期刊：
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY,2020年231:117800 ISSN：1386-1425
通讯作者：
Guo, Wei
作者机构：
[Guo, Wei; Li, Changming] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Zhou, Panwang; Li, Changming; Tang, Zhe] Shandong Univ, Inst Mol Sci & Engn, Qingdao 266235, Peoples R China.;[Zhou, Panwang] Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Mol React Dynam, Dalian 116023, Peoples R China.
通讯机构：
[Guo, Wei] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
关键词：
Concerted mechanism;Excited state proton transfer;Potential energy surface;Stepwise mechanism;TDDFT
摘要：
Time-dependent density functional theory (TDDFT) method was used to study the different excited states proton transfer mechanism of DPP in cyclohexane (CHE) and Methanol (MeOH). The results indicate that the concerted mechanism and the stepwise mechanism coexist in the double proton transfer process of DPP dimer in the aprotic solvent CHE, the stepwise mechanism predominates. The stepwise mechanism can only carry out single proton transfer (DPP-SFr), the second proton cannot be transferred because it is hindered by high energy barriers. The concerted mechanism produces a double proton transfer (DPP-DPT). The potential energy surface of the DPP dimer was calculated and the double fluorescence phenomenon of DPP dimer observed by Chou et al. (P.T. Chou, Y.I. Liu, H.W. Liu, W.S. Yu. Dual Excitation behavior of double proton transfer versus Charge Transfer in 4-( N-Substituted Amino)-1H-pyrroloi 2.3-bipyridines tuned by dielectric and hydrogen-bonding perturbation, J. Am. Chem. Soc., 123 (2001) 12119-12120) was explained. In view of the protonic solvent effect of methanol, the potential energy curve of the DPP/MeOH cluster was constructed. The fluorescence quenching process of DPP/MeOH clusters was elucidated. The proton transfer pathways of DPP/Me0H clusters are revealed in two different concerted ways (Type A: protons transfer from DPP molecules to Me0H solvent molecules; Type B: protons transfer from MeOH solvent to DPP molecules). The ESPT process of DPP molecules in the protic solvent Me0H was found to be more prone to Type B. The results can help to better understand the intermolecular hydrogen bonding mechanism of DPP molecules. (C) 2019 Elsevier B.V. All rights reserved.
作者机构：
[Guo, Wei; Li, Changming] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Li, Changming] Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Mol React Dynam, Dalian 116023, Peoples R China.;[Zhou, Panwang; Tang, Zhe] Shandong Univ, Inst Mol Sci & Engn, Qingdao 266235, Shandong, Peoples R China.
通讯机构：
[Guo, Wei] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
摘要：
The effects of the heteroatom and position on excited-state intramolecular proton transfer (ESIPT) of 2-[4′-(N-4,6-dichloro-1,3,5-triazi-n-2-yl)2′hydroxyphenyl]benzoxazole (4THBO) have been investigated via time-dependent density functional theory studies. The heteroatoms refer to O and S atoms, and the position effect refers to the N-4,6-trichloro-1,3,5-triazin-2-yl (TCT) substituents in the para and meta positions. The configuration of the four compounds (4THBO, 4THBT, 5THBO and 5THBT) was optimized and the bond lengths, bond angles and infrared spectra of the atoms participating in the proton transfer in the S0 and S1 states were studied. The occurrence of ultrafast ESIPT in the four compounds was demonstrated. Moreover, the potential energy curves of the S0 and S1 states were constructed, and the effects of the heteroatom substitution and substituent position changes on the ESIPT mechanism of the four 4THBO derivatives were analyzed. The results show that the ESIPT barrier of the S atom substitution in the excited state is lower than that of the O atom-substituted molecule, and the energy barrier of the substituent (TCT) in the meta-position is significantly smaller than that in the para-position. These results indicate that the substitution of the S heteroatom promotes the ESIPT of the 4THBO compound and that the substituent (TCT) in the para position is more prone to proton transfer than that in the meta position. Our work could provide a theoretical basis for further experiments.
