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Self-excited vibration problems of maglev vehicle-bridge interaction system 被引量:12
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作者 李金辉 李杰 +1 位作者 周丹峰 余佩倡 《Journal of Central South University》 SCIE EI CAS 2014年第11期4184-4192,共9页
The self-excited vibration problems of maglev vehicle-bridge interaction system were addressed, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the... The self-excited vibration problems of maglev vehicle-bridge interaction system were addressed, which greatly degrades the stability of the levitation control, decreases the ride comfort, and restricts the cost of the whole system. Firstly, the coupled model containing the quintessential parts was built, and the mechanism of self-excited vibration was explained in terms of energy transmission from levitation system to bridge. Then, the influences of the parameters of the widely used integral-type proportion and derivation(PD) controller and the delay of signals on the stability of the interaction system were analyzed. The result shows that the integral-type PD control is a nonoptimal approach to solve the self-excited vibration completely. Furthermore, the differential-type PD controller can guarantee the passivity of levitation system at full band. However, the differentiation of levitation gap should be filtered by a low-pass filter due to noise of gap differentiation. The analysis indicates that a well tuned low-pass filter can still keep the coupled system stable. 展开更多
关键词 maglev vehicle-bridge interaction system self-excited vibration energy
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Ligand-dependent aggregation-enhanced photoacoustic of atomically precise metal nanocluster
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作者 Changlin Zhou Meng Wang +6 位作者 Qiaofeng Yao Yu Zhou Chuantao Hou Jianfei Xia Zonghua Wang Jishi Chen Jianping Xie 《Aggregate》 EI CAS 2024年第1期196-203,共8页
Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)... Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)as model NCs,we present a result that weakly polar solvent induces aggregation,which effectively enhances PA intensity and PACE.The PA intensity and PACE are highly dependent on the degree of aggregation,while the aggregation-enhanced PA intensity(AEPA)positively correlates to the protected ligands.Such an AEPA phenomenon indicates that aggregation actually accelerates the intramolecular motion of Au NCs,and enlarges the proportion of excited state energy dissipated through vibrational relaxation.This result conflicts with the restriction of intramolecular motion mechanism of aggregation-induced emission.Further experiments show that the increased energy of AEPA originates from the aggregation inhibiting the intermolecular energy transfer from excited Au NCs to their surrounding medium molecules,including solvent molecule and dissolved oxygen,rather than restricting radiative relaxations.This study develops a new strategy for enhancing the PA intensity of Au NCs,and contributes to a deeper understanding of the origin of the PA signal and the excited state energy dissipation processes for MNCs. 展开更多
关键词 aggregation-enhanced photoacoustic gold nanocluster intermolecular excited state energy transfer intramolecular motion ligand effect
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Effects of substitution of BaF_2 for GdF_3 on optical properties of dense oxyfluoride borogermanate scintillating glasses 被引量:4
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作者 孙心瑗 杨庆梅 +2 位作者 谢鹏 高攀 吴泓澍 《Journal of Rare Earths》 SCIE EI CAS CSCD 2015年第8期800-804,共5页
