化学系专业外语课件7.Ultraviolet Spectroscopy
应用化学专业英语第二版万有志主编版课后答案和课文翻译
应⽤化学专业英语第⼆版万有志主编版课后答案和课⽂翻译Unit 1 The Roots of ChemistryI. Comprehension.1.C2. B3. D4. C5. BII. Make a sentence out of each item by rearranging the words in brackets.1.The purification of an organic compound is usually a matter of considerable difficulty,and it is necessary to employ various methods for this purpose.2.Science is an ever-increasing body of accumulated and systematized knowledge and isalso an activity by which knowledge is generated.3.Life, after all, is only chemistry, in fact, a small example of chemistry observed on asingle mundane planet.4.People are made of molecules; some of the molecules in people are rather simplewhereas others are highly complex.5.Chemistry is ever present in our lives from birth to death because without chemistrythere is neither life nor death.6.Mathematics appears to be almost as humankind and also permeates all aspects ofhuman life, although many of us are not fully aware of this.III. Translation.1.(a) chemical process (b) natural science (c) the technique of distillation2.It is the atoms that make up iron, water, oxygen and the like/and so on/and soforth/and otherwise.3.Chemistry has a very long history, in fact, human activity in chemistry goes back toprerecorded times/predating recorded times.4.According to/From the evaporation of water, people know/realized that liquids canturn/be/change into gases under certain conditions/circumstance/environment.5.You must know the properties of the material before you use it.IV. Translation化学是三种基础⾃然科学之⼀,另外两种是物理和⽣物。
Ultraviolet photoemission spectroscopy
Instrumentation
UV source
In UPS, a He discharge lamp is usually used to generate He I (21.2 eV) and He II (40.8 eV) emissions.
Discharge chamber High tension
UV source Synchrotron radiation
Principles UV Photoemission analysis
Angle-integrated UPS Angle-resolved UPS
Nomenclature
Nomenclature
• X-ray photoelectron spectroscopy, XPS is also known as “Electron Spectroscopy for Chemical Analysis (ESCA) 化学分析用电子能谱”. • Actually, it belongs to a family of Photoemission Spectroscopy (PES) 电子 能谱, in which a photon source is used to excite a sample surface, the energy of those electrons ejected after the photoemission process (photoelectrons) are detected and analyzed. Specifically, if x-ray is used as the photon source, the technique is named as “X-ray Photoelectron Spectroscopy (XPS)”. • If UV source is used instead, the technique is called the “Ultraviolet Photoemission Spectroscopy (UPS) 紫外光电子能谱” • With the emergence of Synchrotron Radiation同步辐射, tunable photon source can be generated.
分析化学英文课件10分光光度法 Spectrophotometry
2.Molar absorptivityε
(1) Characteristic constant under certain condition for a
certain substance.
(2) Not change with c and wave path b. Under certain
temperature and wave length,εis only decided by the
c: concentration, g·L-1
a: absorptivity, L·g-1·cm-1
a andε: a =ε/ M (M : molar mass)
Transmittance: T
T : ratio of the radiant power transmitted to the incident radiant power :
