排序方式: 共有22条查询结果,搜索用时 31 毫秒
1.
2.
Damage threshold of crystals SiO2 and YAG against 60-900 fs, 800 nm laser pulses are reported. The breakdown mechanisms were discussed based on the double-flux model and Keldysh theory. We found that impact ionization plays the important role in the femtosecond laser-induced damage in crystalline SiO2, while the roles of photoionization and impact ionization in YAG crystals depend on the laser pulse durations. 相似文献
3.
Tianqing Jia Motoyoshi Baba Fuli Zhao Xiaojun Wu Masayuki Suzuki Zhizhan Xu 《Solid State Communications》2007,141(11):635-638
We present a simple route for ZnSe nanowire growth in the ablation crater on a ZnSe crystal surface. The crystal wafer, which was horizontally dipped in pure water, was irradiated by femtosecond laser pulses. No furnace, vacuum chamber or any metal catalyst were used in this experiment. The size of the nanowires is about 1-3 μm long and 50-150 nm in diameter. The growth rate is 1-3 μm/s, which is much higher than that achieved with molecular-beam epitaxy and chemical vapor deposition methods. Our discovery reveals a rapid and simple way to grow nanowires on designed micro-patterns, which may have potential applications in microscopic optoelectronics. 相似文献
4.
5.
Fethi SOLTANI 《数学研究及应用》2015,35(4):425-434
We define and study the Fourier-Wigner transform associated with the Dunkl operators,and we prove for this transform an inversion formula.Next,we introduce and study the Weyl transforms W_σ associated with the Dunkl operators,where cr is a symbol in the Schwartz space S(R~d×R~d).An integral relation between the precedent Weyl and Wigner transforms is given.At last,we give criteria in terms of σ for boundedness and compactness of the transform W_σ. 相似文献
6.
Photochemical studies on the use of chiral metal complexes in homogenous and heterogeneous systems are surveyed and commented on their significance. A main focus is laid on the utility of the ΔΛ isomerism of octahedral metal complexes as a chiral source. The reported works demonstrate that chiral metal complexes are effective as a molecular element in achieving varieties of functions such as chiral discrimination, chiral transfer, sensing and photoresponsive guests for biomolecules or liquid crystals. 相似文献
7.
Single-shot laser damage threshold of MgO for 40-986 fs, 800 nm laser pulses is reported. The pump-probe measurements with femtosecond pulses were carried out to investigate the time-resolved electronic excitation processes. A theoretical model including conduction band electrons (CBE) production and laser energy deposition was applied to discuss the roles of multiphoton ionization (MPI) and avalanche ionization in femtosecond laser-induced dielectric breakdown. The results indicate that avalanche ionization plays the dominant role in the femtosecond laser-induced breakdown in MgO near the damage threshold. 相似文献
8.
Haiyi Sun Tianqing Jia Xiaoxi Li Donghai Feng Xiaochun Ge 《Applied Surface Science》2006,252(14):5109-5115
We have investigated the damage for ZrO2/SiO2 800 nm 45° high-reflection mirror with femtosecond pulses. The damage morphologies and the evolution of ablation crater depths with laser fluences are dramatically different from that with pulse longer than a few tens of picoseconds. The ablation in multilayers occurs layer by layer, and not continuously as in the case of bulk single crystalline or amorphous materials. The weak point in damage is the interface between two layers. We also report its single-short damage thresholds for pulse durations ranging from 50 to 900 fs, which departs from the diffusion-dominated scaling. A developed avalanche model, including the production of conduction band electrons (CBE) and laser energy deposition, is applied to study the damage mechanisms. The theoretical results agree well with our measurements. 相似文献
9.
10.
In this work we consider the satellite version of the restricted three-body problem when masses of the primary bodies P0, P1 vary isotropically with different rates, and their total mass changes according to the joint Meshcherskii law. Equations of motion of the body P2 of infinitesimal mass are obtained in terms of the osculating elements of the aperiodic quasi-conical motion about the body P0. Doubly averaging these equations and using the Hill approximation, we have obtained the differential equations determining the secular perturbations of the orbital elements and determined the domains of possible values of the system parameters for which their analytical solutions are expressed in terms of elementary or elliptic functions. The bodies P0, P1 mass variation laws for which the corresponding differential equations are integrable, have been found. 相似文献