The hydrolysis of 1,2-thiazetidine 1,1-dioxide has been studied by using ab initio and density functional theory at HF/6-31G*, MP2/6-31G* and B3LYP/6-31G* levels, showing there exist two potential theoretical products...The hydrolysis of 1,2-thiazetidine 1,1-dioxide has been studied by using ab initio and density functional theory at HF/6-31G*, MP2/6-31G* and B3LYP/6-31G* levels, showing there exist two potential theoretical products. One is N-ethyl amino-methyl sulfonate (P1) in which breaking of bond S–C is concerted, the other is 2-taurine methyl ester (P2) which involves two reaction processes with two different mechanisms: concerted and stepwise. There are two pathways of a and b in stepwise, and the former is the lowest in energy barrier in the hydrolysis of 1,2-thiazetidine 1,1-dioxide. The energy barriers of water-assisted hydrolysis of 1,2-thiazetidine 1,1-dioxide are obviously lower than those of no-water-assisted hydrolysis. Solvent effects have been considered by means of a polarizable continuum model (PCM).展开更多
We evaluate the impact of temperature on the output behavior of a carbon nanotube field effect transistor （CNFET） based chaotic generator. The sources cause the variations in both current-voltage characteristics of ...We evaluate the impact of temperature on the output behavior of a carbon nanotube field effect transistor （CNFET） based chaotic generator. The sources cause the variations in both current-voltage characteristics of the CNFET device and an overall chaotic circuit is pointed out. To verify the effect of temperature variation on the output dynamics of the chaotic circuit, a simulation is performed by employing the CNFET compact model of Wong et al. in HSPICE with a temperature range from -100℃ to 100℃. The obtained results with time series, frequency spectra, and bifurcation diagram from the simulation demonstrate that temperature plays a significant role in the output dynamics of the CNFET-based chaotic circuit. Thus, temperature-related issues should be taken into account while designing a high-quality chaotic generator with high stability.展开更多
The chemisorption intensities of NH_3 and CO on aluminum clusters A1_n(n=l-13) have been theoretically predicted by using CNDO/2 method and properly selecting the clusters' geometries.The results show that the che...The chemisorption intensities of NH_3 and CO on aluminum clusters A1_n(n=l-13) have been theoretically predicted by using CNDO/2 method and properly selecting the clusters' geometries.The results show that the chemisorptions of NH_3 and GO on Al_2,Al_6 and Al_12 are magically stable and thus are in good agreement with the experimental results.In addition,an electronic structure analysis is made to expound the nature of such a size effect.展开更多
To validate the ability of full configuration interaction quantum Monte Carlo （FCIQMC） for studying the 2D Hubbard model near half-filling regime, the ground state energies of a 4×44×4 square lattice syste...To validate the ability of full configuration interaction quantum Monte Carlo （FCIQMC） for studying the 2D Hubbard model near half-filling regime, the ground state energies of a 4×44×4 square lattice system with various interaction strengths are calculated. It is found that the calculated results are in good agreement with those obtained by exact diagonalization （i.e., the exact values for a given basis set） when the population of psi particles （psips） is higher than the critical population required to correctly sample the ground state wave function. In addition, the variations of the average computational time per 20 Monte Carlo cycles with the coupling strength and the number of processors are also analyzed. The calculated results show that the computational efficiency of an FCIQMC calculation is mainly affected by the total population of psips and the communication between processors. These results can provide useful references for understanding the FCIQMC algorithm, studying the ground state properties of the 2D Hubbard model for the larger system size by the FCIQMC method and using a computational budget as effectively as possible.展开更多
The structure of a zinc（Ⅱ） coordination complex（1）, [C14 H10 N3 O5 Zn1.5]n or [Zn1.5（bzim）（pydc）（H2 O）]n（H2 pydc = pyridine-2,3-dicarboxylic acid, Hbzim = benzimidazole）, has been determined by X-ray crys...The structure of a zinc（Ⅱ） coordination complex（1）, [C14 H10 N3 O5 Zn1.5]n or [Zn1.5（bzim）（pydc）（H2 O）]n（H2 pydc = pyridine-2,3-dicarboxylic acid, Hbzim = benzimidazole）, has been determined by X-ray crystallography and characterized by elemental analysis, IR spectrum and luminescence. Chemical formula： C14 H10 N3 O5 Zn1.5. It crystallizes in the monoclinic system, space group P21/c with a = 12.303（4）, b = 12.052（4）, c = 10.212（3） ？, β = 104.147（4）, V = 1468.3（8） ？3, Z = 4, Mr = 398.30, Dc = 1.802 g/cm3, F（000） = 800, μ = 2.501 mm-1 and S = 1.000. The 2-D network architecture of 1 is constructed from benzimidazole, zinc and pyridine-2,3-dicarboxylic acid. The quantum-chemical calculations have been performed on ‘molecular fragments’ extracted from the crystal structure using the B3 LYP method in Gaussian 09. The luminescence spectrum shows that complex 1 emits blue luminescence.展开更多
