首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 171 毫秒
1.
低能离子对氨基酸损伤的红外光谱研究   总被引:1,自引:0,他引:1  
分别轻注入机和气体常压孤光放电产生的你了子作用于固态和溶液中的氨基酸,研究了样品红外光谱的变化。结果表明,两种方式产生的离子对氨基酸有相同或相似的损伤作用,如分子重排、外来离子沉积等,而且低能离子作用于溶液样品表现出更显著、更丰富的损伤效果。  相似文献   

2.
低能氮离子对腺嘌呤水溶液损伤作用的光谱分析   总被引:1,自引:1,他引:0  
利用气体常压弧光放电产生低能N^ 离子,在阴极位降的加速下被注入到腺嘌呤(A)水溶液中,研究了低能N^ 离子作用后腺嘌呤水溶液的紫外,红外及核磁共振光谱的变化。结果表明,低能N^ 离子的注入对溶液样品造成了多种形式的损伤,其中不仅包括N^ 直接与水作用,还包括溶液中各种碎片之间重新化合,形成丰富多采的损伤产物。  相似文献   

3.
利用N2常压弧光放电产生低能N^ ,经电场加速后注入胞嘧啶(C)水溶液,研究了低能N^ 作用后胞嘧啶水溶液的紫外及红外吸收光谱的变化。结果表明,低能N^ 对溶液样品造成成了多种形式的损伤,形成丰富多彩的损伤产物,其中不仅包括水溶液中多种损伤碎片之间的重新化合,还包括N^ 与溶液中元素形成新的化学基团,继而与其他碎片结合形成产物,使外来的N^ “沉积”在溶液样品中。  相似文献   

4.
间接驱动惯性约束聚变真空或者近真空黑腔实验中,纳秒激光烧蚀产生的腔壁等离子体可以在靶丸烧蚀等离子体(或低密度填充气体)中驱动无碰撞静电冲击波,冲击波电场会以二倍冲击波速度反射离子。为了测量纳秒激光驱动非相对论无碰撞静电冲击波产生的10 keV量级的反射离子能谱,设计了低能汤姆逊离子谱仪。利用Geant4建模,对离子测量过程进行了全过程蒙特卡罗模拟,用以评估靶室残余气体和喷气气体对低能离子测量的影响。模拟结果显示,靶室残余气体会造成10 keV量级D离子信号在谱仪电场和磁场方向展宽。电场方向的展宽会增加不同荷质比离子谱线发生交叠的风险,而磁场方向的展宽会导致离子能谱展宽。喷气气体会造成离子信号向低能区移动并拖尾,导致测量的离子谱偏离真实的反射离子能谱。  相似文献   

5.
利用垂直交叉的激光束在Paul阱中溅射固体铸铁(FeC)靶,产生了低能多电荷铁离子 Fen+(n=1—3), 得到了Fe3+离子在本底气压为3.0×10-7 Pa下的衰减速率(0.96 s-1)以及在1.3×10-5 Pa下和中性气体分子N2的反应产物. 关键词: Paul阱 低能多离化离子 反应特性  相似文献   

6.
利用垂直交叉的激光束在Paul阱中溅射固体铸铁(FeC)靶,产生了低能多电荷铁离子Fen+(n=1-3),得到了Fe3+离子在本底气压为3.0×10-7Pa下的衰减速率(0.96s-1)以及在1.3×10-5Pa下和中性气体分子N2的反应产物.  相似文献   

7.
采用蒙特卡罗模型对氮空心阴极放电等离子体鞘层离子(N2 、N )的输运过程进行了模拟研究,计算了阴极鞘层中氮离子(N2 、N )的能量及角分布的空间变化和粒子密度及平均能量随放电参数的变化规律。研究结果表明:空心阴极放电产生的氮离子,在鞘层输运过程中,N2 是密度几乎不变的低能粒子;N 是密度逐渐减少的高能粒子。随着电压增加,N 密度减小,平均能量增加;N2 密度和平均能量变化不明显。能量及入射角的相对分布规律与平板电极氮直流辉光放电基本类似,但圆筒空心阴极放电更有利于氮离子的产生。  相似文献   

8.
高克林  朱熙文 《物理》1992,21(5):311-313
近年来,各种形式的离子阱作为“清洁”的离子存储器被应用于低能高电离态离子的碰撞和光谱学的研究.同步辐射作为一种新型光源,其能量范围宽,产生的光子能量高,是高电离态产生、电离和激发的有力手段.把二者的优点结合起来,可开辟新的科学生长点.[1] 研究低能高电离态离子,对于实验室等离子体和天体等离子体中的光电离和碰撞过程;对于量子电动力学的精密检验; 对于研究高电离态离子的能极结构和谱线;对于检验和发展光电离以及其他光与离子相互作用理论,都具有非常重要的意义,是当前原子、分子物理学的重要研究前沿. 利用同步辐射光产生离子…  相似文献   