ε = (6~10)× 104 : high sensitive;
ε = (2~6)× 104 : medium sensitive
ε < 2 × 104
: not sensitive。
Discrepancy of Lambert-beer’s law
The relationship between the absorbance and concentration may be nonlinear, which is the discrepancy of Lambert-Beer’s Law. The discrepancy may be caused by:
The selective absorbance and absorbance
curve
M + h → M*
Chemistry English-070305
二、科技英语的主要特点
1. 语法特点 主要表现在四多, 主要表现在四多,即: (1)词类转换多 ) e.g. The operation of a machine needs some knowledge of its performance. (2)被动语态多 ) e.g. Mathematics is used in many different fields. People use mathematics in many different fields. (3)后置定语多 ) e.g. In addition to aliphatic compounds, there are a number of hydrocarbons derived from benzene and seemed to have distinctively different chemical properties. Besides, isomerization processes may also take place which in turn leads to other fairly complicated reactions. (4)复杂长句多 )
绿色化学( )(2学时 第七部分 绿色化学(Green Chemistry)( 学时) )( 学时) 1. 绿色催化 Green Catalysis 2. 绿色化工工艺 Green Chemical Technics 化工基础( )(2学时 第八部分 化工基础(Chemical Engineering)( 学时) )( 学时) 1. 物料衡算 Material Accounting 2. 蒸馏 蒸馏Distillation 第九部分 生命化学(Life chemistry)( 学时) 生命化学( )(2学时 )( 学时) 1. 生物化学 生物化学Biochemistry 2. 生物医学工程 生物医学工程Biomedical Engineering 第十部分 本届诺贝尔化学奖介绍 The Current Nobel Prize in Chemistry(2学时) 学时) ( 学时 英语科技论文写作( 第十一部分 英语科技论文写作(Scientific Papers Writing) ) 学时) (2学时) 学时
有机化学第七章光谱
一些常见化学键的力常数如下表所示:
键型 O H N H
-1
C H C O C C C O C C 4.8 17.7 15.6 12.1 9.6 5.4 4.5
k /N.cm
7.7 6.4
折合质量μ :两振动原子只要有一个的质量↓, μ ↓,(v)↑
C H 2800-3000cm
3.其他:
N-H弯曲振动在1600-1650cm-1 四个或四个以上CH2 相连,其CH2 的面内摇摆 振动在 720cm-1
7.1.4 红外谱图解析
红外谱图解析的基本步骤是:
1.观察特征频率区:判断官能团,以确定所属化 合物的类型。
2.观察指纹区:进一步确定基团的结合方式。 3.对照标准谱图验证。
E:光量子能量,J h: Planck常数, 6.626×10-34 J.S
分子吸收光谱 分子吸收电磁幅射,就获得能量,从而引起分子 某些能级的变化,如增加原子间键的振动,或激发 电子到较高的能级,或引起原子核的自旋跃迁等。 但它们是量子化的,因此只有光子的能量恰等于两 个能级之间的能量差时(即ΔE)才能被吸收。所以 对于某一分子来说,只能吸收某一特定频率的辐射, 从而引起分子转动或振动能级的变化,或使电子激 发到较高的能级。光谱便是记录分子对不同波长 (频率)的电磁波吸收或透过情况的图谱。
叔醇:1150~1120cm-1
4. 醛与酮
二者的异同点:
1. 在1700cm-1处均有一个强而尖的吸收峰,为 C= O(羰基)的特征吸收峰。 C=O(羰基)吸收峰的位置与其邻近基团有关, 若羰基与双键共轭,吸收峰将向低波数区位移。
2.醛基在2715cm-1处有一个强度中等的尖峰,这是 鉴别分子中是否存在— CHO的特征基团。
XPS 课件
纳米材料的现代表征技术-课件电子能谱石建英中山大学化学与化学工程学院电子能谱分类X射线光电子能谱(简称XPS)(X-Ray Photoelectron Spectrometer)紫外光电子能谱(简称UPS) (Ultraviolet Photoelectron Spectrometer)俄歇电子能谱(简称AES)(Auger Electron Spectrometer)对固体样品,必须考虑晶体势场和表面势场对光电子的束缚作用,通常选取费米(Fermi)能级为的参考点。
b E 0k时固体能带中充满电子的最高能级对孤立原子或分子,就是把电子从所在轨道移到真空需的能量,是以真空能级为能量零点的。
b E φ++=b k E E hv 功函数φ++=b k E E hv 功函数为防止样品上正电荷积累,固体样品必须保持和谱仪的良好电接触,两者费米能级一致。
实际测到的电子动能为:spb s sp k k E hv E E φφφ−−=−−=)('spkb E hv E φ−−='仪器功函数特征:XPS采用能量为的射线源,能激发内层电子。
各种元素内层电子的结合能是有特征性的,因此可以用来鉴别化学元素。
eV 1500~1000UPS采用或作激发源。
与X 射线相比能量较低,只能使原子的价电子电离,用于研究价电子和能带结构的特征。
I(21.2eV) He II(40.8eV) He AES大都用电子作激发源,因为电子激发得到的俄歇电子谱强度较大。
光电子或俄歇电子,在逸出的路径上自由程很短,实际能探测的信息深度只有表面几个至十几个原子层,光电子能谱通常用来作为表面分析的方法。
