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1.
运用含时密度泛函理论和分子动力学相结合的方法, 研究了C5分子线在强激光场中的电离激发.研究发现, 当考虑激光强度对C5分子线激发的影响时, 激光强度越强, 分子吸收的能量越多, 电离也越早, 最终电离的电子也越多, 而且沿激光极化方向的偶极矩的变化及峰值也越大. 关于激光极化方向对C5分子线激发的影响的研究表明, 当激光极化方向沿着C5分子线轴向时, 分子的电离大大增强, x方向的激光脉冲仅能激发起x方向的偶极振荡, 而y方向的激光脉冲仅能激发起y方向的偶极振荡, 而且x方向的激光脉冲激发的偶极振荡强. 研究还表明, 当激光极化方向沿着C5分子线轴向时, 尽管由于电离增强而导致C5分子线C–C键振动的同步性变差, 但在两种激光极化方向情况下, C5分子线的振动模式与中性C5分子线的振动模式相同.
关键词:
含时密度泛函理论
分子动力学
分子电离
碳分子线 相似文献
2.
采用气相扩散方法将C60分子填充到单壁碳纳米管(SWNTs)中,制备出高填充比率的豆荚形纳米材料C60@SWNT,又称为peapod.用金刚石对顶砧(DAC)装置获得高压,在高压下同时利用紫外激光处理样品,通过激光和压力的共同作用研究了C60分子在碳管内的聚合相变.在21.5GPa高压下,同时紫外激光(325nm)照射30min后,拉曼光谱表明C60分子在碳管内发生了聚合,形成一维链状O相聚合结构,且该相变是不可逆的.
关键词:
60 peapod')" href="#">C60 peapod
紫外激光
高压
拉曼光谱 相似文献
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使用532nm,8ns激光脉冲研究了两种新型的基于富勒烯C60结构体系的金纳米粒子合成物的光学非线性.Z-scan实验结果和理论分析的比较表明,材料的非线性吸收强烈地依赖于材料中的配合体,而非线性折射主要来自金纳米粒子的贡献.而且与熟知的C60甲苯溶液光限幅特性作了比较,分析了光限幅机理.
关键词:
60结构体系')" href="#">基于富勒烯C60结构体系
金纳米粒子
等离子体
光限幅 相似文献
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本文采用密度泛涵理论对富勒烯C40分子进行了结构优化,得到了稳定构型,然后构建了以金原子面为电极的电子输运模型.使用非平衡格林函数方法对构建的电子输运模型进行了电子输运性质的计算,得到了电子透射谱和伏安曲线,并分析了分子器件产生电子输运性质的原因.研究结果发现:C40富勒烯的化学活性明显强于富勒烯C60和C32分子,在一些分子能级处,该分子为一个良导体. 相似文献
9.
采用密度泛函理论中的广义梯度近似(generalized gradient approximation,简称GGA),对内掺氢分子富勒烯H2@C60及其二聚体的几何结构和电子结构进行了计算研究.发现无论是在H2@C60单体,还是在其二聚体中,氢倾向以分子形式存在于碳笼中心处,且在室温下氢分子可以做自由旋转.电子结构分析表明,氢分子掺入到C60和C120中,仅对距离费米能级以下-8eV至-5eV能级处有一定的贡献,其他能级的分布和能隙几乎没有变化.
关键词:
几何结构
电子结构
密度泛函 相似文献
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The optical limiting (OL) properties of a novel coordination polymer {[Et4N][Ag2I3]}n with a ladder-like framework were investigated using 532-nm nanosecond laser pulses. The coordination polymer in dimethylformamide solution exhibits better OL performance than C60 in toluene. The results were discussed using a phenomenological model based on excited-state nonlinear absorption. PACS 42.70.Mp; 42.65.-k; 42.70.Hj; 36.20.Hb 相似文献
12.
Optical limiting (OL) properties of two phthalocyanines were investigated by using picosecond laser pulses at 532nm. The relative ratios k of the absorption cross section of the first singlet excited state to that of the ground state were approximately obtained by the analysis of the experimental results in which the reverse saturable absorption model of the three-energy-level scheme was employed. A significant comparison with fullerene C60 was presented for OL. The OL mechanisms have been analysed in detail. 相似文献
13.
The optical-limiting (OL) properties of new palladium nanoparticles based on a C 60 derivative are investigated using nanosecond laser pulses at 532 nm wavelength. The nanoparticles in chloroform solution exhibit better OL performances than C 60in toluene. The main origins concerning the OL are discussed. 相似文献
14.