45 isomers of TinNm （n ＋ m = 5, 6） clusters, including linear, some planar and some stero configurations, have been predicted by density functional theory method. For five-atom clusters Ti3N2 and Ti2N3, the most st...45 isomers of TinNm （n ＋ m = 5, 6） clusters, including linear, some planar and some stero configurations, have been predicted by density functional theory method. For five-atom clusters Ti3N2 and Ti2N3, the most stable structures are trigonal bipyramid in D3h symmetry, and for TiaN cluster, the isomer with one nitrogen atom occupying the center of quasi-tetrahedron is the most stable. In the isomers of Ti4N2 and Ti3N3, the planar networks are more stable, but for Ti2N4, the six-membered ring configuration is the most favorable. Most linear structures can form weak-strong bonds alternately with higher energy. As regards to planar structures, the more Ti-N bonds are formed, the more stable they will be; for stero closed polyhedral isomers, their energies are lower.展开更多
Finding transition metal catalysts for effective catalytic conversion of CO to CO_(2)has attracted much attention.MXene as a new 2D layered material of early transition metal carbides,nitrides,and carbo-nitrides is a ...Finding transition metal catalysts for effective catalytic conversion of CO to CO_(2)has attracted much attention.MXene as a new 2D layered material of early transition metal carbides,nitrides,and carbo-nitrides is a robust support for achoring metal atoms.In this study,the electronic structure,geometries,thermodynamic stability,and catalytic activity of MXene (Mo_(2)CS_(2)) supported single noble metal atoms (NM=Ru,Rh,Pd,Ir,Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations.First,AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo_(2)CS_(2)monolayer.Three likely reaction pathways,LangmuirHinshelwood (LH),Eley-Rideal (ER),and Termolecular Eley–Rideal (TER) for CO oxidation on the Ru1-and Ir_(1)@Mo_(2)CS_(2)SACs,have been studied in detail.It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions.The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru_(1)-OCO) and formation of OCO-Ir_(1)-OCO intermediate.The downshift d-band center of Ru1-and Ir_(1)@Mo_(2)CS_(2)help to enhance activity and improve catalytst stability.Moreover,a microkinetic study predicts a maximum CO oxidation rate of 4.01×10^(2)s^(-1)and 4.15×10^(3)s^(-1)(298.15K) following the TER pathway for the Ru_(1)-and Ir_(1)@Mo_(2)CS_(2)catalysts,respectively.This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.展开更多
The reaction of acetaldehyde with hydroxyl radical was studied by means of quantum chemical methods. The geometries for all the stationary points on the potential energy surfaces were optimized fully, respectively, a...The reaction of acetaldehyde with hydroxyl radical was studied by means of quantum chemical methods. The geometries for all the stationary points on the potential energy surfaces were optimized fully, respectively, at the G3MP2, G3, and MP2/6-311++G(d,p) levels. Single-point energies of all the species were calculated at the QCISD/6-311++G(d,p) level. The mechanism of the reaction studied was confirmed. The predicted product is acetyl radical that is in agreement with the experiment.展开更多
A population inversion study of GaAs/AlxGa1-xAs three-quantum-well quantum cascade structures is presented. We derive the population inversion condition （PIC） of the active region （AR） and discuss the PICs on diff...A population inversion study of GaAs/AlxGa1-xAs three-quantum-well quantum cascade structures is presented. We derive the population inversion condition （PIC） of the active region （AR） and discuss the PICs on different structures by changing structural parameters such as the widths of quantum wells or barriers in the AR. For some instances, the PIC can be simplified and is proportional to the spontaneous emission lifetime between the second and the first excited states, whereas some other instances imply that the PIC is proportional to the state lifetime of the second excited state.展开更多
MINDO/3 method has been used to study the mechanism of the consecutive addition of HCN to aminoacetonitrile.The results obtained for the first three steps show that the reaction is exothermic,and step I is the rate de...MINDO/3 method has been used to study the mechanism of the consecutive addition of HCN to aminoacetonitrile.The results obtained for the first three steps show that the reaction is exothermic,and step I is the rate determining step.展开更多
