Sandoval Perla J, Lopez Karen, Arreola Andres, Len Anida, Basravi Nedah, Yamaguchi Pomaikaimaikalani, Kawamura Rina, Stokes Camron X, Melendrez Cynthia, Simpson Davida, Lee Sang-Jun, Titus Charles James, Altoe Virginia, Sainio Sami, Nordlund Dennis, Irwin Kent, Wolcott Abraham
Department of Chemistry, San José State University, 1 Washington Square, San José, California 95192, United States.
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sandhill Road, Menlo Park, California 94025, United States.
ACS Nanosci Au. 2023 Sep 15;3(6):462-474. doi: 10.1021/acsnanoscienceau.3c00033. eCollection 2023 Dec 20.
Surface chemistry of materials that host quantum bits such as diamond is an important avenue of exploration as quantum computation and quantum sensing platforms mature. Interfacing diamond in general and nanoscale diamond (ND) in particular with silica is a potential route to integrate room temperature quantum bits into photonic devices, fiber optics, cells, or tissues with flexible functionalization chemistry. While silica growth on ND cores has been used successfully for quantum sensing and biolabeling, the surface mechanism to initiate growth was unknown. This report describes the surface chemistry responsible for silica bond formation on diamond and uses X-ray absorption spectroscopy (XAS) to probe the diamond surface chemistry and its electronic structure with increasing silica thickness. A modified Stöber (Cigler) method was used to synthesize 2-35 nm thick shells of SiO onto carboxylic acid-rich ND cores. The diamond morphology, surface, and electronic structure were characterized by overlapping techniques including electron microscopy. Importantly, we discovered that SiO growth on carboxylated NDs eliminates the presence of carboxylic acids and that basic ethanolic solutions convert the ND surface to an alcohol-rich surface prior to silica growth. The data supports a mechanism that alcohols on the ND surface generate silyl-ether (ND-O-Si-(OH)) bonds due to rehydroxylation by ammonium hydroxide in ethanol. The suppression of the diamond electronic structure as a function of SiO thickness was observed for the first time, and a maximum probing depth of ∼14 nm was calculated. XAS spectra based on the Auger electron escape depth was modeled using the NIST database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to support our experimental results. Additionally, resonant inelastic X-ray scattering (RIXS) maps produced by the transition edge sensor reinforces the chemical analysis provided by XAS. Researchers using diamond or high-pressure high temperature (HPHT) NDs and other exotic materials (e.g., silicon carbide or cubic-boron nitride) for quantum sensing applications may exploit these results to design new layered or core-shell quantum sensors by forming covalent bonds via surface alcohol groups.
随着量子计算和量子传感平台的成熟，作为量子比特载体的材料（如金刚石）的表面化学是一个重要的探索方向。一般而言，将金刚石尤其是纳米级金刚石（ND）与二氧化硅连接起来，是将室温量子比特集成到光子器件、光纤、细胞或组织中并具备灵活功能化化学性质的一条潜在途径。虽然在ND核上生长二氧化硅已成功用于量子传感和生物标记，但启动生长的表面机制尚不清楚。本报告描述了负责在金刚石上形成二氧化硅键的表面化学，并使用X射线吸收光谱（XAS）来探测随着二氧化硅厚度增加时金刚石的表面化学及其电子结构。采用改良的施托伯（西格勒）方法在富含羧酸的ND核上合成了2 - 35纳米厚的SiO壳层。通过包括电子显微镜在内的多种重叠技术对金刚石的形态、表面和电子结构进行了表征。重要的是，我们发现羧化NDs上的SiO生长消除了羧酸的存在，并且碱性乙醇溶液在二氧化硅生长之前将ND表面转化为富含醇的表面。数据支持了一种机制，即ND表面的醇由于乙醇中的氢氧化铵再羟基化而生成甲硅烷基醚（ND - O - Si - (OH)）键。首次观察到金刚石电子结构随SiO厚度的变化，并且计算出最大探测深度约为14纳米。基于俄歇电子逃逸深度的XAS光谱使用美国国家标准与技术研究院（NIST）的表面分析电子能谱模拟数据库（SESSA）进行建模，以支持我们的实验结果。此外，由过渡边缘传感器产生的共振非弹性X射线散射（RIXS）图谱强化了XAS提供的化学分析。使用金刚石或高压高温（HPHT）NDs以及其他特殊材料（如碳化硅或立方氮化硼）进行量子传感应用的研究人员可以利用这些结果，通过表面醇基团形成共价键来设计新型分层或核壳量子传感器。