Optical limiting (OL) properties of CdO nanowires in water and ethanol were investigated by using nanosecond laser pulses at 532 nm. Experimental results show that suspension of CdO nanowires in ethanol exhibits better OL property than solution of C60 in toluene and suspension of CdO nanowires in water. The dominant mechanism for the observed enhanced optical limiting in ethanol suspensions of CdO nanowires is due to nonlinear scattering. 相似文献
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Optical Limiting Properties of Two Soluble Polymer/Multi-Walled Carbon Nanotube Composites 下载免费PDF全文
Two soluble polymer grafted multi-walled carbon nanotubes (MWNTs), including poly(N-vinylcarbazole)-MWNTs and poly(methyl methacrylate)-MWNTs, are synthesized. Their nonlinear optical properties and opticaJ limiting (OL) performances are investigated by z-scan method with 527nm nanosecond laser pulses. These grafted MWNTs dissolved in chloroform show much better optical limiting performance than those of MWNTs and C60 in toluene solution. Nonlinear absorption and nonlinear scattering mechanism are taken into consideration for explaining the observed results. The comparison of the experimental results shows that nonlinear absorption is the dominant mechanism for OL performance of these new samples. 相似文献
16.
H. Wang Y. Zhang H. Tian N. Wang L. Ma P. Yuan 《Applied physics. B, Lasers and optics》2008,92(4):487-491
Recently, many researchers had reported their work about sub- and superluminal propagation. And several experiments had demonstrated
the signal evolution of slow and fast light. In this letter, the authors described a simple experiment for the tracing of
the light signal in saturated absorption (SA) and reverse saturated absorption (RSA) media, firstly. We had, directly, observed
the evolution of slow and fast signals with different waveforms that traveled in a ruby crystal and C60. Through tracking the signal when slow light (v
g
≪
c) and fast light (v
g<0) was observed in a ruby crystal and C60, we concluded that asymmetrical absorption on the periodical signal could account for the generation of slow and fast light
in SA and RSA media. 相似文献
17.
Yundong Zhang Hao Wang Lei Ma Nan Wang He Tian Qiuyun Ouyang Ping Yuan 《Applied physics. B, Lasers and optics》2007,89(2-3):141-143
We experimentally observed negative group velocity in C60 toluene solution at the wavelength of 532 nm for the first time. The observed time advancement of the modulated signal appears
to be due to the RSA (reverse saturable absorption) effect of the C60 molecule. The largest time advancement of 71.65 ms was obtained with a C60 sample of 1.5-mm length with the concentration of 1.39×10-3 mol/l; the corresponding group velocity was -0.021 m/s. We could control the group velocity by adjusting the modulation frequency
and the input intensity.
PACS 42.65.-k; 42.50.Ct; 41.20.Jb 相似文献
18.
C60/PMMA复合材料的反饱和吸收与光限幅特性研究 总被引:1,自引:0,他引:1
本文报导C60/PMMA复合材料的制备方法,并采用调QNd:YAG倍频脉冲激光照射C60/PMMA夏合材料,研究了其反饱和吸收与光限幅将性。在线性透射率为46%条件下,光限幅阈值能量密度为65mJ/cm2,材料破坏能量密度阈值为600mJ/cm2.与C60甲苯溶液相比具有一定的优点。 相似文献
19.
Photofragmentation of the C60 fullerene induced by ultrafast laser pulses is studied by semiclassical dynamics simulation. The simulation study is focused on the excitation below the continuum levels. A laser pulse of 40 fs (FWHM) with an effective photon energy of 2.0 eV and different intensities was selected to interact with the C60 fullerene. The simulation results show that averaged fragmentation size distribution over groups of initial geometries selected at random exhibits a power law pattern with the peak at C2 at high laser pulse intensities. The threshold for the C60 fragmentation was determined. The simulation finds that as many as 55 electrons are excited from the occupied molecular orbitals to unoccupied molecular orbitals upon the laser irradiation and that the number of the fragments significantly depends on the number of electrons excited. Finally, the temperature examination seems to suggest that the nonthermal effect may play a significant role in laser fragmentation of the C60 fullerene. 相似文献
20.
S. Canulescu J. Schou S. F. Nielsen 《Applied Physics A: Materials Science & Processing》2011,104(3):775-780
Thin films of fullerenes (C60) were deposited onto silicon using matrix-assisted pulsed laser evaporation (MAPLE). The deposition was carried out from
a frozen homogeneous dilute solution of C60 in anisole (0.67 wt%), and over a broad range of laser fluences, from 0.15 J/cm2 up to 3.9 J/cm2. MAPLE has been applied for deposition of fullerenes for the first time and we have studied the growth of thin films of solid
C60. The fragmentation of C60 fullerene molecules induced by ns ablation in vacuum of a frozen anisole target with C60 was investigated by matrix-assisted laser desorption/ionization (MALDI). Our findings show that intact fullerene films can
be produced with laser fluences ranging from 0.15 J/cm2 up to 1.5 J/cm2. 相似文献