Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for...Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for their broad applications in high-performance integrated devices, such as broad-band photodetectors, multi-color light emitting diodes （LEDs）, and high-efficiency photovoltaic devices. In this review, we will summarize the recent progress on the controlled growth of composition modulated atomically thin 2D semiconductor alloys with band gaps tuned in a wide range, as well as their induced applications in broadly tunable optoelectronic components. The band gap engineered 2D semiconductors could open up an exciting opportunity for probing their fundamental physical properties in 2D systems and may find diverse applications in functional electronic/optoelectronic devices.展开更多
The purpose of this contribution was to evaluate a recently published atom model for Helium, characterized by a double rotation of the electrons which exhibit perpendicular rotation axes. Thereby, each rotation is ind...The purpose of this contribution was to evaluate a recently published atom model for Helium, characterized by a double rotation of the electrons which exhibit perpendicular rotation axes. Thereby, each rotation is induced by the spin of one electron?[1]. Hereto, a tangible mechanical model was used which facilitated to derive the mathematical formulae as the basics for two-dimensional projections, and—not least—for a digital animation yielding freeze images from different perspectives. The resulting shape of the electron shell turned out to be not spherical. In particular, the total velocity of the electrons is variable since the relative running direction may change—in contrast to the initial assumption—, even leading to an intermittent standstill, and implying a variable kinetic energy. Thus it can be concluded that this model describes a rotating rotor but not the Helium atom, and that it must be abandoned.展开更多
We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found th...We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.展开更多
In order to apply the recently published planar atom model of Helium with well-defined electron trajectories onto the results about the thermal radiative behaviour of gases,which was published by the author in 2016,th...In order to apply the recently published planar atom model of Helium with well-defined electron trajectories onto the results about the thermal radiative behaviour of gases,which was published by the author in 2016,the latter publication had to be partly questioned since its theoretical evaluation contains several errors.Nevertheless,the basic statements made therein,applying the kinetic gas theory,are still valid.Since they cannot be assumed as commonly known,first,the description of the measurement equipment and the applied light sources,the most relevant results,and the basic theoretical interpretation were recapitulated.The essential empirical result of those measurements was the observation that any gas is warmed up when it is thermally irradiated,but solely up to a limiting temperature where the absorption intensity of the gas is equal to its emission intensity.This effect was first observed in air and in CO_(2),whereby the limiting temperatures were nearly equal.But it also occurred in the noble gases Argon,Neon and Helium,whereby the limiting temperatures depended on the type of gas.These differences could be explained by means of the kinetic gas theory,assuming proportionality between the collision wattage of the atoms and the radiation wattage.As a consequence,an additional energy must exist,which does not appear in the classic thermodynamic theory,and which must be due to an oscillating process at the electrons.In order to explain this,using the example of Helium,the said atom model is adduced.Since it exhibits well-defined electron trajectories—in contrast to the orthodox orbital model where the electrons underlie probabilities of presence—such an oscillation process,implicating an excited state of the electrons,is well describable.Thereto,a modified harmonic oscillator comes into question.This oscillator is eccentric since it rotates around the nucleus.Moreover,it is asymmetric since its energetic conditions are asymmetric with respect to the orbit path.In particular,the quantum-mechanical condition of a standing wave must be fulfilled,i.e.the angular velocityωosc of the oscillator must be an integer multiple of the angular rotation velocityωrot,preferably 2.By equating the oscillation energy of the electrons and the radiation energy,which is determined by Einstein’s equation for the photoelectric effect,and by applying the theorem of conservation of momentum P onto the collision process,thermodynamics could be bridged with quantum mechanics,delivering in the excited state an elliptic orbit.The essential difference between the orthodox and the alternative model consists in the fact that the orthodox model only considers the observers’point of view,whereas the alternative model distinguishes between object and observer.Thereby,the isolated model is two-dimensional,obeying the here described quantum mechanical computation,whereas from the viewpoint of the observer,it is three-dimensional,due to the thermally induced rotation.展开更多
水和冰在自然界中广泛存在,冰的结构与成核生长在材料科学、摩擦学、生物学、大气科学以及行星科学等众多领域具有至关重要的作用,如生物抗冻蛋白的抗结冰机理、抗结冰材料的研制、冰川间的相对滑移、大气臭氧降解催化、云和降水的形成...水和冰在自然界中广泛存在,冰的结构与成核生长在材料科学、摩擦学、生物学、大气科学以及行星科学等众多领域具有至关重要的作用,如生物抗冻蛋白的抗结冰机理、抗结冰材料的研制、冰川间的相对滑移、大气臭氧降解催化、云和降水的形成等.这些过程往往与微观尺度上水分子与表面或者水分子之间的相互作用相关.受限于之前的研究方法和手段,尽管存在大量的实验和理论研究,冰成核和生长的微观机理却仍旧存在许多争议与疑问.因此,从原子尺度上对冰结构和成核生长过程进行准确的表征和研究具有极为重要的意义.近期,我们利用非接触式原子力显微镜(Non-Contact Atomic Force Microscope,NC-AFM),通过对qPlus针尖进行化学修饰,借助针尖与水分子之间的高阶静电力和泡利排斥力,成功实现了Au(111)表面上二维冰结构及其边界的高分辨成像,首次在原子尺度上揭示了二维冰成核生长的过程和机理,为疏水金属表面冰的初期生长提供了全新的认识.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11374092,61474040,61574054,and 61505051)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province,Chinathe Science and Technology Department of Hunan Province,China(Grant No.2014FJ2001)
文摘Atomically thin two-dimensional （2D） layered materials have potential applications in nanoelectronics, nanophoton- ics, and integrated optoelectronics. Band gap engineering of these 2D semiconductors is critical for their broad applications in high-performance integrated devices, such as broad-band photodetectors, multi-color light emitting diodes （LEDs）, and high-efficiency photovoltaic devices. In this review, we will summarize the recent progress on the controlled growth of composition modulated atomically thin 2D semiconductor alloys with band gaps tuned in a wide range, as well as their induced applications in broadly tunable optoelectronic components. The band gap engineered 2D semiconductors could open up an exciting opportunity for probing their fundamental physical properties in 2D systems and may find diverse applications in functional electronic/optoelectronic devices.