The rare-earth elements are generally trivalent,but some,like cerium,praseodymium,and terbium,can also exhibit the tetravalent state.However,tetravalent rare earth(RE)metal-carbonσ-bond complexes remain elusive and h...The rare-earth elements are generally trivalent,but some,like cerium,praseodymium,and terbium,can also exhibit the tetravalent state.However,tetravalent rare earth(RE)metal-carbonσ-bond complexes remain elusive and have not been synthesized without the use of chelating ligands to stabilize them.In contrast,the synthesis of numerous trivalent RE-C bond complexes has been achieved and reported.Herein,we report the first synthesis and structural characterization of a complete series of cerium(IV)alkyl,aryl,and alkynyl complexes without chelate-assisted stabilization.The Ce^(IV)-Cσ-bond complexes are synthesized from reactions of imidazolin-2-iminato cerium(IV)chlorides with lithium alkyl,aryl,or alkynyl reagents,and they have all been characterized by single crystal X-ray diffraction.The investigation of the decomposition of cerium(IV)alkyl complexes shows the generation of alkyl radicals,indicating a homolytic cleavage mechanism of Ce^(IV)-C(sp^(3))σ-bond,which is significantly different from the decomposition mechanism of the REⅢ-C(sp^(3))σ-bond.Quantum theoretical studies were performed to provide insights into the Ce^(IV)-C(sp^(n))(n=1,2,3)σ-bonding properties as well as the high ^(13)C{^(1)H}nuclear magnetic resonance(NMR)chemical shifts of Ce^(IV)-C signals.The electronic influence of the supporting ligands was also studied theoretically,which revealed that the strong electron-donating imidazolin-2-iminato ligand enhanced the energylevel match of the Ce(IV)5d orbitals with the alkyl group.This energy-level match strategy provides insights into the preparation of RE complexes with unusual chemical bonds.展开更多
The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners s...The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners significant attention for its unique properties,including an unconventional charge density wave(CDW)and superconductivity(SC)[2],as well as the interplay between CDW and SC[3].展开更多
Ultrashort laser pulses can serve as fast probes to record instant events.The isolated attosecond pulses(IAPs)generated from high-order harmonic generation(HHG)have been shortened down to about 2 atomic units in time,...Ultrashort laser pulses can serve as fast probes to record instant events.The isolated attosecond pulses(IAPs)generated from high-order harmonic generation(HHG)have been shortened down to about 2 atomic units in time,empowering us to study quantum behaviors of electrons in atoms,molecules,and solids with unprecedented time resolution.Following the cutoff energy law of HHG,the shortest IAP reported so far is driven with short-wavelength infrared(SWIR)pulses,which require additional broadband frequency conversion techniques and raise the bar for attosecond researches.Here,we show that with fewcycle near-infrared(NIR)laser pulses,IAP with pulse duration of 51±4 as is generated during 1-fs linear polarization gate formed by generalized double optical gating(GDOG)technique.The characterization is done with attosecond streak camera,and phase reconstruction is performed with quick phase retrieval by omega oscillation filtering(qPROOF).Furthermore,we show that the IAP generation favors certain carrier envelope phases(CEPs)in the narrow gate,i.e.,IAP is only efficiently produced for certain CEPs,which eliminates the requirement of CEP stabilization.The demonstrated scheme for IAP generation in principle has much higher conversion efficiency than the long-wave driver scheme according to the wavelength scaling law of HHG.Our work suggests an alternative way to generate ultrashort IAPs by applying GDOG on few-cycle free-CEP NIR driving pulses,and is thereby of great importance to facilitate the development of attosecond science and technology.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 20373034)
文摘The hydrolysis of 1,2-thiazetidine 1,1-dioxide has been studied by using ab initio and density functional theory at HF/6-31G*, MP2/6-31G* and B3LYP/6-31G* levels, showing there exist two potential theoretical products. One is N-ethyl amino-methyl sulfonate (P1) in which breaking of bond S–C is concerted, the other is 2-taurine methyl ester (P2) which involves two reaction processes with two different mechanisms: concerted and stepwise. There are two pathways of a and b in stepwise, and the former is the lowest in energy barrier in the hydrolysis of 1,2-thiazetidine 1,1-dioxide. The energy barriers of water-assisted hydrolysis of 1,2-thiazetidine 1,1-dioxide are obviously lower than those of no-water-assisted hydrolysis. Solvent effects have been considered by means of a polarizable continuum model (PCM).