Eu3+-activated B2O3-GeO2-37Gd2O3-3Eu2O3-(15-x)GdF3-xBaF2 (0≤x≤15) scintillating glasses with the density of 6.1-6.3 g/cm3 were synthesized by a melt-quenching method. The substitution of BaF2 for expensive GdF3... Eu3+-activated B2O3-GeO2-37Gd2O3-3Eu2O3-(15-x)GdF3-xBaF2 (0≤x≤15) scintillating glasses with the density of 6.1-6.3 g/cm3 were synthesized by a melt-quenching method. The substitution of BaF2 for expensive GdF3 in oxyfluoride borogermanate glasses slightly decreased the glass density within 3.0%. Their optical properties were characterized by transmittance, photolumines- cence (excitation and emission), and X-ray excited luminescence (XEL) spectra in detail. The emission intensity of Eu3+ ions increased with the elevated x values. The Eu-O covalancey nature and the local environment of Eu3+ ions were evaluated by Judd-Ofelt results. It was found that the covalency property of Eu-O bond increased with increasing x values. 展开更多
关键词 Eu3+ -actavated bomgermanate scintillating glasses energy transfer Judd-Ofelt theory X-ray excited luminescence rare earths
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氯乙烯在外电场下的激发态结构研究 被引量:5
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作者 周业宏 蔡绍洪 《物理学报》 SCIE EI CAS CSCD 北大核心 2010年第11期7749-7755,共7页
采用密度泛函B3P86方法在6-311G基组上优化了不同外电场作用下氯乙烯分子的基态几何结构、电偶极矩和分子的总能量,然后利用杂化CIS-DFT方法(CIS-B3P86)在相同基组下探讨了无电场时氯乙烯分子前9个激发态的激发能、波长和振子强度和外... 采用密度泛函B3P86方法在6-311G基组上优化了不同外电场作用下氯乙烯分子的基态几何结构、电偶极矩和分子的总能量,然后利用杂化CIS-DFT方法(CIS-B3P86)在相同基组下探讨了无电场时氯乙烯分子前9个激发态的激发能、波长和振子强度和外电场对氯乙烯分子激发态的影响规律.结果表明,分子的几何构型与外电场大小有着强烈的依赖关系.随着外电场的增大,分子总能量先增大后减小,电偶极矩μ先减小后增大.激发能随电场增加快速减小,表明在外电场作用下,氯乙烯分子易于激发和离解.激发态波长随电场的增大而不断增大,且其电子跃迁光谱都集中在紫外区. 展开更多
关键词 激发态 外电场 激发能 振子强度
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电子给受体复合物中电荷转移吸收光谱和溶剂效应 被引量:5
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作者 易海波 李象远 段晓惠 《化学学报》 SCIE CAS CSCD 北大核心 2004年第6期583-586,共4页
用MP2 / 6 3 1G 方法研究了二氯甲烷溶剂分子与电子给体、受体以及电子给受体复合物间的相互作用 ,结果表明 ,二氯甲烷与电子受体和电子给受体复合物间有弱氢键相互作用 .利用CIS/ 6 3 1++G 方法研究了溶剂与溶质分子间形成氢键对激... 用MP2 / 6 3 1G 方法研究了二氯甲烷溶剂分子与电子给体、受体以及电子给受体复合物间的相互作用 ,结果表明 ,二氯甲烷与电子受体和电子给受体复合物间有弱氢键相互作用 .利用CIS/ 6 3 1++G 方法研究了溶剂与溶质分子间形成氢键对激发态的影响 .自然键电荷分析表明 ,电子给受体复合物的S0 →S1跃迁导致一个电子从电子给体转移到受体 .结合非平衡溶剂化处理和自洽反应场方法研究了溶剂分子与复合物间形成氢键时的电荷转移吸收光谱 . 展开更多
关键词 电子给受体复合物 电荷转移吸收光谱 溶剂极化 激发态 氢键 光谱蓝移 溶剂化能 超分子模型 连续介质模型
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磁场对抛物量子点中极化子内部激发态的影响 被引量:2
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作者 乌云其木格 杨洪涛 额尔敦朝鲁 《固体电子学研究与进展》 CAS CSCD 北大核心 2007年第3期285-289,共5页
采用线性组合算符和幺正变换方法研究了外场对抛物量子点中极化子的激发态性质的影响,导出了强、弱耦合情况下极化子的第一内部激发态能量E1、激发能量ΔE、共振频率ω与量子点的有效受限长度l0、电子-声子耦合强度α以及外场B的关系。... 采用线性组合算符和幺正变换方法研究了外场对抛物量子点中极化子的激发态性质的影响,导出了强、弱耦合情况下极化子的第一内部激发态能量E1、激发能量ΔE、共振频率ω与量子点的有效受限长度l0、电子-声子耦合强度α以及外场B的关系。数值计算结果表明,不论强、弱耦合,磁场中量子点内极化子的λ、E1、ΔE和ω都随l0的减小而增大,而且都随回旋频率ωc(磁场B)的增大而增加。另外,在弱耦合情形下,λ、ΔE和ω均与α无关,而E1随α的增大而减小。相反,在强耦合情形下,λ、E、ΔE和ω均随α的增大而增加。 展开更多
关键词 抛物量子点 极化子 第一内部激发态能量 激发能量 共振频率
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Computational Insights into the Excited State Intramolecular Proton Transfer Reactions in Ortho-hydroxylated Oxazolines 被引量:2
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作者 LIU Gai-Mei MA Wei-Jia +2 位作者 WANG Yan YANG Yan SONG Xin-Jian 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2021年第5期540-548,527,共10页
Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-o... Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-ol(DDOP-C_(6)H_(5)) and 4-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-3-hydroxy-benzonitrile(DDOP-CN), have been systematically explored by density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods. Two stable configurations(enol and keto forms) are found in the ground states(S_(0)) for all the compounds while the enol form only exists in the first excited states(S_(1)) for the compound modified with electron donating group(-C_(6)H_(5)). In addition, the calculated absorption and emission spectra of the compounds are in good agreements with the experiments. Infrared vibrational spectra at the hydrogen bond groups demonstrate that the intramolecular hydrogen bond O(1)-H(2)···N(3) in DDOP-C_(6)H_(5) is strengthened in the S_(1) states, while the frontier molecular orbitals further reveal that the ESIPT reactions are more likely to occur in the S_(1) states for all the compounds. Besides, the proton transfer potential energy curves show that the enol forms can barely convert into keto forms in the S_(0) states because of the high energy barriers. Meanwhile, intramolecular proton transfer of all the compounds could occur in S_(1) states. The ESIPT reactions of the ortho-hydroxylated oxazolines are barrierless processes for unsubstituted DDOP and electron withdrawing substituted DDOP-CN, while the electron donating substituted DDOP-C_(6)H_(5) has a small barrier, so the electron donating is unfavorable to the ESIPT reactions of ortho-hydroxylated oxazolines. 展开更多
关键词 excited-state intramolecular proton transfer electron donating group ortho-hydroxylated oxazolines potential energy curves
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强场对Au_4团簇性质的影响 被引量:2
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作者 王红艳 唐永建 +1 位作者 王朝阳 朱正和 《原子与分子物理学报》 CAS CSCD 北大核心 2003年第4期493-496,共4页
采用与时间相关的局域密度泛函 (TDLDA/B3LYP)方法研究Au4团簇的几何构型、分子轨道能级分布和激发能在强激光场中的变化。计算结果表明 :电场不能改变Au4团簇的几何构型 ,随着电场的增加 ,电离势和电子亲和势增加 ,而费米能级和能隙减... 采用与时间相关的局域密度泛函 (TDLDA/B3LYP)方法研究Au4团簇的几何构型、分子轨道能级分布和激发能在强激光场中的变化。计算结果表明 :电场不能改变Au4团簇的几何构型 ,随着电场的增加 ,电离势和电子亲和势增加 ,而费米能级和能隙减小。通过比较不同电场强度下激发能 ,指出要产生超短波脉冲或实现X射线软化 。 展开更多
关键词 团簇 强场 激发能 X射线激光
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Green, orange, and red upconversion luminescence in Nd^(3+)/Yb^(3+): Cs_2NaGdCl_6 powders under 785 nm laser excitation
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作者 王殿元 郭艳艳 +1 位作者 吴杏华 张玉霞 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第6期880-882,共3页
Nd^3+:Cs2NaGdCl6 and Nd^3+, Yb^3+:Cs2NaGdCl6 polycrystalline powder samples were prepared by Morss method E. Under 785 nm semiconductor laser pumping, the upconversion luminescence of Nd^3+ ions in Cs2NaGdCl6 wa... Nd^3+:Cs2NaGdCl6 and Nd^3+, Yb^3+:Cs2NaGdCl6 polycrystalline powder samples were prepared by Morss method E. Under 785 nm semiconductor laser pumping, the upconversion luminescence of Nd^3+ ions in Cs2NaGdCl6 was investigated at room temperature, and three upconversion emissions near 538 nm (Green), 603 nm (Orange), and 675 nm (Red) were observed and assigned to ^4G7/2→^4I9/2, (^4G7/2→^4I11/2; ^4G5/2→^4I9/2), and (^4G7/2→^4I13/2; ^4G5/2→^4I11/2 ), respectively. The dependences of these upconverted emissions on laser power and Nd^3+ ion concentration were investigated, to explore the upconversion mechanism. The effect of doping Yb^3+ ions on the upconversion luminescence of Nd^3+ in Cs2NaGdCl6 was also studied under 785 nm laser excitation. The energy transfer processes were discussed as the possible mechanism for the above upconversion emissions. 展开更多
关键词 upconversion luminescence energy transfer excited state absorption rare earths
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Regulation of Excited-State Intramolecular Proton Transfer Process and Photophysical Properties for Benzoxazole Isothiocyanate Fluorescent Dyes by Changing Atomic Electronegativity
