期刊文献+
共找到467篇文章
< 1 2 24 >
每页显示 20 50 100
Wavelength-and ellipticity-dependent photoelectron spectra from multiphoton ionization of atoms 被引量:1
1
作者 郭珂雨 黎敏 +3 位作者 梁锦台 曹传鹏 周月明 陆培祥 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第2期223-228,共6页
We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Sch... We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state. 展开更多
关键词 multiphoton ionization ultrafast phenomena Freeman resonance
原文传递
Assessing pathological features of breast cancer via the multimodal information of multiphoton and Raman imaging
2
作者 高冰然 陈希文 +4 位作者 张宝萍 Ivan A.Bratchenko 陈建新 王爽 许思源 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第11期151-160,共10页
For unveiling the pathological evolution of breast cancer, nonlinear multiphoton microscopic(MPM) and confocal Raman microspectral imaging(CRMI) techniques were both utilized to address the structural and constitution... For unveiling the pathological evolution of breast cancer, nonlinear multiphoton microscopic(MPM) and confocal Raman microspectral imaging(CRMI) techniques were both utilized to address the structural and constitutional characteristics of healthy(H), ductal carcinoma in situ(DCIS), and invasive ductal carcinoma(IDC) tissues. MPM-based techniques,including two-photon excited fluorescence(TPEF) and second harmonic generation(SHG), visualized label-free and the fine structure of breast tissue. Meanwhile, CRMI not only presented the chemical images of investigated samples with the K-mean cluster analysis method(KCA), but also pictured the distribution of components in the scanned area through univariate imaging. MPM images illustrated that the cancer cells first arranged around the basement membrane of the duct,then proliferated to fill the lumens of the duct, and finally broke through the basement membrane to infiltrate into the stroma.Although the Raman imaging failed to visualize the cell structure with high resolution, it explained spectroscopically the gradual increase of nucleic acid and protein components inside the ducts as cancer cells proliferated, and displayed the distribution pattern of each biological component during the evolution of breast cancer. Thus, the combination of MPM and CRMI provided new insights into the on-site pathological diagnosis of malignant breast cancer, also ensured technical support for the development of multimodal optical imaging techniques for precise histopathological analysis. 展开更多
关键词 nonlinear multiphoton microscopic imaging Raman microspectral imaging breast cancer
原文传递
Multiphoton microscopy for tumor regression grading after neoadjuvant treatment for colorectal carcinoma 被引量:2
3
作者 Lian-Huang Li Zhi-Fen Chen +5 位作者 Xing-Fu Wang Shuang-Mu Zhuo Hong-Sheng Li Wei-Zhong Jiang Guo-Xian Guan Jian-Xin Chen 《World Journal of Gastroenterology》 SCIE CAS 2015年第14期4210-4215,共6页
AIM: To evaluate the feasibility of using multiphoton microscopy(MPM) to assess a tumor regression grading(TRG) system.METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radi... AIM: To evaluate the feasibility of using multiphoton microscopy(MPM) to assess a tumor regression grading(TRG) system.METHODS: Fresh specimens from seven patients with colorectal carcinoma undergoing neoadjuvant radiochemotherapy at the Fujian Medical University Union Hospital were obtained immediately after proctectomy.Specimens were serially sectioned(10 μm thickness) and used for MPM or stained with hematoxylin and eosin for comparison.Sections were imaged by MPM using 810 nm excitation, and images were collected in two wavelength channels corresponding to second-harmonic generation(SHG) and two-photon excited fluorescence(TPEF) signals.The ratio of these signal intensities was used to distinguish fibrosis from normal mucosal and serosal tissues.RESULTS: TRG of specimens assessed by MPMwere in complete agreement with histologic grading performed by a consulting pathologist.SHG and TPEF images clearly revealed collagen fibers and fragmented elastic fibers in the muscularis propria specimens following neoadjuvant radiochemotherapy.Additionally, blood vessel hyperplasia was observed as thickening and fibrosis of the intima and media, which was accompanied by minimal inflammatory cell infiltration.Furthermore, the SHG/TPEF ratio in stromal fibrosis(4.15 ± 0.58) was significantly higher than those in the normal submucosal(2.31 ± 0.52) and serosal(1.47 ± 0.10) tissues(P < 0.001 for both).Analysis of emission spectra from cancerous tumor cells revealed two peaks corresponding to nicotinamide adenine dinucleotide hydrogen and flavin adenine dinucleotide signals; the ratio of these values was 1.19 ± 0.02, which is close to a normal metabolic state.CONCLUSION: MPM can be used to perform realtime diagnosis of tumor response after neoadjuvant treatment, and can be applied to evaluate TRG. 展开更多
关键词 multiphoton MICROSCOPY NEOADJUVANT TREATMENT Secon
下载PDF
Study of Microwave Multiphoton Transition of Rydberg Potassium Atom by Using B-Spline 被引量:3
4
作者 JIN Cheng ZHOU Xiao-Xin ZHAO Song-Feng 《Communications in Theoretical Physics》 SCIE CAS CSCD 2005年第6X期1065-1070,共6页
Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical mu... Abstract The B-spline expansion technique and time-dependent two-level approach are applied to study the interaction between the microwave field and potassium atoms in a static electric field. We obtain theoretical multiphoton resonance spectra that can be compared with the experimental data. We also obtain the time evolution of the final state in different microwave fields. 展开更多
关键词 B-SPLINE multiphoton resonance spectra potential model Rabi oscillation
下载PDF
Understanding Tunneling Ionization of Atoms in Laser Fields using the Principle of Multiphoton Absorption 被引量:1
5
作者 Long Xu Li-Bin Fu 《Chinese Physics Letters》 SCIE CAS CSCD 2019年第4期19-23,共5页
The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried... The elaborate energy and momentum spectra of ionized electrons from atoms in laser fields suggest that the ionization dynamics described by tunneling theory should be modified. Although great efforts have been carried out within semiclassical models, there are few discussions describing the multiphoton absorption process within a quantum framework. Comparing the results obtained with the time-dependent Schr?dinger equation(TDSE)and the Keldysh–Faisal–Reiss(KFR) theory, we study the nonperturbative effects of ionization dynamics beyond the KFR theory. The difference in momentum spectra between multiphoton and tunneling regimes is understood in a unified picture with virtual multiphoton absorption processes. For the multiphoton regime, the momentum spectra can be obtained by coherent interference of each periodic contribution. However, the interference of multiphoton absorption peaks will result in a complex structure of virtual multiphoton bands in the tunneling regime. It is shown that the virtual spectra will be almost continuous in the tunneling regime instead of the discrete levels found in the multiphoton regime. Finally, with a model combining the TDSE and the KFR theory,we try to understand the different effects of virtual multiphoton processes on ionization dynamics. 展开更多
关键词 Laser multiphoton ABSORPTION ionized ELECTRONS
原文传递
Multiphoton and tunneling ionization of atoms in an intense laser field 被引量:1
6
作者 付妍卓 赵松峰 周效信 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第11期167-171,共5页
We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods, i.e., the numerical solution of the time-dependent SchrSdinger equation (TDSE), the Perelomov-Popov Ter... We study the ionization probabilities of atoms by a short laser pulse with three different theoretical methods, i.e., the numerical solution of the time-dependent SchrSdinger equation (TDSE), the Perelomov-Popov Terent'ev (PPT) theory, and the Ammosov-Delone-Krainov (ADK) theory. Our results show that laser intensity dependent ionization probabilities of several atoms (i.e., H, He, and Ne) obtained from the PPT theory accord quite well with the TDSE results both in the multiphoton and tunneling ionization regimes, while the ADK results fit well to the TDSE data only in the tunneling ionization regime. Our calculations also show that laser intensity dependent ionization probabilities of a H atom at three different laser wavelengths of 600 nm, 800 nm, and 1200 nm obtained from the PPT theory are also in good agreement with those from the TDSE, while the ADK theory fails to give the wavelength dependence of ionization probability. Only when the laser wavelength is long enough, will the results of ADK be close to those of TDSE. 展开更多
关键词 intense laser field ionization probability multiphoton ionization theory
原文传递
Multiphoton microscopy:An introduction to gastroenterologists 被引量:1
7
作者 Hye Jin Cho Hoon Jai Chun +1 位作者 Eun Sun Kim Bong Rae Cho 《World Journal of Gastroenterology》 SCIE CAS CSCD 2011年第40期4456-4460,共5页
Multiphoton microscopy, relying on the simultaneous absorption of two or more photons by a fluorophore, has come to occupy a prominent place in modern biomedical research with its ability to allow real-time observatio... Multiphoton microscopy, relying on the simultaneous absorption of two or more photons by a fluorophore, has come to occupy a prominent place in modern biomedical research with its ability to allow real-time observation of a single cell and molecules in intact tissues. Multiphoton microscopy exhibits nonlinear optical contrast properties, which can make it possible to provide an exceptionally large depth penetration with less phototoxicity. This system becomes more and more an inspiring tool for a non-invasive imaging system to realize "optical biopsy" and to examine the functions of living cells. In this review, we briefly present the physical principles and properties of multiphoton microscopy as well as the current applications in biological fields. In addition, we address what we see as the future potential of multiphoton microscopy for gastroenterologic research. 展开更多
关键词 multiphoton microscopy Optical biopsy Gastrointestinal disease
下载PDF
Structure of Protonated Heterodimer of Proline and Phenylalanine:Revealed by Infrared Multiphoton Dissociation Spectroscopy and Theoretical Calculations 被引量:1
8
作者 Juan Ren Xian-yi Zhang Xiang-lei Kong 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2020年第5期590-594,I0029-I0038,I0079,共16页