作者机构：
School of Electrical Engineering,University of South China, Hengyang, 421001;Dalian Institute of Chemical Physics, Chinese Academy of Sciences, State Key Laboratory of Molecular Reaction Dynamics, Dalian, 116023;[郭玮] School of Electrical Engineering,University of South China, Hengyang, 421001 Dalian Institute of Chemical Physics, Chinese Academy of Sciences, State Key Laboratory of Molecular Reaction Dynamics, Dalian, 116023;[常志强; 李月华] School of Electrical Engineering,University of South China, Hengyang, 421001
摘要：
The effect of delay time on photoelectron spectra and state populations of a four-level ladder K2 molecule is investigated by a pump1–pump2–probe pulse via the time-dependent wave packet approach. The periodical motion of the wave packet leads to the periodical change of the photoelectron spectra. The Autler–Townes triple splitting appears at zero delay time, double splitting appears at nonzero delay time between pump1 and pump2 pulses, and no splitting appears at nonzero delay time between pump2 and probe pulses. The periodical change of the state populations with the delay time may be due to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide an important basis for realizing the optical control of molecules experimentally.
作者机构：
School of Electrical Engineering, University of South China, State Key Laboratory of Molecule Reaction Dynamics, Hengyang, 421001;School of Electrical Engineering, University of South China, Hengyang, 421001;[郭玮] School of Electrical Engineering, University of South China, State Key Laboratory of Molecule Reaction Dynamics, Hengyang, 421001;[路兴强] School of Electrical Engineering, University of South China, Hengyang, 421001
作者机构：
[Zhu, Weihua; He, Hongyu; Guo, Wei; Wang, Xinlin; Sheng, Jiabing; Chen, Zhiyong; Wang, XL; Yuan, Zhi] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Wang, Xinlin] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Chen, ZY; Wang, XL; Wang, Xinlin] U;Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
Enhanced optical transmission;Finite-difference time-domain;Localized surface plasmon resonance;Subwavelength metallic film hole arrays;Unit structural features
摘要：
The relation between the enhanced optical transmission and the unit structural features is studied by changing the unit structural features. 3D finite-difference time-domain method is employed to study the enhanced optical transmission of periodic subwavelength circular-sharps shaped hole arrays in metallic films which are deposited on a quartz substrate. The influences of the unit structural features on the enhanced optical transmission are investigated. It is found that the enhanced optical transmission strongly depends on the unit structural edge sharp features: the sharp acuity, numbers, and distributions. The sharp acuity and numbers influence the enhanced optical transmission via localized surface plasmon resonance mode. The sharp distributions affect the enhanced optical transmission equaling to the effect of polarization properties. The results show that the surface plasmons strongly depend on unit structure edge sharp features. Changing the unit structural edge sharp features, the properties of the enhanced optical transmission can be tailored. This paper provides theoretical support for building the various functions of new plasmonic devices.
摘要：
The delay time dependence of photoelectron spectra and state populations of three-level ladder K2 molecule is investigated by pump-probe pulses via time-dependent wave packet approach. The periodical motion of the wave packet with oscillating period 500 fs results in the periodical variation of photoelectron spectra. The photoelectron spectra show Autler-Townes double splitting at zero delay time, and no splitting at positive delay time. The periodical change of state populations with delay time can be ascribed to the coupling effect between the two pulses. It is found that the selectivity of the state populations may be attained by regulating the delay time. The results can provide some important basis for realizing the optical control of molecules experimentally.
作者机构：
[Lu, Xingqiang] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Ma, Zhiwei] Zhejiang Univ, Inst Fus Theory & Simulat, Hangzhou 310027, Zhejiang, Peoples R China.;[Guo, Wei] Univ South China, Sch Elect Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Ma, Zhiwei] Z;Zhejiang Univ, Inst Fus Theory & Simulat, Hangzhou 310027, Zhejiang, Peoples R China.
摘要：
Behavior of the fast earthward flow near the braking region in the magnetotail during a substorm is investigated using the Hall MHD simulation. The results indicate that the highspeed earthward plasma flow is associated with fast reconnection in the middle tail. The fast flow is mainly confined in the range -1.5RE > z > 1.5RE. In the region of -15RE >x >-9RE, due to intermittent magnetic reconnection, the earthward flow exhibits a fluctuating property, i.e., the flow is localized in space and is bursty in time. The pile-up of the magnetic flux and plasma in the near-Earth region leads to formation of the fast-flow braking region or dipolarization front. After colliding into the fast-flow braking region, a part of the Earth flow bounces back, and leads to an intermittent tailward flow in the near-Earth magnetotail.