基金Supported by the Basic Science Research Program through the National Research Foundation of Korea Funded by the Ministry of Education,Science and Technology under Grant No 2012-0002777
文摘We evaluate the impact of temperature on the output behavior of a carbon nanotube field effect transistor （CNFET） based chaotic generator. The sources cause the variations in both current-voltage characteristics of the CNFET device and an overall chaotic circuit is pointed out. To verify the effect of temperature variation on the output dynamics of the chaotic circuit, a simulation is performed by employing the CNFET compact model of Wong et al. in HSPICE with a temperature range from -100℃ to 100℃. The obtained results with time series, frequency spectra, and bifurcation diagram from the simulation demonstrate that temperature plays a significant role in the output dynamics of the CNFET-based chaotic circuit. Thus, temperature-related issues should be taken into account while designing a high-quality chaotic generator with high stability.
文摘The chemisorption intensities of NH_3 and CO on aluminum clusters A1_n(n=l-13) have been theoretically predicted by using CNDO/2 method and properly selecting the clusters' geometries.The results show that the chemisorptions of NH_3 and GO on Al_2,Al_6 and Al_12 are magically stable and thus are in good agreement with the experimental results.In addition,an electronic structure analysis is made to expound the nature of such a size effect.
基金Supported by the Natural Science Foundation for Colleges and Universities of Jiangsu Province under Grant No 16KJB140008the National Natural Science Foundation of China under Grant Nos 11447204 and 11647164+1 种基金the Natural Science Foundation of Jiangsu Province under Grant No BK20151079the Scientific Research Foundation of Nanjing Xiaozhuang University under Grant No 2015NXY34
文摘To validate the ability of full configuration interaction quantum Monte Carlo （FCIQMC） for studying the 2D Hubbard model near half-filling regime, the ground state energies of a 4×44×4 square lattice system with various interaction strengths are calculated. It is found that the calculated results are in good agreement with those obtained by exact diagonalization （i.e., the exact values for a given basis set） when the population of psi particles （psips） is higher than the critical population required to correctly sample the ground state wave function. In addition, the variations of the average computational time per 20 Monte Carlo cycles with the coupling strength and the number of processors are also analyzed. The calculated results show that the computational efficiency of an FCIQMC calculation is mainly affected by the total population of psips and the communication between processors. These results can provide useful references for understanding the FCIQMC algorithm, studying the ground state properties of the 2D Hubbard model for the larger system size by the FCIQMC method and using a computational budget as effectively as possible.
基金Supported by the Jilin Province Science and Technology Development Plan Item(No.20140204080GX)the Project of the Education Department of Jilin Province,China(No.JJKH20180777KJ)the Science and Technology Development Projects of Siping City(No.2017057)
文摘The structure of a zinc（Ⅱ） coordination complex（1）, [C14 H10 N3 O5 Zn1.5]n or [Zn1.5（bzim）（pydc）（H2 O）]n（H2 pydc = pyridine-2,3-dicarboxylic acid, Hbzim = benzimidazole）, has been determined by X-ray crystallography and characterized by elemental analysis, IR spectrum and luminescence. Chemical formula： C14 H10 N3 O5 Zn1.5. It crystallizes in the monoclinic system, space group P21/c with a = 12.303（4）, b = 12.052（4）, c = 10.212（3） ？, β = 104.147（4）, V = 1468.3（8） ？3, Z = 4, Mr = 398.30, Dc = 1.802 g/cm3, F（000） = 800, μ = 2.501 mm-1 and S = 1.000. The 2-D network architecture of 1 is constructed from benzimidazole, zinc and pyridine-2,3-dicarboxylic acid. The quantum-chemical calculations have been performed on ‘molecular fragments’ extracted from the crystal structure using the B3 LYP method in Gaussian 09. The luminescence spectrum shows that complex 1 emits blue luminescence.
