Field Spectra of Suaeda salsa in Response to Changes of Soil Chemical Properties

[Objective] This study was to investigate the Suaeda salsa community characteristics,further getting the soil chemical properties.[Method] The paired-data of field spectra and corresponding soil physical-chemical property of seventeen samples was used to reveal the relationship between soil chemical property and field spectra（visible and near infra-red spectra）of S.salsa.[Result] The second derivative spectrum of S.salsa at 1 121 nm could reflect the changes of soil organic matter and soil total nitrogen,and that at 1 208 nm could commendably indicate changes of soil total phosphorus and at 724 nm could indicate changes of soil pH.The first derivative spectrum of S.salsa at 353 nm can indicate changes of soil available potassium,and that at 950 nm could commendably reflect the changes of soil salt content.[Conclusion] Our results laid basis for monitoring chemical property of soil covered with S.salsa using remote sensing technology.

Evaluation of polarization field in InGaN/GaN multiple quantum well structures by using electroluminescence spectra shift

In order to investigate the inherent polarization intensity in InGaN/GaN multiple quantum well(MQW) structures,the electroluminescence(EL) spectra of three samples with different GaN barrier thicknesses of 21.3 nm, 11.4 nm, and 6.5 nm are experimentally studied. All of the EL spectra present a similar blue-shift under the low-level current injection,and then turns to a red-shift tendency when the current increases to a specific value, which is defined as the turning point.The value of this turning point differs from one another for the three InGaN/GaN MQW samples. Sample A, which has the GaN barrier thickness of 21.3 nm, shows the highest current injection level at the turning point as well as the largest value of blue-shift. It indicates that sample A has the maximum intensity of the polarization field. The red-shift of the EL spectra results from the vertical electron leakage in InGaN/GaN MQWs and the corresponding self-heating effect under the high-level current injection. As a result, it is an effective approach to evaluate the polarization field in the InGaN/GaN MQW structures by using the injection current level at the turning point and the blue-shift of the EL spectra profiles.

Molecular Spectra and Dissociation Dynamics of Oxalyl Chloride: Effect of External Electrical Fields

Oxalyl chloride is a highly toxic and caustic substance, which widely exists in human production and life as a kind of volatile organic compound. Based on the density functional theory B3 LYP at 6-311++G(d, p) level, the influences of external electric field on the bond length, bond energy, dipole moment and dissociation mechanism are optimized. The results indicate that the C_1–Cl_3 bond length increases while the C_4–Cl_6 bond decreases. At the same time, the carbon-carbon bond length gradually increases with the increase of electric field. The total energy decreases while the dipole moment gradually increases with the increase of electric field. In the infrared spectra, the vibration frequency of the carbon-chlorine(C_4–Cl_6) bond decreases while the vibration frequency of the carbon-oxygen bond increases. In the ultraviolet-visible spectra, the wavelength of the strongest absorption peak increases as the external electric field increases and shows an observable red shift phenomenon. Additionally, single point energies of oxalyl chloride along the carbon-carbon bond are scanned with the equation-of-motion coupled cluster method restricted to single and double excitations(EOM-CCSD) method and the potential energy curves under different external electric fields are obtained. The dissociation barrier in potential energy curve decreases because of the breakage of carbon-carbon bond with the increase of external electric field. These results provide reference for further researches on the properties of oxalyl chloride and offer a theoretical basis for the study of oxalyl chloride degradation.

Study on the Physical and Dissociation Properties of Disulfur Dichloride under Electric Fields

Disulfur dichloride is a hazardous substance, which is irritating to the eyes. It is significant to study the physical and dissociation properties under external electric fields. The bond length, energy, dipole moment, orbital energy level distribution, infrared spectra and dissociation properties of disulfur dichloride molecule under different external fields are obtained by using the density functional theory at the B3LYP/6-311++G(d, p) basis set level. In addition, ultraviolet-visible absorption spectra of the molecule in different electric fields are studied with configuration interaction-single excitation(CIS)/6-311++G(d, p) method. According to the results, it has been found that as the electric field exerted along the positive direction of the z-axis increases, the two sulfur-chlorine(S-Cl) bond lengths become longer and tend to break, while the sulfur-sulfur(S-S) bond length becomes shorter and the energy gap decreases. The infrared spectrum and ultraviolet-visible absorption spectra both exhibit red shift under electric field. Moreover, by scanning the potential energy surface of disulfur dichloride about S-Cl bond, the dissociation barrier decreases with the increase of positive electric field. When the external electric field arrives at 0.040 atomic units, the barrier disappears, meaning the dissociation of disulfur dichloride. The present results offer an important reference to further study of disulfur dichloride.

