分子轨道法（PPP—CI）计算芳烃化合物的荧光光谱及激发态结构

应用分子轨道法（ＰＰＰ－ＣＩ）计算了２５种芳烃化合物的基太和第一激发单重态的π电荷分布，偶极矩，键级，以及各分子轨道的能级分布的变化。计算得到的分子吸收光谱波长与实验值非常一致。发现计算得到的荧光辐射能△Ｅｆｌ与荧光光谱波数νｆｌ；计算得到的分子激发过程中的平均键级变化△Ｐ与荧光量子产率△存在如下关系：νｆＬ＝７．０５６０△ＥｆＬ＋２３．３８２０（Ｋｃｍ＾－＾１）ｒ＝０．９８８１ ｌｎФ＝－０．８     

Entropy Theorem for Random Fields on Trees

We study the entropy theorem or the asymptotic equipartition property (AEP)for random fields on bomogeneous trees.A tree is a graph which is connected and contains no circuits. We discuss mainlya homogeneous tree T on which each vertex has N neighboring vertices. T is bipartitegraph because we can partition its vertex set into two equivalence classes, where α～β     

构象最小改变原理

一、前言 Barton在1950年研究甾族化合物等具有刚性构象的稠环化合物时,注意到在椅型构象的环己烷环系上,处于α-键向位的羟基和卤原子等比较活泼,容易发生消除反应等,根据当时     

对北师大編写的中学四年一貫制数学教学大綱初稿的代数部分的意見

我讀了北师大編写的“中学四年一貫制数学教学大綱(初稿)”代数部分,經过一番鉆研,首先使我感觉到这一份代数大綱,具有两个主要优点:1.通过大綱內容的教学,为学生参加工农业生产劳动,提供了必要的代数知識条件,这不但体現了觉中央所提出“教育为无产阶級政治服务,教育与劳动生产結合”的方針,而且为学习其他各門科学与劳动技术打好基础。2.整个大綱精神,貫彻了理論与实际联系的原則,因而在大綱內增添了近似計算、对数計算尺的学习,这些教学內容的实用价值都很大,另外突出地介紹了在生产实际中有广泛应用的运筹学初步这一近代数学知識,并安排了实     

斜抛体的演示

1955年9月人民教育出版社出版的高中物理课本一年级第二分册87节中应用水作斜抛的演示是比较好的一个方法,但是从图中看来这一设计还不够完善,主要的缺点是在科学性方面不够严格,且在演示过程中不易掌握。如在课堂上不能使用很大的储水器,则上面的水位高度就不能保持固定不变。而喷水管口又常随仰角的增大而升高也会影响上下的水位差,且发射点随仰角的变更,也要变更位置,射程就没有较精确的比较标准,没有刻度盘仰角的大小就无法控制。为了克服上述缺点,我把它作了一些改进,现在介绍如下。 (一)器材装置1.用容量一公升的烧瓶一个,里边装满     

物理解题中的另类分解方法——以两道高考题为例

以两道高考题为例,讨论了物理解题中的另类分解方法.     

Measurement of Ultrashort Laser Pulse Width in a Wide Spectrum Range Using Dimethyl Sulfoxide by Optical Kerr Effect Technique

We illustrate that applying the optical Kerr effect technique to dimethyl sulfoxide （DMSO） can determine the width of laser pulses in a wide spectrum range that is transparent. Different from many other simple molecular liquids, such CS2, and toluene, DMSO responds to both 130 fs 800 nm laser pulses and 248 fs 400 nm laser pulses with electronic motions only. Therefore, the observed signal as a function of time reflects the temporal distribution of the intensity. We verify our illustration by both the autocorrelation technique and spectra analysis.     

Near-Field Enhancement and Absorption Properties of Metal-Dielectric-Metal Microcavities in the Mid-Infrared Range

An important property of optical metamaterials is the ability to concentrate light into extremely tiny volumes, so as to enhance their interaction with quantum objects. In this work, we numerically study the near-field en- hancement and absorption properties inside the cylindrical microcavities formed by a Au-GaAs-Au sandwiched structure. At normal incidence, the obtained reflection spectra show that the resonance wavelength of microcav- ities operates in the range of 5-5.S μm. We also calculate the contrast C （C = 1 - Rmln）, which can be increased to 97% by optimizing the structure＇s geometry parameters. Moreover, we demonstrate that the multilayer struc- ture with sub-wavelength electromagnetic confinement allows 10^3-10^4-fold enhancement of the electromagnetic energy density inside the cavities, which contains the most energy of the incident electromagnetic radiation and has a higher quality factor Q, indicating a narrower linewidth for surface enhanced molecular absorption spec- troscopy and the tracking of characteristic molecular vibrational modes in the mid-infrared region. The structure is insensitive to the polarization of the incident wave due to the symmetry of the cylindrical microcavities. The unique properties of the metal-dielectric-metal metamaterials will have potential applications in new plasmonic detectors, bio-sensing and solar cells, etc.