基金the National Natural Science Foundation of China (No.20503021)Natural Science Foundation of Fujian Province(No.2005HZ01)
文摘45 isomers of TinNm （n ＋ m = 5, 6） clusters, including linear, some planar and some stero configurations, have been predicted by density functional theory method. For five-atom clusters Ti3N2 and Ti2N3, the most stable structures are trigonal bipyramid in D3h symmetry, and for TiaN cluster, the isomer with one nitrogen atom occupying the center of quasi-tetrahedron is the most stable. In the isomers of Ti4N2 and Ti3N3, the planar networks are more stable, but for Ti2N4, the six-membered ring configuration is the most favorable. Most linear structures can form weak-strong bonds alternately with higher energy. As regards to planar structures, the more Ti-N bonds are formed, the more stable they will be; for stero closed polyhedral isomers, their energies are lower.
基金supported by the National Natural Science Foundation of China (Nos. 11874141 and 22033005)the Henan Overseas Expertise Introduction Center for Discipline Innovation (No. CXJD2019005)+1 种基金the Guangdong Provincial Key Laboratory of Catalysis (No. 2020B121201002)funding support from the Researchers Supporting Project number (No. RSP-2021/399), King Saud University, Riyadh, Saudi Arabia。
文摘Finding transition metal catalysts for effective catalytic conversion of CO to CO_(2)has attracted much attention.MXene as a new 2D layered material of early transition metal carbides,nitrides,and carbo-nitrides is a robust support for achoring metal atoms.In this study,the electronic structure,geometries,thermodynamic stability,and catalytic activity of MXene (Mo_(2)CS_(2)) supported single noble metal atoms (NM=Ru,Rh,Pd,Ir,Pt and Au) have been systematically examined using first-principles calculations and ab initio molecular dynamic (AIMD) simulations.First,AIMD simulations and phonon spectra demonstrate the dynamic and thermal stabilities of Mo_(2)CS_(2)monolayer.Three likely reaction pathways,LangmuirHinshelwood (LH),Eley-Rideal (ER),and Termolecular Eley–Rideal (TER) for CO oxidation on the Ru1-and Ir_(1)@Mo_(2)CS_(2)SACs,have been studied in detail.It is found that CO oxidation mainly proceeds via the TER mechanism under mild reaction conditions.The corresponding rate-determining steps are the dissociation of the intermediate (OCO-Ru_(1)-OCO) and formation of OCO-Ir_(1)-OCO intermediate.The downshift d-band center of Ru1-and Ir_(1)@Mo_(2)CS_(2)help to enhance activity and improve catalytst stability.Moreover,a microkinetic study predicts a maximum CO oxidation rate of 4.01×10^(2)s^(-1)and 4.15×10^(3)s^(-1)(298.15K) following the TER pathway for the Ru_(1)-and Ir_(1)@Mo_(2)CS_(2)catalysts,respectively.This work provides guideline for fabricating and designing highly efficient SACs with superb catalyts using MXene materials.
基金Project supported by the Natural Science Foundation of Chongqing of China (No. 2002-7473).
文摘The reaction of acetaldehyde with hydroxyl radical was studied by means of quantum chemical methods. The geometries for all the stationary points on the potential energy surfaces were optimized fully, respectively, at the G3MP2, G3, and MP2/6-311++G(d,p) levels. Single-point energies of all the species were calculated at the QCISD/6-311++G(d,p) level. The mechanism of the reaction studied was confirmed. The predicted product is acetyl radical that is in agreement with the experiment.
基金supported by the National Natural Science Foundation of China(No.60976070)the Special Funds of China Academy of Engineering Physics(No.909)
文摘A population inversion study of GaAs/AlxGa1-xAs three-quantum-well quantum cascade structures is presented. We derive the population inversion condition （PIC） of the active region （AR） and discuss the PICs on different structures by changing structural parameters such as the widths of quantum wells or barriers in the AR. For some instances, the PIC can be simplified and is proportional to the spontaneous emission lifetime between the second and the first excited states, whereas some other instances imply that the PIC is proportional to the state lifetime of the second excited state.
基金Project supported jointly by the National Natural Science Foundation of China and the Natural Science oundation of Jiangxi province
文摘MINDO/3 method has been used to study the mechanism of the consecutive addition of HCN to aminoacetonitrile.The results obtained for the first three steps show that the reaction is exothermic,and step I is the rate determining step.