Excitonic Absorption of Semiconductor Nanorings under Terahertz Fields

The optical absorption of GaAs nanorings （NRs） under adc electric field and a terahertz （THz） ac electric field applied in the plane containing the NRs is investigated theoretically. The NRs may enclose some magnetic flux in the presence of a magnetic field perpendicular to the NRs plane. Numerical calculation shows that the excitonic effects are essential to correctly describe the optical absorption in NRs. The applied lateral THz electric field, as well as the dc field leads to reduction, broadening and splitting of the exciton peak. In contrast to the presence of a dc field, significant optical absorption peak arises below the zero-field bandgap in the presence ofa THz electric field at a certain frequency. The optical absorption spectrum depends evidently on the frequency and amplitude of the applied THz field and on the magnetic flux threading the NRs. This promises potential applications of NRs for magneto-optical and THz electro-optical sensing.

Nearshore Wave Field Analysis Using SAR Images

Satellite remote sensing technique offers a wide range of information, and is one of the tools for ocean wave observation. This paper discusses the limitations of Synthetic Aperture Radar (SAR) images in wave field analysis. It is found that the wave field analysis is affected by the gray value distribution of image and the relationship between satellite travel and wave propagation directions. Since human activities and coastal engineering are performed in nearshore areas, some issues are discussed for nearshore SAR image analysis. Several case studies show that the wave parameters estimated from nearshore SAR images are quite different from in situ measurements, suggesting that the wave information derived from nearshore SAR images cannot appropriately represent the wave characteristics. One of the reasons is that the wave field is non homogeneous in the nearshore area.

The dissociation pathways of N_2^+ in intense femtosecond laser fields

Using a neutral N2 beam as target, this paper studies the dissociation of N2^＋ in intense femtosecond laser fields （45 fs, ～ 1 × 10^16 W/cm^2） at the laser wavelength of 800 nm based on the time-of-flight mass spectra of N＋ fragment ions. The angular distributions of N^＋ and the laser power dependence of N^＋ yielded from different dissociation pathways show that the dissociation mechanisms mainly proceed through the couplings between the metastable states （A, B and C） and the upper excited states of N^＋.A coupling model of light-dressed potential energy curves of N2^＋ is used to interpret the kinetic energy release of N^＋.

Manifestation of external field effect in time-resolved photo-dissociation dynamics of LiF

The photo-dissociation dynamics of LiF is investigated with newly constructed accurate ab initio potential energy curves （PECs） using the time-dependent quantum wave packet method. The oscillations and decay of the wave packet on the adiabats as a function of time are given, which can be compared with the femtosecond transition-state （FTS） spectroscopy. The photo-absorption spectra and the kinetic-energy distribution of the dissociation fragments, which can exhibit the vibration-level structure and the dispersion of the wave packet, respectively, are also obtained. The investigation shows a blue shift of the band center for the photo-absorption spectrum and multiple peaks in the kinetic-energy spectrum with increasing laser intensity, which can be attributed to external field effects. By analyzing the oscillations of the wave packet evolving on the upper adiabat, an approximate inversion scheme is devised to roughly deduce its shape.

Singlet-Triplet Transition in Quantum Dots Confined by Triangular and Bowl-Like Potentials： the Effect of Electric Fields

We theoretically investigate the energy spectra of two-electron two-dimensional （2e 2D） quantum dots （QDs） confined by triangular potentials and bowl-like potentials in a magnetic field by exact diagonalization in the framework of effective mass theory. An in-plane electric field is found to contribute to the singlet-triplet transition of the ground state of the 2e 2D QDs confined by triangular or bowl-like potentials in a perpendicular magnetic field. The stronger the in-plane electric field, the smaller the magnetic field for the total spin of the ground states in the dot systems to change from S = 0 to S = 1. However, the influence of an in-plane electric field on the singlettriplet transition of the ground state of two electrons in a triangular QD modulated by a perpendicular magnetic field is quite small because the triangular potential just deviates from the harmonic potential well slightly. We find that the strength of the perpendicular magnetic field needed for the spin singlet-triplet transition of the ground state of the QD confined by a bowl-like potential is reduced drastically by applying an in-plane electric field.

Photodetachment of H^- in a Static Electric Field near a Surface

The photodetachment of H^- in a static electric field near a surface is investigated based on the closed orbit theory. It is found the distance between the ion and the surface modulates the cross section of photodetachment. For an elastic surface perpendicular to electric field, the detachment spectrum displays a staircase structure, in contrast with the smooth oscillation when only the electric field exists.

On the Spectra of General Ordinary Quasi-Differential Operators and Their L2w-Solutions

In this paper, we consider the general ordinary quasi-differential expression τ of order n with complex coefficients and its formal adjoint τ+ on the interval [a,b). We shall show in the case of one singular end-point and under suitable conditions that all solutions of a general ordinary quasi-differential equation are in the weighted Hilbert space provided that all solutions of the equations and its adjoint are in . Also, a number of results concerning the location of the point spectra and regularity fields of the operators generated by such expressions may be obtained. Some of these results are extensions or generalizations of those in the symmetric case, while the others are new.