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作者 Hongling Zhang Qingtong Liu +2 位作者 Yiying Wang Zhe Tang Panwang Zhou 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2022年第2期331-337,I0011-I0025,I0003,共23页
Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativit... Excited-state intramolecular proton transfer(ESIPT)is favored by researchers because of its unique optical properties.However,there are relatively few systematic studies on the effects of changing the electronegativity of atoms on the ESIPT process and photophysical properties.Therefore,we selected a series of benzoxazole isothiocyanate fluorescent dyes(2-HOB,2-HSB,and 2-HSe B)by theoretical methods,and systematically studied the ESIPT process and photophysical properties by changing the electronegativity of chalcogen atoms.The calculated bond angle,bond length,energy gap,and infrared spectrum analysis show that the order of the strength of intramolecular hydrogen bonding of the three molecules is 2-HOB<2-HSB<2-HSe B.Correspondingly,the magnitude of the energy barrier of the potential energy curve is 2-HOB>2-HSB>2-HSe B.In addition,the calculated electronic spectrum shows that as the atomic electronegativity decreases,the emission spectrum has a redshift.Therefore,this work will offer certain theoretical guidance for the synthesis and application of new dyes based on ESIPT properties. 展开更多
关键词 excited-state intramolecular proton transfer Photophysical properties energy barrier ELECTRONEGATIVITY
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Upconversion Luminescence of SrTiO3:Er^3+ Ultrafine Powders Produced by 785 nm Laser 被引量:1
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作者 Hai Guo Yan-min Qiao +1 位作者 Ju-fang Zheng Lei-hong Zhao 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 北大核心 2008年第3期233-238,共6页
Er^3+ doped SrTiO3 ultrafine powders were prepared by solid state reaction in a molten NaCl flux. The structural properties were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fo... Er^3+ doped SrTiO3 ultrafine powders were prepared by solid state reaction in a molten NaCl flux. The structural properties were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The Stokes emission spectra of Er^3+ in SrTiO3:Er^3+ ranging from green to near infrared region were investigated under 514.5 nm laser excitation. The green and red upconverted luminescence spectra of Er^3+ were measured under excitation into the 419/2 level by 785 nm laser. The upconversion mechanisms were studied in detail through laser power dependence and Er^3+ ion concentration dependence of upconverted emissions, and results show that excited state absorption and energy transfer process are the possible mechanisms for the upconversion. The upconversion properties indicate that SrTiO3:Er^3+ may be used in upconversion phosphors. 展开更多
关键词 SRTIO3 Upconversion luminescence excited state absorption energy transfer
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Double-excited states of charge transfer band and 4f-4f in single-phase K_(3)Gd(VO_(4))_(2):Tb^(3+)/Sm^(3+) phosphors with superior sensing sensitivity for potential luminescent thermometers 被引量:1
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作者 Yongbin Hua Jae SuYu 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第32期148-159,共12页