The infrared multiphoton dissociation(IRMPD)spectrum of the protonated heterodimer of Pro Phe H+,in the range of 2700-3700 cm^-1,has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with... The infrared multiphoton dissociation(IRMPD)spectrum of the protonated heterodimer of Pro Phe H+,in the range of 2700-3700 cm^-1,has been obtained with a Fourier-transform ion cyclotron mass spectrometer combined with an IR OPO laser.The experimental spectrum shows one peak at 3565 cm^-1 corresponding to the free carboxyl O-H stretching vibration,and two broad peaks centered at 2935 and 3195 cm^-1.Theoretical calculations were performed on the level of M062 X/6-311++G(d,p).Results show that the most stable isomer is characterized by a charge-solvated structure in which the proton is bound to the unit of proline.Its predicted spectrum is in good agreement with the experimental one,although the coexistence of salt-bridged structures cannot be entirely excluded. 展开更多
关键词 Infrared multiphoton dissociation spectroscopy Mass spectrometry HETERODIMER Amino acids
下载PDF
Highly efficient avalanche multiphoton luminescence from coupled Au nanowires in the visible region 被引量:3
9
作者 WANG Qu-quan (Wuhan University,Wuhan 430072,China) 《功能材料信息》 2007年第5期10-,共1页
We report highly efficient avalanche multiphoton luminescence(MPL)from ordered-arrayed gold nanowires(NWs).The time-average excitation intensity I_(exc) is as low as 5.0-9.1 kW/cm^2.The intensity of avalanche MPL I_(M... We report highly efficient avalanche multiphoton luminescence(MPL)from ordered-arrayed gold nanowires(NWs).The time-average excitation intensity I_(exc) is as low as 5.0-9.1 kW/cm^2.The intensity of avalanche MPL I_(MPL) is about 10~4 times larger than that of three-photon luminescence,the slope ■logI_(MPL)/■logI_(exc) of avalanche MPL reaches as high as 18.3 and the corresponding polarization dependence of I_(MPL) has a form of cos^(50)■_p.The emission dynamics of avalanche MPL and three-photon luminesc... 展开更多
关键词 Au nanowires multiphoton luminescence visible region
下载PDF
Non-perturbative multiphoton excitation studies in an excitonic coupled quantum well system using high-intensity THz laser fields
10
作者 Monica Gambhir Vinod Prasad 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第8期355-363,共9页
Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/AlxGa1-xAs coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity te... Multiphoton excitations and nonlinear optical properties of exciton states in GaAs/AlxGa1-xAs coupled quantum well structure have been theoretically investigated under the influence of a time-varying high-intensity terahertz(THz)laser field.Non-perturbative Floquet theory is employed to solve the time-dependent equation of motion for the laser-driven excitonic quantum well system.The response to the field parameters,such as intensity and frequency of the laser electric field on the state populations,can be used in various optical semiconductor device applications,such as photodetectors,sensors,all-optical switches,and terahertz emitters. 展开更多
关键词 quantum well EXCITONS TERAHERTZ NON-PERTURBATIVE multiphoton laser FLOQUET
原文传递
Photoelectron imaging of resonance-enhanced multiphoton ionization and above-threshold ionization of ammonia molecules in a strong 800-nm laser pulse
11
作者 Le-Le Song Ya-Nan Sun +7 位作者 Yan-Hui Wang Xiao-Chun Wang Lan-Hai He Si-Zuo Luo Wen-Hui Hu Qiu-Nan Tong Da-Jun Ding Fu-Chun Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第6期140-145,共6页
In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photo... In this work, we mainly investigate the NH3 molecular multiphoton ionization process by using the photoelectron velocity map imaging technique. Under the condition of femtosecond laser(wavelength at 800 nm), the photoelectron images are detected. The channel switching and above-threshold ionization(ATI) effect are also confirmed. The kinetic energy spectrum(KES) and the photoelectron angular distributions(PADs) are obtained through the anti-Abel transformation from the original images, and then three ionization channels are confirmed successfully according to the Freeman resonance effect in a relatively low laser intensity region. In the excitation process, the intermediate resonance Rydberg states are C^1 A 1(6 + 2 photons process), B^1 E(6 + 2 photons process) and C^1 A 1(7 + 2 photons process), respectively. At the same time, we also find that the photoelectron angular distributions are independent of laser intensity. In addition, the electrons produced by different processes interfere with each other and they can produce a spider-like structure. We also find ac-Stark movement according to the Stark-shift-induced resonance effect when the laser intensity is relatively high. 展开更多
关键词 PHOTOELECTRON imaging RYDBERG state resonance-enhanced multiphoton IONIZATION PHOTOELECTRON ANGULAR distribution
原文传递
Laser-manipulated the of a harmonically multiphoton transitions trapped particle
12
作者 陈琼 海阔 海文华 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第12期3662-3667,共6页