9.
结合脉冲放电气体束和激光溅射技术,开发了一套产生气相金属化合物分子和离子的装置。利用飞行时间质谱测试了金属铜靶与不同气体反应的离子产物和效率,并利用激光诱导荧光光谱方法测量了自由基分子产物的状态。测试结果表明,该装置可有效产生气相金属化合物自由基分子和离子,而且产物转动温度低,为下一步开展高精度金属化合物分子自由基电子态激光光谱研究打下了基础。  相似文献   

10.
邱华檀  王友年  马腾才 《物理学报》2002,51(6):1332-1337
考虑了离子与中性粒子的弹性碰撞和电荷交换碰撞效应,建立了一套描述射频等离子体鞘层动力学特性的自洽模型,并利用MonteCarlo模拟方法研究了入射到电极上的离子的能量分布和角度分布.数值结果表明:随着放电气压增加,入射到电极上离子的能量分布逐渐地由双峰分布变成单峰分布,而且低能离子的数目也逐渐地增加.入射到电极上的离子呈小角分布,而且放电气压等参数对角度分布的影响不是太明显. 关键词: 射频放电 等离子体 离子 鞘层  相似文献   

11.
高气压非平衡等离子体化学及应用基础研究   总被引:7,自引:0,他引:7  
白希尧 《物理》2000,29(7):406-410,435
文章概述了气体放电、非平衡等离子体化学研究现状与发展趋势,提出了高气压非平衡等离子体新概念,应用特种新工艺实施高气压强电场(〉400Td)放电获得高能(〉10eV)电子的方法,激励气体分子分解、电离成离子、原子、激发态原子(及分子)和自由基等,按预定模型合成新物质、新分子,使常规难以进行的化学反应得以进行或加速进行,高气压非平衡等离子体化学具有极其广阔的应用前景。  相似文献   

12.
ABSTRACT

The dielectric thermal and non-thermal properties of sodium chloride aqueous solution under the microwave region have been estimated. The dielectric properties, hydrogen bonding, transport properties, energy distribution and local structure have been evaluated by classical molecular dynamics method. In the process of microwave energy distribution, the direct coupling of rotational motion, vibration and redirection is revealed. Microwave energy is converted into kinetic energy and interaction energy between two molecules. A mechanism for exploring the effects of microwaves on the non-thermal effects of brine systems over a longer simulation time and a wider microwave range is proposed. The increase in field intensity is usually accompanied by local damage to the water structure near the hydrated ions. More specifically, above the field threshold, the residence time of water molecules near the ions significantly decreases.

Highlights
  1. Microwave energy is transferred to the kinetic energy and the energy between the molecules.

  2. The increase in field intensity is usually accompanied by local damage to the water structure near the hydrated ions.

  3. The larger electric field strength amplifies the effect of frequency.

  4. The residence time of water molecules near the ions significantly decreases.

  相似文献   

13.
对胶原分子聚集行为的研究,不仅能改善其理化特性,同时也为其在食品、组织工程和生物医药等领域的应用提供理论指导。基于胶原分子中苯丙氨酸(Phe)和酪氨酸(Tyr)的内源荧光特性,采用常规波长、同步荧光和二维(2D)荧光光谱技术研究了不同浓度和温度下胶原分子的聚集行为。研究结果表明:(1)在激发波长275 nm条件下,胶原分子仅在发射波长303 nm处出现了归属于Tyr的特征峰;选取波长差(Δλ)为15 nm的同步荧光扫描胶原分子,发现其在261和282 nm处出现了分别归属于Phe和Tyr的特征峰。(2)特征峰的荧光强度与胶原浓度呈现良好的线性关系,表明了基于常规波长和同步荧光光谱技术对胶原定量分析的可行性。(3)随着胶原浓度的增加,Tyr和Phe的含量逐渐增大,且胶原分子间距逐渐降低并聚集成纤维束,使得Tyr和Phe相互靠近并参与形成大量的氢键,从而导致荧光强度不断增大。然而随着温度的升高,荧光基团与溶剂碰撞的猝灭机会增大,且胶原分子中Tyr和Phe的荧光量子产率逐渐降低,同时胶原分子动能增大,其聚集体逐渐松散,其三股螺旋结构逐渐坍塌,Tyr和Phe参与形成的氢键被破坏,从而导致荧光强度随温度的升高不断降低。(4)275 nm常规波长的2D荧光光谱分析表明,胶原分子在297,303和310 nm处出现了相关峰,其中303 nm归属于Tyr,297 nm归属于胶原分子聚集过程中参与氢键形成的Tyr;310 nm可能归属于Tyr的激发态,其不断的蓝移形成稳定的基团,以便参与氢键的形成,从而促进了胶原分子的聚集。以浓度为外扰的基团响应顺序为303 nm>297 nm>310 nm;以温度为外扰的基团响应顺序为297 nm>310 nm>303 nm。(5)2D同步荧光光谱分析表明,随着胶原浓度和温度的升高,Phe均比Tyr优先响应。综上,采用常规波长、同步荧光光谱技术均能较好的研究胶原分子在不同浓度和温度下的聚集行为,且为胶原的定量分析提供了一种新的方法,但同步荧光光谱技术可将量子产率较低的Phe显现出来,体现了其具有窄化谱带和提升分辨率的优点。此外,结合2D荧光分析技术,可进一步研究胶原分子基团的响应顺序。  相似文献   