Temperature is one of the fundamental parameters for thermodynamics and its accurate detection is necessary.The novel strategy of luminescent materials based on the fluorescence intensity ratio technique has been prom... Temperature is one of the fundamental parameters for thermodynamics and its accurate detection is necessary.The novel strategy of luminescent materials based on the fluorescence intensity ratio technique has been promised for thermometers in more practical environments to overcome the drawbacks of conventional thermometers in recent.Herein,the novel single-phase K_(3) Gd(VO_(4))_(2):Tb^(3+)/Sm^(3+) phosphors were successfully prepared,and the ~4 G_(5/2)→ ~6 H9/2(Sm^(3+)) and ~5 D_(4) → ~7 F_(5)(Tb^(3+)) transitions could be promised for luminescent thermometers.Besides,under the double-excited states of charge transfer band(CTB,317 nm) and 4 f-4 f(478 nm) excitations,the K_(3) Gd(VO_(4))_(2):Tb^(3+)/Sm^(3+) phosphors exhibited different concentration quenching mechanisms in energy transfer processes and also showed superior absolute sensing sensitivity(S_a) and relative sensing sensitivity(S_r).Especially,the maximum S_a and S_r values reached up to 0.568 K^(-1) and 11.24% K^(-1),respectively and the temperature resolution of the KGV:0.2 Tb^(3+)/0.01 Sm^(3+)phosphor was higher than 0.004 K under the excitation wavelength of CTB(317 nm),indicating that the double-excited states in the single-phase KGV:Tb^(3+)/Sm^(3+) phosphors with superior sensing sensitivity could be a novel candidate for potential optical thermometers. 展开更多
关键词 Double-excited lines FIR technique energy transfer Sensing sensitivity
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类锂体系(Z=11~20)1s^24s-1s^2np(5≤n≤9)跃迁能和振子强度的理论计算 被引量:1
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作者 胡木宏 王治文 《原子与分子物理学报》 CAS CSCD 北大核心 2009年第6期993-998,共6页
利用全实加关联的方法计算类锂体系(Z=11~20)1s^24s—1s^2np(5≤n≤9)的跃迁能,将相对论效应(电子动能的相对论修正,Darwin项,电子—电子接触项以及轨道—轨道相互作用)和质量极化效应作为微扰,计算了它们对体系能量的修正.利用得到的... 利用全实加关联的方法计算类锂体系(Z=11~20)1s^24s—1s^2np(5≤n≤9)的跃迁能,将相对论效应(电子动能的相对论修正,Darwin项,电子—电子接触项以及轨道—轨道相互作用)和质量极化效应作为微扰,计算了它们对体系能量的修正.利用得到的波函数和跃迁能计算了核电荷Z=11~20的类锂离子的1s^24s—1s^2np(5≤n≤9)偶极跃迁的长度、速度和加速度三种规范下的振子强度,与现有的实验数据比较,结果符合得很好. 展开更多
关键词 类锂体系 激发态 跃迁能 振子强度
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Gamow-Teller跃迁矩阵元和激发能的统计与分析 被引量:1
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作者 冯丹丹 刘门全 罗志全 《西华师范大学学报(自然科学版)》 2016年第4期425-428,共4页
Gamow-Teller(GT)跃迁对恒星晚期演化和超新星核坍缩中的动力学有重要影响。基于核壳层模型的基础上,应用FFN对GT共振跃迁矩阵元的计算方法,对sd壳层与pf壳层核的GT共振跃迁矩阵元进行计算;根据Hillman的sd壳层与pf壳层中单个粒子的能量... Gamow-Teller(GT)跃迁对恒星晚期演化和超新星核坍缩中的动力学有重要影响。基于核壳层模型的基础上,应用FFN对GT共振跃迁矩阵元的计算方法,对sd壳层与pf壳层核的GT共振跃迁矩阵元进行计算;根据Hillman的sd壳层与pf壳层中单个粒子的能量,对其激发能进行计算,并对数据规律进行分析讨论。一般地,在跃迁轨道相同的情况下,当质子数相同时,跃迁矩阵元随质量数的增加而减小;当质量数相同时,跃迁矩阵元随质子数增加而增加。其结果可为FFN模型的电子俘获率计算提供参考数据,且为其他模型计算的GT跃迁提供对比数据。 展开更多
关键词 跃迁矩阵元 激发能 GT跃迁
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光克洛及其富勒烯复合物光敏性的理论计算 被引量:1
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作者 周彩华 王萌 +3 位作者 胡航艳 张凯悦 郝麟波 李洋 《咸阳师范学院学报》 2017年第4期66-70,共5页
基于密度泛函(DFT)及其时间依赖相关理论(TD-DFT),对应用于光动力疗法的临床光敏剂光克洛(HPPH)与富勒烯C_(60)的3种复合物的基态和激发态性质进行了计算。通过对复合物的几何结构、结合能、电荷布局的计算分析发现,C_(60)与光克洛的卟... 基于密度泛函(DFT)及其时间依赖相关理论(TD-DFT),对应用于光动力疗法的临床光敏剂光克洛(HPPH)与富勒烯C_(60)的3种复合物的基态和激发态性质进行了计算。通过对复合物的几何结构、结合能、电荷布局的计算分析发现,C_(60)与光克洛的卟啉氮原子相互作用的结合能和电荷转移程度较大。对复合物的激发能进行了计算并对吸收光谱进行了模拟,结果显示C_(60)与光克洛复合后降低了最低占据轨道的能量和前线轨道能级间隔,导致复合物的激发能降低,最大吸收峰红移,其中复合物HPPH-C_(60)(1)的最大吸收峰达到了961.69 nm的近红外区。 展开更多
关键词 光敏剂 富勒烯 密度泛函 吸收光谱 激发能
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Spiro-conjugated indenodiarylethenes: enabling steric-induced electronic tuning of photochromic and photoluminescent properties by spiro-conjugation 被引量:1
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作者 Tingting Huang Hongyu Liu +7 位作者 Yawen Bang Yanpei Wang Yuan Liang Xinhao Wang Yang Zhang Sheng Xie Zebing Zeng Ben Zhong Tang 《Science China Chemistry》 SCIE EI CAS CSCD 2020年第11期1659-1665,共7页
