共查询到20条相似文献,搜索用时 93 毫秒
1.
本文考虑了分子振动非谐性所引起的振动能级之间的费米共振相互作用,利用定态微扰论,从理论上系统地分析了两态和三态之间的费米共振相互作用对能级能量、态函数和谱线强度的影响,在三阶非谐性近似下,得到了计及费米共振相互作用在内的能级能量、态函数和谱线强度的数学解析表达式. 相似文献
2.
用傅立叶变换光谱仪和光学长程装置,记录了CH_2Cl_2分子振动量子数v=1~4的红外吸收光谱(1200~12000 cm~(-1)),归属出CH的伸缩(v_1,v_6)振动和弯曲(v_2)振动和CH_2基团相对于CCl_2基团的摇摆振动(v_8)的泛频和合频能级共47个。考虑了摇摆振动与伸缩和弯曲振动的耦合,使用简正模模型对v_1,v_2,v_6和v_8这四种振动模式的泛频和合频能级进行了拟合,得到了非谐性常数和费米(Fermi)共振和达宁-丹尼生(Darling-Dennison)共振系数。结果表明,摇摆振动与伸缩振动之间的Fermi共振(k_(188)=-254.63 cm~(-1))大于弯曲振动与伸缩振动之间的Fermi共振(k_(122)=-54.87 cm~(-1));伸缩振动之间的Darling-Dennison共振(k_(1166)=-215.28 cm~(-1))大于弯曲振动与摇摆振动之间的Darling-Dennison共振(k_(2288)=-5.72 cm~(-1))。用拟合得到的光谱参数计算出CH_2Cl_2分子的振动能级,与实验数据很好地符合。 相似文献
3.
四氯化碳费米共振的拉曼光谱研究 总被引:1,自引:1,他引:0
费米共振现象是一种广泛存在于分子振动光谱中的现象,特别是结构比较复杂的多原子分子.在多原子分子中当振动倍频或组合频位于某一基频附近,由于发生振动耦合,会出现两个新峰,峰的位置向两侧发生移动,二者谱线强度发生变化,把这种现象称为费米共振.费米共振现象不仅存在于红外光谱中,也存在于拉曼光谱中.文章中测量了CCl4的拉曼光谱,利用所得到的谱线峰位和用Originpro7.5软件程序获得积分强度,用费米共振的相关理论计算了C-Cl的a1对称伸缩振动频率v1与C-Cl2的f对称弯曲振动频率v4的组合频(v1 v4)与(某一未知基频)C-Cl的f对称伸缩振动频率v03的费米共振特征参数,进而计算出了耦合系数W和这一未知基频v03.该文对理解费米共振,了解分子振动频率,研究分子结构有很重要的参考价值. 相似文献
4.
费米共振是分子内和分子间发生的基团间的振动耦合和能量转移现象。有关外场中费米共振的认识、拉曼光谱的研究方法及应用均待开发和推广。本文系统阐述了利用高压DAC技术、变温技术特别是课题组独创的变换溶剂浓度、LCOF等方法获得的有关费米共振的研究成果,即分子场、压力场、温度场等外场对分子内和分子间费米共振的影响:(1)分子场中a.由C_5H_5N在CH_3OH和H_2O中拉曼光谱变化研究表明溶剂效应对费米共振有明显影响;b.通过改变溶液浓度发现了其他方法未能发现的费米共振双线对非对称移动及双线对中倍频的基频亦受费米共振调谐的现象;c.溶液中的氢键、反氢键使分子基团重组而对费米共振产生显著影响;d.C_7H_8和m-C_8H_(105分子间发生会费米共振,且费米共振特性随溶液浓度明显改变;(2)压力场中a.随压强增加谱线蓝移,且频差△随压强改变而引起W改变;b.随压强增加CCl_4在C_6H_6中的v_1+v_4~v_3的W减小速度比纯液体中快,费米共振消失提前。这表明,压强引起的费米共振现象可揭示溶剂效应机理;(3)温度场中温度会影响分子费米共振特性,且对不同分子影响亦不同,温度对CO_2的费米共振影响较大,而对CS_2几乎无影响。本文对分子谱线的认证与归属、分子构象的确定及异构体的鉴别、氢键对分子结构与性质的影响等方面的研究提供了系统的理论与实验依据。 相似文献
5.