X-ray Photoelectron Spectroscopy (XPS)XPS BackgroundXPS technique is based on Einstein’s idea about the photoelectric effect, developed around 1905\The concept of photons was used to describe the ejection of electrons from a surface when photons were impinged upon itDuring the mid 1960’s Dr. Siegbahn and his research group developed the XPS technique.\In 1981, Dr. Siegbahn was awarded the Nobel Prize in Physics for the development of the XPS techniqueIntroduction•X-ray photoelectron spectroscopy works by irradiating a sample material with monoenergetic soft x-rays causing electrons to be ejected.•Identification of the elements in the sample can be made directly from the kinetic energies of these ejected photoelectrons.•The relative concentrations of elements can be determined from the photoelectron intensities.Introduction (XPS)---Analysis capabilities•Elements detected from Li to U.•None destructive (some damage to x-ray beam sensitive materials)•Quantitative.•Chemical state analysis (some exceptions)•Surface sensitivity from 5 to 75 angstroms.•Conducting and insulating materials.•Detection limits that range form 0.01 to 0.5 atom percent.•Spatial resolution for surface mapping from >10 mm •Depth profiling capabilities.Photoemission of ElectronsConduction BandValence BandL2,L3L1K Fermi LevelFree Electron Level (vacuum)Incident X -ray Ejected Photoelectron1s 2s2p¾XPS spectral lines are identified by the shell from which the electron was ejected (1s, 2s, 2p, etc.).¾The ejected photoelectron has kinetic energy:¾KE= hv –BE -φ¾Following this process, the atom willrelease energy by the emission of aphoton or Auger Electron.XPS Energy Scale -Binding energyBE = hv-KE -ΦspecWhere: BE= Electron Binding EnergyKE= Electron Kinetic EnergyΦ= Spectrometer Work FunctionspecPhotoelectron line energies: Not Dependent on photon energy.X-RaysIrradiate the sample surface, hitting the core electrons (e-) of the atoms.The X-Rays penetrate the sample to a depth on the order of a micrometer.Useful e-signal is obtained only from a depth of around 10 to 100 Åon the surface.The X-Ray source produces photons with certain energies: \MgKαphoton with an energy of 1253.6 eV\AlKαphoton with an energy of 1486.6 eVNormally, the sample will be radiated with photons of a single energy (MgKαor AlKα). This is known as a monoenergetic X-Ray beam.Why the Core Electrons?An electron near the Fermi level is far from the nucleus, moving in different directions all over the place, and will not carry information about any single atom.\Fermi level is the highest energy level occupied by an electron in a neutral solid at absolute 0 temperature.\Electron binding energy (BE) is calculated with respect to the Fermi level. The core e -s are local close to the nucleus and have binding energies characteristic of their particular element.The core e -s have a higher probability of matching the energies of AlK αand MgK α.Core e -Valence e -Atom电离截面σ: 光电离过程发生的几率•由于光电子发射必须由原子的反冲来支持,所以同一原子中轨道半径愈小的壳层σ愈大。
波谱分析绪论最新PPT课件[文字可编辑]
分子转动光谱:引起分子同一电子能级同一振动能级内转动 能级跃迁的光谱。远红外和微波区(25500μm)线光谱。
4.“四谱”的产生
带电物质粒子的质量谱( MS) ↑ ↗核外层电子能级跃迁 (UV) 分子 → 原子 ↓ ↘核自旋能级的跃迁( NMR)
振(转)动能级跃迁( IR)
4.不饱和度(unsaturated number )
(index of hydrogen deficiency ) 根据分子式计算不饱和度,其经验公式为:
式中:