基金supported by the National Natural Science Foundation of China(grant nos.21890721,21732007,and 22033005)the Shanghai Municipal Committee of Science and Technologysupported by the Xuetang Program of the Department of Chemistry,Tsinghua University。
文摘The rare-earth elements are generally trivalent,but some,like cerium,praseodymium,and terbium,can also exhibit the tetravalent state.However,tetravalent rare earth(RE)metal-carbonσ-bond complexes remain elusive and have not been synthesized without the use of chelating ligands to stabilize them.In contrast,the synthesis of numerous trivalent RE-C bond complexes has been achieved and reported.Herein,we report the first synthesis and structural characterization of a complete series of cerium(IV)alkyl,aryl,and alkynyl complexes without chelate-assisted stabilization.The Ce^(IV)-Cσ-bond complexes are synthesized from reactions of imidazolin-2-iminato cerium(IV)chlorides with lithium alkyl,aryl,or alkynyl reagents,and they have all been characterized by single crystal X-ray diffraction.The investigation of the decomposition of cerium(IV)alkyl complexes shows the generation of alkyl radicals,indicating a homolytic cleavage mechanism of Ce^(IV)-C(sp^(3))σ-bond,which is significantly different from the decomposition mechanism of the REⅢ-C(sp^(3))σ-bond.Quantum theoretical studies were performed to provide insights into the Ce^(IV)-C(sp^(n))(n=1,2,3)σ-bonding properties as well as the high ^(13)C{^(1)H}nuclear magnetic resonance(NMR)chemical shifts of Ce^(IV)-C signals.The electronic influence of the supporting ligands was also studied theoretically,which revealed that the strong electron-donating imidazolin-2-iminato ligand enhanced the energylevel match of the Ce(IV)5d orbitals with the alkyl group.This energy-level match strategy provides insights into the preparation of RE complexes with unusual chemical bonds.
基金support from the National Key R&D Program of China(2021YFA1401800 and 2021YFA1400202)the National Natural Science Foundation of China(12141404)+7 种基金the Natural Science Foundation of Shanghai(22ZR1479700 and 23XD1422200)Shaofeng Duan acknowledged support from the China Postdoctoral Science Foundation(2022M722108)the China National Postdoctoral Program for Innovative Talents(BX20230216)the National Natural Science Foundation of China(12304178)Yanfeng Guo acknowledged the National Key R&D Program of China(2023YFA1406100)the Double First-Class Initiative Fund of ShanghaiTech Universitysupport from the National Key R&D Program of China(2022YFA1402400 and 2021YFA1400100)the National Natural Science Foundation of China(12074248).
文摘The kagome lattice,characterized by its network of cornersharing triangles,provides an excellent platform for studying various novel quantum phenomena.The recently discovered kagome metal AV3Sb5(A=K,Rb,Cs)[1]garners significant attention for its unique properties,including an unconventional charge density wave(CDW)and superconductivity(SC)[2],as well as the interplay between CDW and SC[3].
基金supported by the National Key Research and Development Program of China(grant no.2019YFA0307703)the Major Research Plan of the National Natural Science Foundation of China(grant no.91850201)the National Natural Science Foundation of China(grant nos.12234020 and 11974426).
文摘Ultrashort laser pulses can serve as fast probes to record instant events.The isolated attosecond pulses(IAPs)generated from high-order harmonic generation(HHG)have been shortened down to about 2 atomic units in time,empowering us to study quantum behaviors of electrons in atoms,molecules,and solids with unprecedented time resolution.Following the cutoff energy law of HHG,the shortest IAP reported so far is driven with short-wavelength infrared(SWIR)pulses,which require additional broadband frequency conversion techniques and raise the bar for attosecond researches.Here,we show that with fewcycle near-infrared(NIR)laser pulses,IAP with pulse duration of 51±4 as is generated during 1-fs linear polarization gate formed by generalized double optical gating(GDOG)technique.The characterization is done with attosecond streak camera,and phase reconstruction is performed with quick phase retrieval by omega oscillation filtering(qPROOF).Furthermore,we show that the IAP generation favors certain carrier envelope phases(CEPs)in the narrow gate,i.e.,IAP is only efficiently produced for certain CEPs,which eliminates the requirement of CEP stabilization.The demonstrated scheme for IAP generation in principle has much higher conversion efficiency than the long-wave driver scheme according to the wavelength scaling law of HHG.Our work suggests an alternative way to generate ultrashort IAPs by applying GDOG on few-cycle free-CEP NIR driving pulses,and is thereby of great importance to facilitate the development of attosecond science and technology.