A single particle magneto-confined in a one-dimensional (1D) quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical inv... A single particle magneto-confined in a one-dimensional (1D) quantum wire experiences a harmonic potential, and imposing a sharply focused laser beam on an appropriate site shapes a δ potential. The theoretical investigation has demonstrated that for a sufficiently strong δ pulse the quantum motional stationary state of the particle is one of the eigenstates of the free harmonic oscillator, and it is determined by the site of the laser beam uniquely, namely a quantum state is admissible if and only if the laser site is one of its nodes. The numerical computation shows that all the nodes of the lower energy states with quantum numbers n ≤ 20, except the coordinate origin, are mutually different. So we can manipulate the multiphoton transitions between the quantum states by adjusting the position of the laser δ pulse and realize the transition from an unknown higher excitation state to a required lower energy state. 展开更多
关键词 quantum wire magnetically trap laser manipulation multiphoton transition
原文传递
Two-colour coherent control of multiphoton ionization: a comparison between long-range and short-range potential model atoms
13
作者 李鹏程 周效信 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第10期2946-2951,共6页
Using the numerical solution of the time-dependent SchrSdinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atom... Using the numerical solution of the time-dependent SchrSdinger equation of a one-dimensional model atom in a two-colour laser field, we have investigated the effects of the potential models on coherent control of atomic multiphoton ionization. It is found that the photoelectron spectra are obviously different for the long-range (Coulomb-like) and short-range (with no excited bound states) potential model atoms, which are produced by two-colour coherent control of atomic multiphoton ionization in a few laser cycles. Our results indicate that two-colour coherent control of atomic multiphoton ionization can be observed in simulations, depending on the choice of the model potentials. 展开更多
关键词 coherent control multiphoton ionization model potential
原文传递
Multiphoton resonant ionization of hydrogen atom exposed to two-colour laser pulses
14
作者 王培杰 方炎 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第10期3668-3671,共4页
This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scann... This paper studies the multiphoton resonant ionization by two-colour laser pulses in the hydrogen atom by solving the time-dependent Schroedinger equation. By fixing the parameters of fundamental laser field and scanning the frequency of second laser field, it finds that the ionization probability shows several resonance peaks and is also much larger than the linear superposition of probabilities by applying two lasers separately. The enhancement of the ionization happens when the system is resonantly pumped to the excited states by absorbing two or more colour photons non-sequentially. 展开更多
关键词 time-dependent Schrodinger equation multiphoton ionization ionization probability
原文传递
Multiphoton ionization of the hydrogen atom exposed to circularly or linearly polarized laser pulses
15
作者 王培杰 何峰 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第12期5291-5295,共5页
This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent SchrSdinger equation. It finds that the ratio of the ioniza... This paper studies the multiphoton ionization of the hydrogen atom exposed to the linearly or circularly polarized laser pulses by solving the time-dependent SchrSdinger equation. It finds that the ratio of the ionization probabilities by linearly and circularly polarized laser pulses varies with the numbers of absorbing photons. With the same laser intensity, the circularly polarized laser pulse favors to ionize the atom with more ease than the linearly polarized laser pulse if only two or three photons are necessary to be absorbed. For the higher order multiphoton ionization, the linearly polarized laser pulse has the advantage over circularly polarized laser pulse to ionize the atom. 展开更多
关键词 time-dependent SchrSdinger equation multiphoton ionization ionization probability
原文传递
The polarization effect of a laser in multiphoton Compton scattering
16
作者 梁国华 吕清正 +1 位作者 滕爱萍 李英骏 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第5期268-276,共9页
The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics (QED) method, which is a non-perturbative theory for the interaction between a plane el... The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics (QED) method, which is a non-perturbative theory for the interaction between a plane electromagnetic field and a charged particle. In order to analyze in the real experimental condition, a Lorentz transformation for the cross section of this process is derived between the laboratory frame and the initial rest frame of electrons. The energy of the scattered photon is analyzed, as well as the cross sections for different laser intensities and polarizations and different electron velocities. The angular distribution of the emitted photon is investigated in a special velocity of the electron, in which for a fixed number of absorbed photons, the electron energy will not change after the scattering in the lab frame. We obtain the conclusion that higher laser intensifies suppress few-laser-photon absorption and enhance more-laser-photon absorption. A comparison between different polarizations is also made, and we find that the linearly polarized laser is more suitable to generate nonlinear Compton scattering. 展开更多
关键词 multiphoton Compton scattering laser-dressed quantum electrodynamics (QED) cross section polarization
原文传递
上一页 1 2 24 下一页 到第
使用帮助 返回顶部