| Ion beam technology is one of the most important surface modification methods and surface analysis methods in material science research. In the past few decades, in information industry, healthy and medical industry, semiconductor industry and so forth, many key technologies have been developed according to the principle of ion beam technology. In terms of material-surface modification, the function of the ion irradiation is based on the interaction between energetic ion and the atoms in the materials, since this process is physical one, there are many benefits such as good controllability of the energy and dose of the irradiated ions, low requirement for the property of the modified materials, the adjustable experimental temperature, and the high directional property. It has been applied in lots of application field such as surface doping, ion beam etching or reduction or polishing, ion beam deposition, and optical waveguide formation. Meanwhile in surface analysis field, by using energetic ions produced by accelerating field to bombard the surface of materials, the energy can be transferred from energetic ions to the atoms in materials, which will cause the secondary radiation from the surface of the materials such as X-ray, y-ray, and secondary particles. Because these secondary radiations carry the information from the emission source, the information of the material's surface, such as material composition and concentration with depth distribution, can be analyzed by collecting the signal of the secondary radiation. At the same time, we could also test the lattice damage accumulation with depth based on the channeling effect. Based on all these principles many powerful tools were built for the surface analysis, such as Rutherford Backscattering Spectrometry/channeling spectra, particle induced X-ray emission, accelerator-based mass spectroscopic analysis, nuclear reaction analysis, secondary ion mass spectrometry, and so on.Based on the background above, the surface modification and surface analysis were carried out separately in our research. Our work can be divided into two aspects: (i) surface modification:we use ion irradiation to form ID optical waveguide on several popular optical crystals, study the optical property of the waveguides in visible and infrared band, and the lattice damage before and after irradiation; we also formed 2D ridge waveguide by combining ion irradiation and precise dicing.(?) surface analysis:we redesigned the "System for Analysis at the Liquid Vacuum Interface (SALVI)" system and combined SALVI and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) (we named it "in situ liquid SIMS") to determine the molecular structural evolution at the Solid Electrolyte Interphase (SEI) in Lithium-ion batteries; we also optimized the beam condition for in situ liquid SIMS to improve the molecular ion signal intensity, therefor molecular ion signal intensity has become very acceptable to use for in situ liquid SIMS to study solid-liquid and liquid-vacuum interfaces. The background and the work we did are as follow:1. As signal propagation channels and equipments connecting some devices with others, optical waveguide is the basis of the devices in integrated optics. Based on the principle of total reflection, optical waveguide structure could confine the light propagation in small volume with the dimensions of micrometer, which can increase the optical density, enhance many optical performances in the waveguide structures, and eventually contribute to the miniaturization and integration of the optical devices. Integrated optical circuit plays a more and more important role in modern electrommunication, sensor and detector, healthy and medical, and military field. Meanwhile, in research field, people pay more attentions in the laser effect, frequency doubling, optical parametric oscillator, and optical soliton.LGS is an abbreviation for Lanthanum gallium silicate (La3Ga5SiO14), which is an excellent carrier of the rare-earth ions. The sample was irradiated by using 330 MeV Kr8+ ions. And a 1D waveguide has been formed which could be used in infrared band. Using confocal micro-Raman spectra, we assessed the structural changes along the ion track and the lattice disorder distribution at the surface of the LGS crystal. The optical properties of the waveguide were researched in infrared band (1539 nm). KTP (potassium titanyl phosphate) has been widely used in various types of important integrated optic fields. Using proton irradiation, we fabricated a planar waveguide in a z-cut KTP crystal. According to experiment results, a single-mode infrared waveguide structure was formed which has protential value of application. Lithium niobate (LiNbO3) crystals are widely used in optical communications, optical data storage, and many laser technologies. We have reported a ridge waveguide structure prepared on a z-cut LiNbO3 crystal wafer using a combined ion irradiation and precise dicing process. The optical properties and propagation loss of the waveguide structure were researched after the annealing treatment.The further study will be focused on preforming some practical application based on the the planar and ridge waveguides formed by ion irradiation.2. With the development of mobile devices, the demand of the battery with high energy intensity is increasing sharply. As one of the anode materials with high specific mass energy, lithium metal always attracts people's sight. According to thermodynamics, lithium metal is very active, and it cannot be stable in an electrolyte, because reactions will happen when you put lithium metal into an electrolyte. However in reality, lithium metal could be very stable in a certain number of electrolytes due to a protective layer which is formed from the reactions between lithium metal and the electrolyte. This layer is named as Solid-Electrolyte Interphase (SEI). Molecularly, the surface of liquid or the interface between liquid and solid (or gas) is different from the liquid bulk. In terms of SEI layer, a kind of solid-liquid interface, currently there is no analytical tool which can be used to analyze the SEI layer at a molecular level.In order to analyze the SEI layer in lithium battery, we make the in situ liquid SIMS adoptable in analysis of SEI in lithium-ion batteries, by improving the SALVI (System for Analysis at the Liquid Vacuum Interface) System. An electrolyte comprised of 1.0 M LiPF6 in 1:2 (v/v) ethylene carbonate:dimethyl carbonate (LiPF6 in EC:DMC) was used. The positive and negative secondary ions at the vicinity of the anode surface before and after charging/discharging of the battery were test to determine the molecular structural evolution at the SEI. The in situ liquid SIMS direct observation of molecular information on electrode surface will greatly impact the research work of electrochemical community, especially dealing with liquid/solid interfaces under dynamic operating conditions. The experiment result can also provide very important information for other scientific researches focusing on optimization of battery performance. And based on the results above, the future will be on the in situ (even in operando) investigation of the chemical components and the conditions of the electrode and SEI layer under different electric potential.3. Ionic and molecular distribution and transportation at solid-liquid and gas-liquid interfaces are of great interest in electrochemistry, life science, environmental science, electrocatalysis, material decay and many other fields. However, such information has been difficult to obtain because of the lack of desirable in situ analysis tools in spite of the use of many in situ techniques such as atomic force microscopy, fluorescence, Raman, infrared spectrum, and surface plasmon resonance. In situ liquid SIMS was developed in the last several years and one of its unique capabilities is the analysis of liquid-solid and liquid-vacuum interfaces. However, initial studies reported detection of only negative molecular ions because the signals of the positive ion spectra were too weak to be meaningful. In addition, although negative molecular ions could be successfully analyzed, their signal intensity was not strong. Therefore, the SIMS community has some genuine concern for using this new innovation for further practical applications.In order to improve the intensity of the signals of positive and negative ion, we have conducted comparative experiments on four liquid system (a DBU-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte) with several different conditions of primary ion beam. The signal intensities of molecular ions and characteristic fragment ions are improved by around two orders of magnitude compared with our initial beam condition. The optimized condition can be used to study various aqueous or nonaqueous liquid samples. This study provides a reliable set of conditions to investigate liquid interfaces using in situ liquid SIMS. The goal of next step is to increase the mass resolution of the in situ liquid SIMS analysis, and two methods may be taken into consideration:(i) using some additional hardware parts and (ii) through some improved algorithm. |
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