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The atomic layer etching of molybdenum disulfides using low-power oxygen plasma
摘要： The layered removal mechanisms of molybdenum disul?des (MoS2) using low-power oxygen plasma are investigated in this paper. After the low-power oxygen plasma treatment, the topmost MoS2 layer is completely oxidized. The weaker adhesion of Mo oxides with MoS2 surfaces would lead to the detachment of the topmost oxidized MoS2 layer from the underlying MoS2 ?lms. Since MoS2 is insoluble and Mo oxides are soluble in water, an additional dipping procedure of the sample in de-ionized water will help with the complete detachment of the topmost oxidized MoS2 layer. With a re-sulfurization procedure after the removal process, the partially oxidized MoS2 ?lm remaining on the substrate can be recovered back to a complete MoS2 ?lm. Both optical and electrical characteristics of the MoS2 ?lms can be maintained after the removal procedure. By repeating the same procedure, a layer-by-layer removal of MoS2 is demonstrated, which provides an easy and fast approach to determine the number of layers of the 2D material.
关键词： layered removal,oxygen plasma,layer number controllability
更新于2025-11-14 17:03:37
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Design and Evaluation of a Permanently Installed Plane-Based Calibration Field for Mobile Laser Scanning Systems
摘要： Mobile laser scanning has become an established measuring technique that is used for many applications in the fields of mapping, inventory, and monitoring. Due to the increasing operationality of such systems, quality control w.r.t. calibration and evaluation of the systems becomes more and more important and is subject to on-going research. This paper contributes to this topic by using tools from geodetic configuration analysis in order to design and evaluate a plane-based calibration field for determining the lever arm and boresight angles of a 2D laser scanner w.r.t. a GNSS/IMU unit (Global Navigation Satellite System, Inertial Measurement Unit). In this regard, the impact of random, systematic, and gross observation errors on the calibration is analyzed leading to a plane setup that provides accurate and controlled calibration parameters. The designed plane setup is realized in the form of a permanently installed calibration field. The applicability of the calibration field is tested with a real mobile laser scanning system by frequently repeating the calibration. Empirical standard deviations of <1 ... 1.5 mm for the lever arm and <0.005? for the boresight angles are obtained, which was priorly defined to be the goal of the calibration. In order to independently evaluate the mobile laser scanning system after calibration, an evaluation environment is realized consisting of a network of control points as well as TLS (Terrestrial Laser Scanning) reference point clouds. Based on the control points, both the horizontal and vertical accuracy of the system is found to be < 10 mm (root mean square error). This is confirmed by comparisons to the TLS reference point clouds indicating a well calibrated system. Both the calibration field and the evaluation environment are permanently installed and can be used for arbitrary mobile laser scanning systems.
关键词： plane-based calibration field,evaluation,configuration analysis,mobile laser scanning,control points,accuracy,TLS reference point clouds,boresight angles,controllability,lever arm
更新于2025-09-23 15:19:57
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Controlled gel research: the effect of ethanol for delaying the polycondensation of tetraethyl orthosilicate-dimethyldiethoxysilane
摘要： In this study, the effect of ethanol for delaying the polycondensation of silanol in the co-hydrolysis-condensation of tetraethyl orthosilicate-dimethyldiethoxysilane was first explored and demonstrated by varying the amount of ethanol under low-water content and acid-catalyzed. On the basis of this, the controllability of the sol-gel process is realized, and the calculation formula of the gel formation time is provided. The experiment shows that the storage gel time and the reaction gel time are extended from 75 h to at least 4584 h, or from 20 to 65 h with the increase of ethanol concentration, respectively. And we observed the microscopic process of solution-sol-gel transition by light transmission microscope. The sol-gel process established in this experiment gives a mechanism reference for future research.
关键词： Polycondensation,Sol-gel process,Delay,Gel time,Controllability
更新于2025-09-16 10:30:52
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Any quantum network is structurally controllable by a single driving signal
摘要： Control theory concerns with the questions if and how it is possible to drive the behavior of a complex dynamical system. A system is said to be controllable if we can drive it from any initial state to any desired state in finite time. For many complex networks, the precise knowledge of system parameters lacks. But, it is possible to make a conclusion about network controllability by inspecting its structure. Classical theory of structural controllability is based on the Lin’s structural controllability theorem, which gives necessary and sufficient conditions to conclude whether a network is structurally controllable. Due to this fundamental theorem, we may identify a minimum driver vertex set, whose control with independent driving signals is sufficient to make the whole system controllable. I show that Lin’s theorem does not apply to quantum networks, if local operations and classical communication between vertices are allowed. Any quantum network can be modified to be structurally controllable obeying a single driving vertex.
关键词： Quantum networks,Linear quantum dynamics,Controllability
更新于2025-09-09 09:28:46