在2000 ~ 9000 波数 、 12000 ~12900 波数的光谱区间记录了室温下H2SiCl2气体分子的振动泛频光谱,所用的仪器分别是高分辨傅立叶变换光谱仪和高灵敏激光腔内吸收光谱仪。用局域模模型和包含达林-丹尼生共振的简正模模型,归属了SiH伸缩振动的基频和泛频,振动量子数的改变△VSiH=1, 2, 3, 4 and 6。通过对实验能级的非线性拟合,得到SiH伸缩振动的谐振频率ωm、非谐性常数χm、键间耦合系数λ、莫尔斯振子参数 De、α 和相互作用力常数 。实验发现,随着振动能量的增加,振动簇(manifold,两个SiH键的伸缩振动量子数m+n=常数 )中能量最低的两个能级的间距逐渐减小。当△VSiH≥4时,在实验误差范围内这两个最低的振动态能级简并。这种简并的能级结构类似双原子莫尔斯振子,符合Birge-Sponer 关系。双原子莫尔斯振子直接描述了H2SiCl2分子中SiH 的高泛频伸缩振动,表明在高振动情况下振动能量已经集中到单个SiH键上。 相似文献
6.
7.
费米共振(FR)是一种广泛存在于分子内和分子间的分子振动耦合和能量转移现象。研究了吡啶与乙醇混合溶液中的吡啶分子内费米共振效应(ν1~ν12,ν1+ν6~ν8),发现了吡啶乙醇存在分子间氢键(O—H…N),通过费米共振参数变化和二维相关拉曼光谱(2DCRS)揭示了吡啶乙醇溶液相互作用机理。ν1~ν12,ν1+ν6~ν8通过非谐相互作用引起能量转移,从而导致费米共振参数的变化。2DCRS可以提供更多费米共振信息,阐明了费米双峰的相互作用机制。 相似文献
8.
费米共振现象广泛存在于分子的振动光谱中,如红外光谱、拉曼光谱等。变换浓度方法是光谱分析的一种主要手段。文章中测量了二硫化碳(CS_2)在四氢呋喃(THF)中不同浓度下的拉曼光谱,引入Bertran理论分析研究v_1-2v_2费米共振现象随浓度的变化规律。研究表明,随着二硫化碳体积浓度的降低,溶液中的费米共振特性参数(如光谱强度比、频率间隔、耦合系数、非谐力常数)将随溶剂效应的影响发生明显的变化。例如,光谱强度比逐渐减小,耦合系数逐渐增加等。这些变化不仅受到溶液散射系数的影响,更重要的是弱氢键的形成对振动光谱的影响。光谱图中还出现了拉曼谱线的非对称移动,基频v_1基本没有发生频移,倍频2v_2却逐渐向高波数方向移动,这与理论上的对称移动不相符。通过对分子间微观作用的研究,弱氢键的作用机理可以很好的解释这种现象。这些分析对于进一步研究溶剂效应对费米共振的影响意义重大,对于溶液中的分子振动光谱研究更加具有参考价值。 相似文献
9.
利用拉曼光谱技术测量了CH_3CN和CD_3CN在常温常压下的拉曼光谱,根据微扰理论建立了新的费米共振理论模型,结合同位素替换方法计算了CH_3CN的ν-2~ν_3+ν_4费米共振耦合系数,并且与利用传统Bertran公式计算结果进行了对比。新的费米共振理论模型利用振动能级的跃迁偶极矩实现了费米共振参数的计算,不仅能够计算未发生费米共振时两费米共振双线的初始光谱强度,而且还能够计算两费米共振双线的初始频率。最后,对利用Bertran公式计算获得的结果产生较大误差的原因进行了分析。 相似文献
10.
报道了液态氦温度(4.2 K)下非掺杂ZnSe/BeTe Ⅱ型量子结构中ZnSe势阱层内空间直接光致发光(PL)光谱的磁场依赖性(磁场高达53 T).实验结果显示,随着磁场的增加,激子和带电激子的PL强度呈现出相反的振动行为.当激子的PL强度增加时带电激子的PL强度减小,反之,当激子的强度减小时带电激子的强度却增加.并且在整个磁场范围内,这些振动呈现近似等间隔的周期性变化.这个行为被解释为费米能级与朗道能级的周期性共振,这个共振导致了处于费米能级上的二维电子气态密度的周期性调制.
