测量铜原子亚稳态密度的饱和吸收法

提出了测量连续脉冲放电余辉期激活粒子亚稳态密度的饱和吸收方法,在两台分别作为探测光源和吸收池的溴化亚铜激光器测量系统中得到证实。观察和讨论了D_(5/2)亚稳态能级布居在脉冲间隔的弛豫特性。     

自终止跃迁机制和R-M激光

众所周知,以铜蒸气激光器为代表的脉冲放电激励的金属蒸气激光器件属于通常的三能级系统,其激光上能级应是与基态有最强光学联系的共振态,而激光下能级则是与基态光学跃迁禁戒的亚稳态,在玻恩近似得以成立的条件下,同一能级的电子碰撞激发速率与自发跃迁速率正关联,因此共振态有可能优于亚稳态被布居形成粒子数反转导致激光．由于激光下能级与基态之间的光学跃迁禁戒,所以激光跃迁将造成其粒子数堆积,激光最终必将自动终止,因此习惯上称作为“自终止跃迁激光器”． 我们完成了包括铜蒸气激光器在内的脉冲放电激励的多种金属蒸气“…     

铅蒸气激光器

我们利用实验室里现有的进行铜蒸气激光实验的装置,进行了Au、Ba、Pb等蒸气激光器的实验。本文主要报告Pb蒸气激光器(7229(?)波长)的实验结果。 铅原子的基态是6p~2(3p),上激光能级是第一共振能级6s~26P7s(~3p_1~0),7229(?)波长的下激光能级是6S~26p~2(~1D_2),有关能级图见图10但是,激光跃迁~3p_1~0→~1D_2是三重态到单重态的跃迁,在L-S耦     

利用HCD灯进行U激光敏化荧光光谱测量

利用直流稳定放电的Kr-U HCD灯作为放电等离子体源,在591.54nm波长对U原子进行共振激发,在400～800nm波长范围内观察到了几百条激光敏化荧光光谱线,并由此测定了UHCD灯中相应能级集居数增量的分布。     

用HCD灯作金属原子蒸气源的激光光谱研究

利用Ne-Cu HCD灯研究了金属原子蒸气源的光电流光谱和激光荧光光谱,发现了Cu 4p~2P_(3/2)能级的表观寿命随灯电流增加而增大。认为这一现象起因于“共振俘获”效应。     

铜离子空心阴极连续红外激光器

近年来人们对铜离子蒸气激光器广泛地进行了研究。从1974年报导了GuⅡ7808且[3d~96s~3D_3—3d~95p~3F_4~0]的激光跃迁后,相继又发表了铜离子的其他激光跃迁。为了探讨空心阴极的放电特性,进行铜空心阴极放电研究,我们研制了GuⅡ7808且激光器。采用矩形槽空心阴极,铜蒸气由阴极铜棒放电溅射产生,在纯He以及He-Ne、He-Ar、He-Xe放电中都获得了激光输出。     

铜蒸气激光振荡自终止的再认识

铜蒸气激光器是典型的自终止激光器,其激光跃迁通道的下能级是与基态没有光学联系的亚稳态,积累的布居将自动地终止激光。与早先认为主要是激光跃迁本身造就了亚稳态的布居不同,对放电激励的铜蒸气激光器,电子与基态铜原子的碰撞形成对亚稳态的持续激励,电子与激光上能级铜原子的碰撞随着电子温度的降低构成强的消激励作     

利用脉冲空心阴极放电技术实现Kr原子级联双光子电离

高压脉冲放电后,Kr-U空心阴极放电(HCD)灯中的Kr原子有相当数量布居在长寿命的亚稳态1S_5(5_3P_2~0)上。我们利用两台可调谐脉冲染料激光器,首次实现了从(用脉冲HCD布居的)Kr原子)1S_5(5~3P_2~0)亚稳态开始抽运的两步级联光电离,从而为探测Kr等惰性气体原子的高激发态、Pydberg态及自电离态的性质提供了一种简便的实验方法。我们利用这一技     

激光诱导镁单光子S—D,S—S跃迁

本文报导镁金属蒸气中,激光诱导的Mg 3s4s~1S_0—3snd~1D_2,3sns~1S_0(n=22—34)禁戒跃迁。 在热管炉中加热形成镁蒸气,P_(Mg)=0.1Torr,缓冲气体为氩气,P_(Ar)=10Torr。 实验利用两束纳秒脉冲染料激光,第一束峰值功率5×10~5W/cm~2,波长固定在3s~(21)S_0—3s4s~1S_0双光子共振波长(459.72nm)。第二束激光峰值功率10~7W/cm~2,波长在550nm—560nm之间扫描。探测到镁三个里德堡态系列的共振电离谱,一个是     

