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Double [5]carbohelicene: facile synthesis, chiroptical properties,isomerization study, and lasing application

Science China Chemistry 2025年第1期 233-240页

作者： Peipei Liu Yantong Li Meng-Xiang Wu Hao Kang Xiao-Li Zhao Lin Xu Linlin Liu Xiaodong Li Junfeng Fang Zhiwei Fang Ya Cheng Hai-Bo Yang Huakang Yu Xueliang Shi state key laboratory of Petroleum Molecular & Process Engineering Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular Engineering East China Normal University School of physics and Optoelectronics South China University of Technology Institute of Polymer Optoelectronic Materials & Devices State Key Laboratory of Luminescent Materials & Devices South China University of Technology School of physics and Electronic Science Engineering Research Center of Nanophotonics & Advanced Instrument Ministry of EducationEast China Normal University state key laboratory of precision spectroscopy School of Physics and Electronic Science East China Normal University

Double carbohelicenes have attracted considerable attention due to their aesthetic structures, distinct π-conjugation extension, inherent chirality, and intriguing optical and electronic properties. Herein, the concise de novo synthesis of a new double[5]carbohelicene 1 together with its chiroptical properties, isomerization process and lasing application is presented. 1 was synthesized by a simple protocol involving the formation of a 6,6′-bipentacene as the key intermediate. It is worth noting that1 existed as two diastereomers 1-PP/MM and 1-PM, which were successfully isolated and unambiguously confirmed by Xray crystallography. The optical resolution of the racemic 1-PP/MM was successfully achieved by chiral-phase highperformance liquid chromatography（HPLC）, and 1-PP and 1-MM were characterized by circular dichroism. Interestingly, it was found that 1-PP/MM could be completely isomerized to 1-PM upon heating, and the detailed thermodynamics and kinetics of the isomerization process were systematically investigated. 1-PM exhibited deep-red luminescence with emission maximum at 723 nm and fluorescence quantum yield as high as 32.95%. Consequently, we can showcase the lasing application of 1-PM by doping with epoxy resin to assemble a bottle microlaser spontaneously, which the lasing wavelength is 796.6 nm at a threshold of 0.8 m J cm-2. We believe that our studies, including the facile synthesis methodology, detailed isomerization studies, and lasing application, will shed some light on the design and synthesis of novel carbohelical systems with more functions.

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Rotational Analysis of A2Πu-X2Πg System of 16O2+ Cation

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Chinese Journal of Chemical physics 2014年第2期27卷 13-19页

作者： Jing Zhang Yuan-yue Zhu Lun-hua Deng Yang-qin Chen East China Normal University and department of physics state key laboratory of precision spectroscopy

The Doppler-limited absorption spectrum of16O2+cation was observed in the region of11385-12100 cm-1by optical heterodyne velocity modulation absorption spectroscopy(OH-VMS). The transitions were assigned to the(2, 19),(3, 20), and(5, 21) bands in the second negative system(A2Πu-X2Πg). All the available lines measured using OH-VMS were global fitted in a nonlinear least-squares fitting procedure, and precise molecular constants(Bv, Av, Dv, pv, qv, γv) were obtained for the involved levels.

关键词： Absorption spectra Absorption spectroscopy Optical absorption Spectrum analysis

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Frequency stabilization of a 399-nm laser by modulation transfer spectroscopy in an ytterbium hollow cathode lamp

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Chinese physics B 2011年第1期20卷 310-315页

作者：王文丽叶捷蒋海灵毕志毅马龙生徐信业 state key laboratory of precision spectroscopy and department of physics East China Normal University

The modulation transfer spectroscopy in an ytterbium hollow cathode lamp at 399 nm is measured. The error signal for frequency locking is optimized by measuring the dependences of its slope, linewidth and magnitude on various parameters. Under the optimum condition, the laser frequency at 399 nm can be stabilized. The long-term stability of laser frequency is measured by monitoring the fluorescence signal of the ytterbium atomic beam induced by the locked laser. The laser frequency is shown to be tightly locked, and the stabilized laser is successfully applied to the cooling of ytterbium atoms.

关键词： laser frequency stabilization modulation transfer spectroscopy ytterbium hollow cathode lamp

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Clock-transition spectrum of ^(171)Yb atoms in a one-dimensional optical lattice

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Chinese physics B 2013年第9期22卷 342-347页

作者：陈宁周敏陈海琴方苏黄良玉张晓航高琪蒋燕义毕志毅马龙生徐信业 state key laboratory of precision spectroscopy and department of physics East China Normal University

An optical atomic clock with 171yb atoms is devised and tested. By using a two-stage Doppler cooling technique, the 171Yb atoms are cooled down to a temperature of 6 ± 3 μK, which is close to the Doppler limit. Then, the cold 171Yb atoms are loaded into a one-dimensional optical lattice with a wavelength of 759 nm in the Lamb-Dicke regime. Furthermore, these cold 171yb atoms are excited from the ground-state 1S0 to the excited-state 3P0 by a clock laser with a wavelength of 578 nm. Finally, the 1S0-3P0 clock-transition spectrum of these 171yb atoms is obtained by measuring the dependence of the population of the ground-state 1 S0 upon the clock-laser detuning.