文摘The purpose of this contribution was to evaluate a recently published atom model for Helium, characterized by a double rotation of the electrons which exhibit perpendicular rotation axes. Thereby, each rotation is induced by the spin of one electron?[1]. Hereto, a tangible mechanical model was used which facilitated to derive the mathematical formulae as the basics for two-dimensional projections, and—not least—for a digital animation yielding freeze images from different perspectives. The resulting shape of the electron shell turned out to be not spherical. In particular, the total velocity of the electrons is variable since the relative running direction may change—in contrast to the initial assumption—, even leading to an intermittent standstill, and implying a variable kinetic energy. Thus it can be concluded that this model describes a rotating rotor but not the Helium atom, and that it must be abandoned.
基金the National Natural Science Foundation of China(Grant No.11205001)the National Basic Research Program of China(Grant No.2010CB234607)the Postdoctoral Science Foundation of Anhui University,China
文摘We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.
文摘In order to apply the recently published planar atom model of Helium with well-defined electron trajectories onto the results about the thermal radiative behaviour of gases,which was published by the author in 2016,the latter publication had to be partly questioned since its theoretical evaluation contains several errors.Nevertheless,the basic statements made therein,applying the kinetic gas theory,are still valid.Since they cannot be assumed as commonly known,first,the description of the measurement equipment and the applied light sources,the most relevant results,and the basic theoretical interpretation were recapitulated.The essential empirical result of those measurements was the observation that any gas is warmed up when it is thermally irradiated,but solely up to a limiting temperature where the absorption intensity of the gas is equal to its emission intensity.This effect was first observed in air and in CO_(2),whereby the limiting temperatures were nearly equal.But it also occurred in the noble gases Argon,Neon and Helium,whereby the limiting temperatures depended on the type of gas.These differences could be explained by means of the kinetic gas theory,assuming proportionality between the collision wattage of the atoms and the radiation wattage.As a consequence,an additional energy must exist,which does not appear in the classic thermodynamic theory,and which must be due to an oscillating process at the electrons.In order to explain this,using the example of Helium,the said atom model is adduced.Since it exhibits well-defined electron trajectories—in contrast to the orthodox orbital model where the electrons underlie probabilities of presence—such an oscillation process,implicating an excited state of the electrons,is well describable.Thereto,a modified harmonic oscillator comes into question.This oscillator is eccentric since it rotates around the nucleus.Moreover,it is asymmetric since its energetic conditions are asymmetric with respect to the orbit path.In particular,the quantum-mechanical condition of a standing wave must be fulfilled,i.e.the angular velocityωosc of the oscillator must be an integer multiple of the angular rotation velocityωrot,preferably 2.By equating the oscillation energy of the electrons and the radiation energy,which is determined by Einstein’s equation for the photoelectric effect,and by applying the theorem of conservation of momentum P onto the collision process,thermodynamics could be bridged with quantum mechanics,delivering in the excited state an elliptic orbit.The essential difference between the orthodox and the alternative model consists in the fact that the orthodox model only considers the observers’point of view,whereas the alternative model distinguishes between object and observer.Thereby,the isolated model is two-dimensional,obeying the here described quantum mechanical computation,whereas from the viewpoint of the observer,it is three-dimensional,due to the thermally induced rotation.
文摘水和冰在自然界中广泛存在,冰的结构与成核生长在材料科学、摩擦学、生物学、大气科学以及行星科学等众多领域具有至关重要的作用,如生物抗冻蛋白的抗结冰机理、抗结冰材料的研制、冰川间的相对滑移、大气臭氧降解催化、云和降水的形成等.这些过程往往与微观尺度上水分子与表面或者水分子之间的相互作用相关.受限于之前的研究方法和手段,尽管存在大量的实验和理论研究,冰成核和生长的微观机理却仍旧存在许多争议与疑问.因此,从原子尺度上对冰结构和成核生长过程进行准确的表征和研究具有极为重要的意义.近期,我们利用非接触式原子力显微镜(Non-Contact Atomic Force Microscope,NC-AFM),通过对qPlus针尖进行化学修饰,借助针尖与水分子之间的高阶静电力和泡利排斥力,成功实现了Au(111)表面上二维冰结构及其边界的高分辨成像,首次在原子尺度上揭示了二维冰成核生长的过程和机理,为疏水金属表面冰的初期生长提供了全新的认识.