铜蒸气激光器实现32瓦运转

铜蒸气激光器是一种自终止跃迁的高增益气体放电激光器,它能实现高功率、高效率运转.它的发射为可见光谱绿线(510.6nm)和黄线(578.2nm).我所自从1983年开展铜蒸气激光器的研究工作以来,先后在(?)23×1000mm的放电器件上.用6～10kHz的脉冲重复频率实现了10W、15W、23W的运转;工作寿命超过200小时.去年,我们在(?)35×     

2D and 3D Hybrid Systems for Enhancement of Chondrogenic Differentiation of Tonsil‐Derived Mesenchymal Stem Cells

2D/3D hybrid cell culture systems are constructed by increasing the temperature of the thermogelling poly(ethylene glycol)‐poly(l ‐alanine) diblock copolymer (PEG‐l ‐PA) aqueous solution in which tonsil tissue‐derived mesenchymal stem cells and graphene oxide (GO) or reduced graphene oxide (rGO) are suspended, to 37 °C. The cells exhibit spherical cell morphologies in 2D/3D hybrid culture systems of GO/PEG‐l ‐PA and rGO/PEG‐l ‐PA by using the growth medium. The cell proliferations are 30%–50% higher in the rGO/PEG‐l ‐PA hybrid system than in the GO/PEG‐l ‐PA hybrid system. When chondrogenic culture media enriched with TGF‐β3 is used in the 2D/3D hybrid systems, cells extensively aggregate, and the expression of chondrogenic biomarkers of SOX 9, COL II A1, COL II, and COL X significantly increases in the GO/PEG‐l ‐PA 2D/3D hybrid system as compared with the PEG‐l ‐PA 3D systems and rGO/PEG‐l ‐PA 2D/3D hybrid system, suggesting that the GO/PEG‐l ‐PA 2D/3D hybrid system can be an excellent candidate as a chondrogenic differentiation platform of the stem cell. This paper also suggests that a 2D/3D hybrid system prepared by incorporating 2D materials with various surface biofunctionalities in the in situ forming 3D hydrogel matrix can be a new cell culture system.     

Synthesis of two-dimensional/one-dimensional heterostructures with tunable width

Two-dimensional/one-dimensional (2D/1D) heterostructures as a new type of heterostructure have been studied for their unusual properties and promising applications in electronic and optoelectronic devices.However,the studies of 2D/1 D het-erostructures are mainly focused on vertical heterostructures,such as MoS2 nanosheet-carbon nanotubes.The research on later-al 2D/1D heterostructures with a tunable width of 1D material is still scarce.In this study,bidirectional flow chemical vapor de-position (CVD) was used to accurately control the width of the WS2/WSe2 (WS2/MoS2) heterostructures by controlling reacting time.WSe2 and MoS2 with different widths were epitaxially grown at the edge of WS2,respectively.Optical microscope,atomic force microscope (AFM),and scanning electron microscope (SEM) images show the morphology and width of the heterostruc-tures.These results show that the width of the heterostructures can be as low as 10 nm by using this method.The interface of the heterostructure is clear and smooth,which is suitable for application.This report offers a new method for the growth of 1D nanowires,and lays the foundation for the future study of the physical and chemical properties of 2D/1D lateral heterostruc-tures.     

Survey of software defined D2D and V2X communication

The related D2D (device-to-device) and V2X (vehicle-to-everything) are regarded as vital components of 5G communication system,which providing alternative network services and multiple application services for cellular network.In the meanwhile,SDN (software defined networking) can improve the compatibilities and flexibilities of D2D and V2X.SD-D2D (software defined D2D communication) and SD-V2X (software defined V2X communication) technologies were reviewed.Based on their similarities and respective characteristics,their state-of-arts and architectures were reviewed accordingly,and the key technologies such as D2D location/discovery management,D2D routing control,D2D flow table management,V2V path scheduling,and V2V path recovery were analyzed.Finally,it was pointed out that the SD-D2D architecture was approaching mature and the SD-V2X framework had been preliminarily determined,the existing problems of interference management,mobile management and routing management in D2D/V2X communication could be effectively solved.Furthermore,it was also pointed out that the disconnection between the existing SD-D2D/V2X studies and the actual application needed to be overcome.     