Structural deformation of nitro group of nitromethane molecule in liquid phase in an intense femtosecond laser field

The structural deformation of NO2 group induced by an intense femtosecond laser field of liquid nitromethane（NM）molecule is detected by time-and frequency-resolved coherent anti-Stokes Raman spectroscopy（CARS） technique with the intense pump laser. Here, we present the mechanism of molecular alignment and deformation. The CARS spectra and its FFT spectra of liquid NM show that the NO2 torsional mode couples with the CN symmetric stretching mode and that the NO2 group undergoes ultrafast structural deformation with a relaxation time of 195 fs. The frequency of the NO2 torsional mode in liquid NM（50.8±0.3 cm^-1） at room temperature is found. Our results prove the structural deformation of two groups in liquid NM molecule occur simultaneously in the intense laser field.

外加静电场对O_(2)分子高次谐波的调制机制(特邀)

采用了Lewenstein强场近似方法,计算了外加静电场对O_(2)分子在线偏振激光场中高次谐波产生的影响。结果表明:1)当静电场方向平行激光偏振方向时,谐波谱出现双平台结构,截止频率增大,偶次和奇次谐波幅度相当;2)当静电场方向垂直时,谐波谱呈现单平台结构,偶次谐波比奇次谐波的幅度小两个量级左右;3)外加静电场对双心干涉极小值的位置基本没有影响。利用Lewenstein理论,可以将分子谐波谱视为分子两端电离通道产生谐波的叠加,对外加静电场控制高次谐波提供了参考。

哈龙1301分子在外电场中的光谱特征和解离特性

哈龙1301(三氟溴甲烷)在太阳光辐射下解离生成破坏臭氧的溴自由基,严重破坏大气臭氧层,采用有效的措施对哈龙1301排放前进行降解很有必要。利用密度泛函理论(DFT)在B3LYP/6～311G++(d,p)水平上研究了外电场(0～0.03 a.u.)作用下哈龙1301分子的解离特性和光谱特征,包括总能量,键长,电偶极矩,LUMO-HOMO能隙,红外光谱以及解离势能面等。计算结果表明,在C——Br键连线Z方向上,外电场从0逐渐增加到0.03 a.u.时,分子体系能量逐渐减小,偶极矩在刚开始表现为减小然后单调增大,HOMO-LUMO能隙E_G呈现单调递减的趋势,C——Br键键长逐渐增大,C——F键键长逐渐减小。外电场对CF_3Br分子不同振动模式的红外光谱影响不同。在外电场作用逐渐增强下,解离特性表现为:CF_3Br分子的C——Br键方向扫描得到的势能曲线的束缚状态逐渐被消除,势垒逐渐变小最后消失。计算发现强度为0.03 a.u.的外电场足够使得CF_3Br分子发生C——Br键断裂而降解,该结果为保护环境而对哈龙进行电场降解提供重要参考依据。

典型龟裂碱土土壤光谱特征影响因素研究

为了提高基于土壤光谱特征预测土壤盐渍化程度的准确性,需要研究土壤光谱特征的因素影响。该文通过对野外、室内预处理、不同含水率、粒径和粗糙度条件下龟裂碱土表层土壤光谱的测定,系统研究了不同因素对龟裂碱土光谱特征的影响。结果表明：土壤碱化程度越强表层土壤光谱反射率越高,在450~925 nm范围内,碱土表层野外光谱反射率比重度、中度、轻度碱化土壤和非碱化土壤野外光谱反射率高7.36%、23.18%、32.10%和39.97%;765、945和974 nm附近是龟裂碱土盐渍化信息的敏感波段;相同土壤经过室内预处理后反射率明显低于野外土壤,且预处理后不同碱化程度土壤间光谱反射率差异也小于野外光谱。土壤含水率较低时,随着土壤含水率的增加土壤光谱反射率逐渐降低,但当含水率高于田间持水率时土壤反射率随土壤含水率的增加而增加,在整个研究波段含水率为26.45%时土壤反射率较含水率为22.33%和25.39%的反射率平均分别升高39.68%和19.79%。土壤粒径越小反射率越高,较大粒径土壤在760~768 nm形成独特的＂双峰＂现象。土壤粒径越大反射率受表面粗糙度的影响越小,且土壤表面越粗糙光谱吸收率越大。整体来讲,在450~1000 nm波段范围内,不同碱化程度的龟裂碱土野外表层土壤光谱特征差异显著;室内经过预处理后的龟裂碱土土壤光谱特征差异主要取决于土壤含水率,而碱化程度和土壤表面粗糙度的变化对其影响较小。该研究可以为龟裂碱土盐渍化信息的准确预测提供科学依据。