Light-operated excited-state photochemical reactions and the resulting photochromic materials have gained significant attention for their promising technological applications in molecular electronic and photonic devic... Light-operated excited-state photochemical reactions and the resulting photochromic materials have gained significant attention for their promising technological applications in molecular electronic and photonic devices.To obtain photochromic materials(e.g.,diarylethenes)with desired properties,the way to tune energy processes of the excited state is essentially important,from both fundamental and practical viewpoints.The modified diarylethenes mostly focused on structural improvements to achieve efficient photochromism.We report here two new spiro-conjugated indenodiarylethenes(named,SFI-Th and SFI-Sul)with an orthogonally arranged spiroπ-scaffold.The spiro fluorene sterically constrains the free volume of photoactive side aromatic rings,while the spiro-conjugation points toward modulation of the decaying channels of excited-state energy,thus allowing for tuning photochromic performances.These spirodiarylethenes SFI-Th and SFI-Sul are readily accessible with low cost and show distinct photochromic and photoluminescent properties.On one hand,the SFI-Th bearing bisthienyl side rings,is an excellent photochromic switch showing high thermal stability and high fatigue resistance in both solution and amorphous state,likely benefited from steric-induced excited-state energy transfer into reversible photochemical reactions,owing to higherπ-orbital spiro-conjugation between the two molecular halves.On the other hand,the SFI-Sul with bissulfonyl side rings,most notably,displays quantitative photocyclization to yield SFI-Sulc upon excitation.However,the ring-closed SFI-Sulc has an extremely slow photocycloreversion,and meanwhile immediately switches on emissive state with a strong fluorescence(Φf=0.57 in amorphous powder state).We study the modulated roles of spiroπ-scaffold in both cases computationally and experimentally,and attribute the facilitated photochemical reaction to the positively electronic effects of spiro-conjugation,and the photo-responsive radiative transition to the negatively electronic effects of sp 展开更多
关键词 diarylethene photochromic reaction spiro-conjugation steric-induced electronic effect excited-state energy
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HD分子X^1∑_g^+,B^1∑_u^+和C^1Ⅱ_u态的势能函数
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作者 尹凯 黄传连 +2 位作者 周玲玲 伍冬兰 谢安东 《四川大学学报(自然科学版)》 CAS CSCD 北大核心 2009年第6期1737-1742,共6页
使用SAC/SAC-CI方法,利用D95++* *、6-311++g* *以及cc-PVTZ等基组,对HD分子的基态(X^1∑_g^+)、第二激发态(B^1∑_u^+)和第三激发态(C^1Ⅱ_u)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了cc-PVTZ基组为... 使用SAC/SAC-CI方法,利用D95++* *、6-311++g* *以及cc-PVTZ等基组,对HD分子的基态(X^1∑_g^+)、第二激发态(B^1∑_u^+)和第三激发态(C^1Ⅱ_u)的平衡结构和谐振频率进行了优化计算.通过对3个基组的计算结果的比较,得出了cc-PVTZ基组为三个基组中的最优基组的结论;使用cc-PVTZ基组,利用SAC的GSUM(Group Sum of Operators)方法对基态(X^1∑_g^+)、SAC-CI的GSUM方法对激发态(B^1∑_u^+)和(C^1Ⅱ_u)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到了相应电子态的完整势能函数;从得到的势能函数计算了与基态(X^1∑_g^+)、第二激发态(B^1∑_u^+)和第三激发态(C^1Ⅱ_u)相对应的光谱常数(B_e,α_e,ω_e和ω_eχ_e),结果与实验数据基本吻合. 展开更多
关键词 分子 势能函数 ground state 三激发态 SAC excited states 基组 basis sets MURRELL-SORBIE函数 energy calculation 优化计算 function three 基态 方法 least square methods for 正规方程组 AGREEMENT 谐振频率
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稀土发光材料(La_(1-x)Gd_x)OBr:Tb,Ce中的能量传递