14.
These studies are focused on understanding the role played by a solvent in chemical and electronic processes occurred in the course of semiconductor surface passivation at semiconductor/electrolyte interface. It is shown that the chemical reactivity of the ionic adsorbate at a semiconductor/electrolyte interface can be changed considerably through interaction with solvent molecules. The reactivity of anions depends essentially on the solvating solvent: hydrated ions could be either slightly electrophilic or slightly nucleophilic, whereas the ions solvated by alcohol molecules are always strongly nucleophilic. Mechanism of interaction of such solvated ions with the semiconductor surface atoms depends on the solvent, as is demonstrated by the example of processes occurred at GaAs(1 0 0)/sulfide solution interfaces. It is found that on adsorption of HS ions from different solvents the AsS bonds with solvent-dependent ionic character are formed on a GaAs(1 0 0) surface. The surface obtained in such a way possesses different ionization energy and exhibit different electronic properties dependent on the solvent.  相似文献   

15.
The energy transfer between different pairs of lanthanide ions bonded by fluoride bridges into labile binuclear complexes is studied in aqueous solution at different ratios between the concentrations of lanthanide ions and fluoride anions ([Ln]: [F]). It is shown that, if the concentrations [Ln] and [F] are of the same order of magnitude, the energy transfer rate constant k t does not depend on the choice of the pairs of interacting ions and is determined by the association rate constant of Ln(III) ions into binuclear complexes. If the concentration of the lanthanide ions is much greater than that of the fluoride ions, k t varies proportionally to the monomolecular energy transfer rate constants in the binuclear complexes. It is assumed that, in the first case, Ln(III) ions are bonded through two fluoride anions, whereas, in the second case, they are bonded through one anion. The analysis of the variations in k t in the latter systems shows that the exchange-resonance mechanism should be taken into account for the explanation of the experimental data. The effects that the introduction into the solution of different contents of salts of strong acids—AlCl3, MgCl2, Ca(NO3)2, CsCl, RbBr, and NaCl—have on k t and on the regularities of the energy transfer between Ln(III) ions bonded into binuclear fluoride complexes are studied. The effects of these electrolytes on the luminescence intensity and spectrum of Eu(III) ions and on the values of k t for the energy transfer between Ln(III) ions bonded into binuclear complexes are analyzed. It is shown that, at some concentration ratio [Ln]: [F], for all electrolytes studied except AlCl3, the value of k t increases despite the fact that the concentration of mononuclear complexes of Ln(III) ions with fluorine decreases in the presence of these electrolytes. It is ascertained that the anions of strong acids in the outer sphere of lanthanide ions increase the association constant of Ln(III) ions in binuclear fluoride complexes.  相似文献   

16.
In this paper, the toluidine blue (TB) with tricyclic quinone imide plane structure is used as sonosensitizer to study the interaction and sonodynamic damage to bovine serum albumin (BSA) by UV-vis and fluorescence spectroscopy. The results show that the TB can bind to BSA molecules, obviously, and the synergetic effects of TB and ultrasonic irradiation can efficiently damage the BSA molecules. Otherwise, some influencing factors such as ultrasonic irradiation time, TB concentration, pH value and ionic strength on the damage of BSA molecules were also considered by the numbers. Synchronous fluorescence spectroscopy indicates that the tyrosine (Tyr) residues of BSA molecules are damaged more seriously than the tryptophan (Trp) residues under ultrasonic irradiation.  相似文献   

17.
We present the results of quantumchemical investigation of energy transfer in organic molecules and systems and the inferences drawn. The Förster theory has been subjected to a critical analysis in order that the energy transfer could be described in the context of the current theory of nonradiative transitions and the incorrectness of the basic premises of the Förster theory has been demonstrated. A new variant of the mechanism of electronic energy transfer on the basis of the theory of electron transitions and of the quantum mechanics of molecules has been suggested. It is shown that the interaction of the molecules of the donor and acceptor perturbs the electronic states of isolated molecules even before the excitation of the donor molecule. A characteristic feature of the manifestation of intermolecular interaction is the spatial delocalization of the wave functions of the electronic states of interacting molecules, leading to the possibility of occurrence of conventional photophysical processes with participation of the electronic states of various molecules of the bimolecular system. In experimental investigations, the result of the intermolecular nonradiative transition is recorded as evidence of the spatial transfer of the energy of electronic excitation from the donor molecule to the acceptor molecule.  相似文献   

18.
Here we report the first mass spectrometric study of negative ions formed via free electron attachment (EA) to nucleobases (NBs) embedded in helium clusters. Pure and mixed clusters of adenine and thymine have been formed by pickup of isolated NB molecules by cold helium droplets. In contrast to EA of isolated molecules in the gas phase we observe a long-lived parent anion NB- and, in addition, parent cluster ions NB-n up to size n=6. Moreover, we show that a low energy electron penetrating into a doped helium droplet causes efficient damage of the embedded nucleobases via resonant, site selective, dissociative electron attachment.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号