0.23T稳恒磁场对不同温度离体过氧化氢酶的磁效应研究

研究了 0 .2 3T稳恒磁场对不同温度下的离体牛肝过氧化氢酶 (CAT)构象及活力的影响 ,并从分子水平讨论了磁场对不同温度的过氧化氢酶产生不同生物学效应的可能机制。将不同温度的天然酶液置于磁感应强度为0 .2 3T的磁场中分别处理一定的时间 ,处理过程中保持环境温度与酶液温度一致 ,撤离磁场后立即在相同实验条件下对其进行光谱分析及量热分析 ,并用Beers&Sizers法 (改良型 )测定酶活力。结果表明 ,磁场使 2 5℃过氧化氢酶的构象发生明显变化 ,表现为荧光偏振度增加、出现明显的差示扫描量热曲线、产生λ2 10nm～ 310nm的紫外差光谱以及λ330nm荧光发射峰的荧光强度改变 (荧光发射峰的峰位未移动 ) ,构象变化的同时酶活力增加 ;15℃过氧化氢酶的构象及活力变化规律与 2 5℃过氧化氢酶类似 ,但强度均弱于 2 5℃酶 ;而 4℃过氧化氢酶的构象及活力没有发生变化 ,表现出未受磁场处理的影响。相同实验条件下 ,磁场对不同温度的酶分子影响不同 ,随温度的增加 ,影响效应趋于显著。由于不同温度的酶分子之间的差异在于构象状态的不同 ,这表明酶分子自身的构象状态对磁场处理效果有极其重要的影响。不同温度的过氧化氢酶磁效应差异显著可能是由磁致酶构象变化的特殊机制所引起。磁场对酶分子构象的影响可能是通?

基于实测波谱标识的Hyperion数据岩性识别方法

以中甸普朗典型斑岩铜矿区和松诺典型矿点的2种主要含矿岩性为实验研究对象,将特征岩性实测波谱数据转换为Hyperion影像像元数据,并利用MNF变换对高光谱数据进行降噪和降维,以第一个MNF变换主成分作为分析数据,以所构建像元的亮度值为参考分割点,通过密度分割,进行岩性识别,并通过与已有的地质资料的对比分析和野外调查,验证结果的精度。实验结果证明,在影像处理过程中有机地融入地面实测波谱,可较有效地识别中甸地区与矿相关的石英二长斑岩和石英闪长玢岩。

强稳恒磁场对离体牛肝过氧化氢酶构象及活力的影响

目的:研究了强稳恒磁场对离体牛肝过氧化氢酶（CAT）构象及活力的影响。材料与方法:将天然酶液置于不同磁感应强度的磁场中处理不同的时间脱离磁场后立即对其进行光谱分析,并用Beers＆Sizers法（改良型）测定酶活力。结果:磁场使过氧化氢酶的构象发生变化,表现为λ=210～310nm的紫外差光谱以及λ=330nm荧光发射峰的荧光强度改变;构象变化的同时酶活力增加。结论:磁场对酶分子的影响可能是导致机体宏观磁效应产生的重要原因。

翅碱蓬野外光谱对土壤化学性质的响应

翅碱蓬(Suaeda salsa)是土壤盐渍化较为严重的地区常见的植被类型,研究翅碱蓬群落特征可以间接反映下方土壤的化学性质。通过野外采集的17个翅碱蓬野外光谱数据和相应土壤样品的理化分析数据,探讨了土壤化学性质和翅碱蓬野外光谱之间的关系。结果表明,翅碱蓬二阶导数光谱1 121nm波段可用来反映土壤有机质和全氮的含量变化,二阶导数光谱1 208nm波段可以很好地反映土壤全磷的含量变化,一阶导数光谱353nm波段可以很好地反映土壤速效钾的含量变化最好,二阶导数光谱724nm波段可以很好地反映土壤pH值的变化,而反映土壤盐分含量变化最好的为一阶导数光谱950nm,这为翅碱蓬覆盖的区域利用遥感技术进行土壤化学性质监测奠定了基础。

鸟嘌呤红外光谱的密度泛函理论研究──标度量子力学(SQM)力场处理

用密度泛函理论 DFT( B3 LYP) /6-3 1 G* 方法对鸟嘌呤分子的酮 -胺式和醇 -胺式异构体的几何结构、振动谐性力场和红外光谱进行了研究 .理论力场由迁移自相关分子异胞嘧啶和咪唑的力常数标度因子进行标度 .算得振动频率与鸟嘌呤的实验基质隔离 IR光谱比较平均偏差对酮 -胺式和醇 -胺式分别为 6.6和 6.0cm- 1 .根据振动频率的势能分布和