关键词:
光致发光
二维电子气
带电激子
Ⅱ型量子阱 相似文献
11.
A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques. 相似文献
12.
Herv Cochard 《Comptes Rendus Physique》2006,7(9-10):1018
Sap is transported under tension (i.e. negative pressure) in trees, according to the tension-cohesion theory. Since water is physically instable under negative pressure, a risk of cavitation is possible. Techniques have been developed during the past two decennia to study cavitation in trees. Trees appear remarkably immune to cavitation events. Cavities form only when extreme water stresses occur or when sap freezes. Nucleation is heterogeneous in trees, presumably caused by the aspiration of air bubbles through conduit walls. Threshold xylem pressures for cavitation vary greatly between species, in concordance with the great functional and ecological diversity of trees. To cite this article: H. Cochard, C. R. Physique 7 (2006). 相似文献
13.
S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
14.
A. I. Trokhimets 《Journal of Applied Spectroscopy》1995,62(1):88-90
Institute of Physicoorganic Chemistry, Academy of Sciences of Belarus, 220603, Minsk, Ul. Surganova, 13, Belarus. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 1, pp. 104–107, January–February, 1995. 相似文献
15.
Yepeng Guan 《中国光学快报(英文版)》2008,6(6)
Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate. 相似文献
16.
G. G. Shakhov 《Journal of Applied Spectroscopy》1995,62(3):431-434
S. I. Vavilov State Optical Institute, Russia, 199034, St. Peterburg, Birzhevaya Liniya, 12. Translated from Zhurnal Prikladnoi
Spektroskopii, Vol. 62, No. 3, pp. 38–42, May–June, 1995. 相似文献
17.
Nonlinear optical pulse compression of picosecond pulses typically requires long lengths of optical fiber and multiple components. Periodic structures, such as fiber Bragg gratings, are highly dispersive at wavelengths outside of the photonic bandgap. This implies that such gratings can be used as very short all-fiber compressors. In this paper a number of such compression schemes are reviewed involving uniform and nonuniform fiber Bragg gratings, relying on both soliton and nonsoliton compression principles. Experimental results supporting the corresponding underlying theory are also presented. Finally, an extension of one of the compression schemes is shown, which allows the generation of adjustable high-repetition rate soliton trains. 相似文献
18.
A diode pumped, Q-switched Nd:YAG zigzag slab laser is developed using passive conduction cooling. Flat-flat and unstable resonators are adopted in this experiment. The 150-mJ multi-mode and 100-mJ single-mode laser outputs with pulse width of 10 ns are achieved, corresponding to optical efficiencies of 19% and 13%, respectively. The experimental result demonstrates that the laser has the property of compact structure, high efficiency, reliability, and high beam quality. The design of laser has a potential application in space environment. 相似文献
19.
CUI Xing-Zhu WANG Huan-Yu ZHANG Cheng-Mo CHEN Yong ZHANG Jia-Yu PENG Wen-Xi CAO Xue-Lei LIANG Xiao-Hua WANG Jin-Zhou GAO Min YANG Jia-Wei 《中国物理C(英文版)》2008,32(1)
As the nearest celestial body to the earth, the moon has become a hot spot again in astronomy field recently. The element analysis is a much important subject in many lunar projects. Remote X-ray spectrometry plays an important role in the geochemical exploration of the solar bodies. Because of th equasi-vacuum atmosphere on the moon, which has no absorption of X-ray, the X-ray fluorescence analysis is an effective way to determine the elemental abundance of lunar surface. The CE-1 X-ray fluorescence spectrometer (CE-1/XFS) aims to map the major elemental compositions on the lunar surface. This paper describes a method for quantitative analysis of elemental compositions. A series of ground base experiments are done to examine the capability of XFS. The obtained results, which show a reasonable agreement with the certified values at a 30% uncertainty level for major elements, are presented. 相似文献
20.
N. K. Morozova E. I. Smirnova I. A. Karetnikov O. R. Golovanova V. G. Galstyan V. S. Zimogorskii 《Journal of Applied Spectroscopy》1996,63(4):543-547
Moscow Power Engineering Institute, 14, Krasnokazarmennaya Str., Moscow, GSP, 105835, Russia. Translated from Zhurnal Prikladnois
Spektroskopii, Vol. 63, No. 4, pp. 646–651, July–August, 1996. 相似文献