关键词： optical lattice clocks laser cooling and trapping ytterbium clock-transition spectrum

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Propagation properties of electromagnetic fields in elliptic dielectric hollow fibres and their applications

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Chinese physics B 2010年第8期19卷 325-337页

作者：李会容印建平 state key laboratory of precision spectroscopy Department of PhysicsEast China Normal University

We numerically calculate and analyse the electromagnetic fields, optical intensity distributions, polarization states and orbital angular momentum of some elliptic hollow modes in an elliptic dielectric hollow fiber （EDHF） by using Mathieu functions, and also calculate the optical potential of the blue-detuned eHE11 mode evanescent-light wave for ^85Rb atoms, including the position-dependent van der Waals potential, and discuss briefly some potential applications of our EDHF in atom and molecule optics, etc. Our study shows that the vector electric field distributions of the odd modes in the cross section of the EDHF are the same as that of the even modes and with different boundary ellipses by rotating an angle of π/2, and the orbital angular momentum （OAM） of single HE （EH） mode is exactly equal to zero, while that of dual-mode in the EDHF is fractional in h, and has a sinusoidal oscillation as z varies. The EDHF can be used to produce various elliptic hollow beams, even to generate and study various atomic vortices with a fractional charge and its fractional quantum Hall effect in atomic Bose Einstein condensate, and so on.

关键词： elliDtic hollow modes optical potential orbital angular momentum polarisation

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A novel method to measure the isotope shifts and hyperfine splittings of all ytterbium isotopes for a 399-nm transition

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Chinese physics B 2010年第12期19卷 174-180页

作者：王文丽徐信业 state key laboratory of precision spectroscopy and department of physics East China Normal University

We report the experimental results on measuring the isotope shifts and hyperfine splittings of all ytterbium isotopes for a 399-nm transition by using a quite simple and novel method. It benefits from the advantages of the modulation transfer spectroscopy in an ytterbium hollow cathode lamp and the Doppler-free spectroscopy in a collimated ytterbium atomic beam. The key technique in this experiment is simultaneously measuring the frequency separations of the two spectra twice, and the separation difference between two measurements is solely determined by the well-defined frequency of an acousto-optics modulator. Compared with the most of previously reported experimental results, ours are more accurate and completed, which will provide the useful information for developing a more accurate theoretical model to describe the interaction inside an ytterbium atom.

关键词： isotope shift hyperfine splitting modulation transfer spectroscopy ytterbium

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Analysis of the blackbody-radiation shift in an ytterbium optical lattice clock

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Chinese physics B 2016年第10期25卷 119-127页

作者：徐艺琳徐信业 state key laboratory of precision spectroscopy and department of physics East China Normal University

We accurately evaluate the blackbody-radiation shift in a171 Yb optical lattice clock by utilizing temperature measurement and numerical simulation. In this work. three main radiation sources are considered for the blackbody-radiation shift, including the heated atomic oven, the warm vacuum chamber, and the room-temperature vacuum windows. The temperatures on the outer surface of the vacuum chamber are measured during the clock operation period by utilizing seven calibrated temperature sensors. Then we infer the temperature distribution inside the vacuum chamber by numerical simulation according to the measured temperatures. Furthermore, we simulate the temperature variation around the cold atoms while the environmental temperature is fluctuating. Finally, we obtain that the total blackbody-radiation shift is -1.289（7）Hz with an uncertainty of 1.25×10;for our;Yb optical lattice clock. The presented method is quite suitable for accurately evaluating the blackbody-radiation shift of the optical lattice clock in the case of lacking the sensors inside the vacuum chamber.

关键词： optical lattices blackbody radiation shift temperature measurement finite element analysis

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Deceleration of a continuous-wave (CW) molecular beam with a single quasi-CW semi-Gaussian laser beam

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Chinese physics B 2008年第10期17卷 3672-3677页

作者：尹亚玲夏勇印建平 state key laboratory of precision spectroscopy Department of PhysicsEast China Normal University

We propose a promising scheme to decelerate a CW molecular beam by using a red-detuned quasi-cw semi-Gaussian laser beam （SGB）. We study the dynamical process of the deceleration for a CW deuterated ammonia （ND3） molecular beam by Monte-Carlo simulation method. Our study shows that we can obtain a ND3 molecular beam with a relative average kinetic energy loss of about 10% and a relative output molecular number of more than 90% by using a single quasi-cw SGB with a power of 1.5kW and a maximum optical well depth of 7.33mK.

关键词： optical Stark deceleration semi-Gaussian beam

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Production of CH(A^2△) by multi-photon dissociation of (CH_3)_2CO, CH_3NO_2, CH_2Br_2, and CHBr_3 at 213 nm

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Chinese physics B 2014年第8期23卷 327-332页

作者：李胜强许亮陈扬骎邓联忠印建平 state key laboratory of precision spectroscopy Department of Physics East China Normal University

In order to realize electrostatic Stark deceleration of CH radicals and study cold chemistry, the fifth harmonic of a YAG laser is used to prepare CH （A2△） molecules through using the multi-photon dissociation of （CH3）eCO, CH3NO2, CHzBr2, and CHBr3 at ~ 213 nm. The CH product intensity is measured by using the emission spectrum of CH （A2△→XeH）. The dependence of fluorescence intensity on laser power is studied, and the probable dissociation channels are analyzed. The relationship between the fluorescence intensity and some parameters, such as the temperature of the beam source, stagnation pressure, and the time delay between the opening of pulse valve and the photolysis laser, are also studied. The influence of three different carrier gases on CH signal intensity is investigated. The vibrational and rotational temperatures of the CH （Ae△） product are obtained by comparing experimental data with the simulated ones from the LIFBASE program.

关键词： fifth harmonic of YAG laser photodissociation emission spectrum

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Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

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Chinese physics B 2014年第12期23卷 148-154页

作者：李胜强许亮夏勇汪海玲印建平 state key laboratory of precision spectroscopy Department of Physics East China Normal University

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.

关键词： controllable high-efficiency surface trap cold polar molecules

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