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作者 伍瑜 唐虹 诸葛星 《北京科技大学学报》 EI CAS CSCD 北大核心 1992年第2期271-276,共6页
在紫外光激发下,(La_(1-x)Gd_x)OBr:Tb_(0.0075),Ce_y中Gd^(5+)、Ce^(3+)、Tb^(3+)可各自吸收激发能。Ce^(3+)和Tb^(3+)发光,Ge^(3+)不发光,但可将能量传递给Ce^(3+)和Tb^(3+)发光。Ce^(3+)和Tb^(3+)之间可能有可逆的能量传递。Gd的存... 在紫外光激发下,(La_(1-x)Gd_x)OBr:Tb_(0.0075),Ce_y中Gd^(5+)、Ce^(3+)、Tb^(3+)可各自吸收激发能。Ce^(3+)和Tb^(3+)发光,Ge^(3+)不发光,但可将能量传递给Ce^(3+)和Tb^(3+)发光。Ce^(3+)和Tb^(3+)之间可能有可逆的能量传递。Gd的存在改变晶场分布,使Ce^(3+)激发带长波端红移,有利于Tb^(3+)+5D_3→Ce^(3+)→Tb^(3+5)D_4的能量传递,敏化人眼敏感的绿光发射,也有利于Tb^(3+)和Ce^(3+)发光的温度稳定性。 展开更多
关键词 稀土 发光材料 能量传递 激发能
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Super twisting sliding mode approach applied to voltage orientated control of a stand-alone induction generator
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作者 Yacine Bendjeddou Abdelhakim Deboucha +2 位作者 Larafi Bentouhami Elkheir Merabet Rachid Abdessemed 《Protection and Control of Modern Power Systems》 2021年第1期233-241,共9页
To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting s... To enhance the robustness and dynamic performance of a self-excited induction generator (SEIG) used in a stand-alone wind energy system (WES), a virtual flux oriented control (VFOC) based on nonlinear super-twisting sliding mode control (STSMC) is adopted. STSMC is used to replace the conventional proportional-integral-Fuzzy Logic Controller (PI-FLC) of the inner current control loops. The combination of the proposed control strategy with space vector modulation (SVM) applied to a PWM rectifier brings many advantages such as reduction in harmonics, and precise and rapid tracking of the references. The performance of the proposed control technique (STSMC-VFOC-SVM) is verified through simulations and compared with the traditional technique (PI-FLC-VFOC-SVM). It shows that the proposed method improves the dynamics of the system with reduced current harmonics. In addition, the use of a virtual flux estimator instead of a phase-locked loop (PLL) eliminates the line voltage sensors and thus increases the reliability of the system. 展开更多
关键词 Self-excited induction generator Virtual flux oriented control Back-to-back converter Super twisting sliding mode control PI-fuzzy controller wind energy
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Two-Photon Dissociation Dynamics of Hydroxyl Radical
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作者 Ge Sun Xian-feng Zheng +4 位作者 Yuan Qin Yu Song Jingsong Zhang Jose Martin Amero Gabriel J.Vázquez 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第2期129-134,I0002,共7页
Two-photon dissociation dynamics of the OH radical is studied using the high-n Rydberg atom time-of-flight(HRTOF) technique. The H(2 S)+O(1 D) and H(2 S)+O(1 S) product channels are observed in the dissociation of the... Two-photon dissociation dynamics of the OH radical is studied using the high-n Rydberg atom time-of-flight(HRTOF) technique. The H(2 S)+O(1 D) and H(2 S)+O(1 S) product channels are observed in the dissociation of the OH radical on the 22Π and B2Σ+repulsive states, respectively, from sequential two-photon excitation via the A2Σ+(v′=2, J′=0.5-2.5)state. Both H+O product channels have anisotropic angular distributions, with β=-0.97 for H(2 S)+O(1 D) and 1.97 for H(2 S)+O(1 S). The anisotropic angular distributions are consistent with a mechanism of OH direct dissociation on the repulsive potential energy curves(PECs) leading to the H+O products. The OH bond dissociation energy D0(O-H) is determined to be 35580±15 cm-1. 展开更多
关键词 PHOTODISSOCIATION Hydroxyl radical excited state Potential energy curves
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