2D Nanomaterial Arrays for Electronics and Optoelectronics

Two‐dimensional (2D) materials, benefitting from their unique planar structure and various appealing electronic properties, have attracted much attention for novel electronic and optoelectronic applications. As a basis for practical devices, the study of micro/nano‐2D material arrays based on coupling effects and synergistic effects is critical to the functionalization and integration of 2D materials. Moreover, micro/nano‐2D material arrays are compatible with traditional complementary metal oxide semiconductor (CMOS) electronics, catering well to high‐integration, high‐sensitivity, and low‐cost sensing and imaging systems. This review presents some recent studies on 2D material arrays in sequence from their novel preparations to high‐integration applications as well as explorations on dimension tuning. A first focus is on various typical fabrication methods for 2D material arrays, including photolithography, 2D printing, seeded growth, van der Waals epitaxial growth, and self‐assembly. Then, the applications of 2D material arrays, such as field effect transistors, photodetectors, pressure sensors, as well as flexible electronic devices of photodetectors and strain sensors, are elaborately introduced. Furthermore, the recent burgeoning exploration of mixed‐dimensional heterostructure arrays including 0D/2D, 1D/2D, and 3D/2D is discussed. Ultimately, conclusions and an outlook based on the current developments in this promising field are presented.     

Cs(7DJ)+H2的反应与非反应碰撞转移截面的测定

利用激光泵浦-吸收技术,研究了在样品池中的Cs(7D_J)+H₂→CsH[X¹∑+(v″=0)]+H光化学反应过程。双光子激发Cs-H₂混合蒸气中Cs原子至7²D态,荧光中除有泵浦能级发生的直接荧光外,还包含由精细结构碰撞转移产生的敏化荧光,CsH分子是由7D原子与H₂间的三体碰撞反应产生的。利用780 nm激光测量了CsH X¹∑+(v″=0→v″=21)吸收带。△Ⅰ′和△Ⅰ″分别表示泵浦7D_3/2和7D_5/2时的吸收光强。解速率方程组,得到7D_3/2→7D_5/2和7D_5/2→7D_3/2精细结构转移截面分别为(1.3±0.3)×10^-14和(9.8±2.0)×10^-15cm²。从7D_J碰撞到7D以外态的截面分别为(4.0±1.0)×10^-15(对J=3/2)和(3.6+0.9)×10^-15cm²(对J=5/2)。Cs(7D_J)+H₂→CsH+H的反应截面分别是(1.4±0.5)×10^-16(J=3/2)和(1.1±0.4)×10^-16cm²(J=5/2),7D_3/2与H₂的反应活动...更多性大于7D_5/2。     

On the automorphism group of various Goppa codes

We determine the automorphism group of various Goppa codes 𝒞 _L(D,G) associated with certain function fields F/F _q of genus g>0. It is well known that, for deg D=n>2g+2, the automorphism group {Aut_D,G(F/F_q) can be embedded into Aut(𝒞_L(D,G)) as a subgroup. We show that, under certain conditions on the divisors D and G Aut_D,G(F/F_q ) is actually isomorphic to Aut(𝒞_L(D,G))     

Asymptotic rate-distortion functions for coding precedence relations (Corresp.)

An improved analysis for an information system is described in which the input and output alphabets consist of (equiprobable) ordered lists of m items, with two distortion criteria: 1) the fraction of item-pairs found out of order and 2) the fraction of items found in wrong positions. For the former it is shown that, asm rightarrow infty, the rate-distortion functionR_{1} (D)is equivalent tomG(D)with, for smallD,G(D)=log (2/D)-2+ O(D). For the latter,R_{2} (D) = m log m(1 - D) + m(l - D)[log(1 - D) - 1] + o(m).     

LTE与D2D异构网络的应用场景分析

文章首先介绍了LTE/D2D异构网络的发展背景。针对目前研究所涉及到的应用场景的多样性与差异性,我们对其进行了归纳分析。通过对LTE/D2D异构网络应用场景的分析,可以看出LTE/D2D异构网络具有极其广泛的前景,并且能有效节约信道资源、提高网络容量。     

Functional 2D Phases in Mixed Dimensional Perovskite Photovoltaics

Organic-inorganic hybrid perovskite solar cells (PSCs) with unique properties exhibit their powerful competitiveness in the photovoltaic field over the past few years. However, the challenges of stability for perovskite devices limit the commercialization and further development. The 2D/3D hybrid structures combine the superior efficiency of bulk perovskites and the superior stability of layered perovskites and gradually get hotspots of the photovoltaic field. In addition, there remains a lack of comprehensive understanding and systematic summary of the function of 2D perovskite attributed to the complex nature of 2D/3D structures. Here, the latest progress of 2D/3D hybrid structures and focus on the functionality of 2D phases in mixed structures and the underlying mechanism from the perspective of their different distributions in the perovskite layer is summarized. Then, the insight and vital factors for overall improvements in the stability of 2D/3D structures are thoroughly discussed. Finally, it is expected that this review will contribute to the present challenges and future research prospects in the photovoltaic industry.