摘要：
We demonstrate an efficient scheme for controlling the tunneling ionization of a H2+ molecular ion. Our scheme is based on the idea that the tunneling ionization rate is highly dependent on the instantaneous magnitude of the electric field. By manipulating the relative phase of the synthesized 5-fs, 790–395-nm laser field, the fragments yielded by the tunneling ionization show a large asymmetry relative to the laser polarization. We find that the time-dependent ionization rate is sharply peaked near the antinodes of the synthesized field. Most importantly, the critical internuclear distances at which the tunneling ionization rate is enhanced depend on the field strength of the antinodes. It is well explained by tracing the laser-driven motion of the electron in the field-dressed double well potential.
作者机构：
[Lu, Xingqiang] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Hunan, Peoples R China.;[Guo, Wei] Univ South China, Sch Elect Engineer, Hengyang 421001, Hunan, Peoples R China.;[Lu, Xingqiang] Univ South China, Sch Nucl Sci & Technol, 28 Changsheng West Rd, Hengyang 421001, Hunan, Peoples R China.
会议名称：
International Conference on Electronic and Electrical Engineering (CEEE)
会议时间：
MAY 16-18, 2014
会议地点：
Lushan, PEOPLES R CHINA
会议主办单位：
[Lu, Xingqiang] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Hunan, Peoples R China.^[Guo, Wei] Univ South China, Sch Elect Engineer, Hengyang 421001, Hunan, Peoples R China.
摘要：
We present an experimental method to calibrate the peak intensities of femtosecond laser pulses at 410 nm by multiphoton ionization of Xe using photoelectron imaging technique. The photoelectron kinetic energies and angular distributions at different laser intensities are obtained from the measured photoelectron images. By linear fitting the energy data, based upon the ponderomotive model, the calibration coefficient of pulse peak intensity is thus obtained. The energy designation of the Rydberg states from the calibrated laser intensities accord well to the angular distributions designation. The two ionization energies of xenon (ionized into P-2(3/2) and P-2(1/2) respectively), obtained by this method, are quite accurate, compared with the values provided by other methods. The wavelength effect to this experimental method is discussed.
摘要：
3D finite-difference time-domain method (FDTD) is carried out to simulate femtosecond optical pulses incident on silver film perforated by subwavelength holes arrays. Both square arrays and hexagonal arrays of nanoholes in silver film are considered. It is found that optical transmittance of square arrays almost does not vary with the polarization direction of incident light, while optical transmittance of hexagonal arrays varies obviously, especially when the wavelength equals the periodicity of holes arrays. This will be important for applications of novel optical devices.
摘要：
Heating of ions by two Alfvén waves propagating along an external magnetic field via nonresonant wave-particle interaction in low-β plasmas is studied using test-particle simulation. Due to subcyclotron ion resonance, the heating effect of the left-hand polarized Alfvén wave pair is 10% greater than that of the right-hand polarized pair. The results show that the perpendicular and parallel (to the external magnetic field) temperatures, as well as the parallel fluid velocity, vary sinusoidally with the phase difference. Furthermore, the magnitude of the oscillations decreases with the ratio of the frequencies of the two waves. When the frequency ratio reaches above 2, the effect of the phase difference vanishes.
作者：
Guo, Wei*;Wei, Shanshan;Lu, Xingqiang;Wang, Li
期刊：
Bulletin of the Korean Chemical Society,2010年31(12):3693-3696 ISSN：1229-5949
通讯作者：
Guo, Wei
作者机构：
[Guo, Wei; Wei, Shanshan] Univ S China, Sch Elect Engn, Hengyang 421001, Peoples R China.;[Lu, Xingqiang] Univ S China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Wang, Li] Dalian Inst Chem Phys, State Key Lab Mol React Dynam, Dalian 116023, Peoples R China.
通讯机构：
[Guo, Wei] U;Univ S China, Sch Elect Engn, Hengyang 421001, Peoples R China.
关键词：
Two-step model;Rydberg states;Ponderomotive potential;Resonant/nonresonant population transfer
摘要：
We experimentally measure the kinetic energy and angular distributions of photoelectrons of N2 as a function of 410 nm femtosecond laser intensity by using velocity map imaging technique. The strong-field multiphoton ionization of molecules shares many of the characteristics with those of atoms. Electron kinetic energies are nearly independent of laser intensities. The independence suggests that the electron peaks in the photoelectron spectrum actually result from a two-step process, indicative of the occurrence of real population in the intermediate states. The relative amplitudes of electron peaks indicate that in the two-step process, nonresonant population transfer dominates for low intensities, while resonant population transfer dominates for higher intensities.
