPC多重策略相结合，构建Er3+(或Tm3+)低宇称核@同质壳@TiO2:Er3+@TiO2壳UCL纳米粒子(SCNs)。研究Er3+(或Tm3+)能级强关联核结构与宽能域多带激发的关系；TiO2多界面场和同质隔离壳层结构调控PEP强度和EPC；SCNs结构调控与宽能域激发和选择激发协同调控与PEP和EPC关系。采用纳米结构调控与宽能域多带激发协同调控方法，重点解决SCNs结构与Er3+(或Tm3+)间能级关联性关系，认识和理解能级强关联的SCNs纳米结构与抑制浓度猝灭、增强交叉弛豫、调控PEP和EPC关系两个关键科学问题，突破制约UCL效率的科学瓶颈。

稀土发光纳米材料在多领域具有广泛应用。然而，稀土离子浓度发光猝灭和交叉弛豫、离子激发带窄、电极化难、高浓度离子发光机理不清等问题制约了稀土离子上/下转换发光效率。此外，尽管有大量的稀土离子上/转换发光的生物医学应用，但是其在医学应用中光暗毒性和近红外成像波长无法突破1530nm等限制其成像清晰度和分辨率等性能提高。. 为解决上述问题，开了如下内容研究：. 1）设计和构建准100%Er3+(或Tm3+)核/ NaY(Lu和Gd)F4壳纳米粒子（MSNP）及其发光研究。. 2）MSNP结构调控与宽能域激发和选择激发调控及其发光机理研究。. 3）项目研究结果在肿瘤诊治及其近红外II-III区成像及其痕量水分子检测中的创新应用研究。. 4）新型近红外纳米光敏材料拓展及其应用研究。. 研究取得了如下重要结果：. 1) 应用100%Er3+(或Tm3+)基材料加强了离子能级强关联性，解决了离子吸收带窄、光场难极化等问题，通过结构和选择激发调控，建立了等能传递主导的物理模型，实现了上/下转换高效率。 . 2) 将结构和选择激发调控与温度调控相结合，应用理论模拟和光谱阐述了高Er3+体系交叉弛豫（CR）机制，实现了100%Er3+(或Tm3+)单一体系更高UCL效率;通过温控抑制多声子协助CR，550nm的上转换强度增强2000倍。. 3）发展了肿瘤pH敏感分子开关层包覆上转换和光敏剂复合球方法，解决了其治疗产生光暗毒性难题。. 4）将Er3+能级强关联与Tm3+能量调控相结合，提高了1530nm荧光效率、成像更清晰；首次突破目前近红外II区1600nm成像波长局限,实现了1800 nm近红外荧光成像探针。. 5）项目执行期间，发表SCI论文12篇，其中，影响因子大于10文章5篇。此外，一篇已被Nature Comms正式接收，另一篇JACS正在修改中。获吉林省自然科学二等奖1项，5项发明专利正在申请中（见附件专利申请通知书）。培养毕业1名博士，4名在读博士研究生。. 上述结果对稀土发光纳米探针在多领域应用起到了促进和引领作用。

内容获取失败，请点击重试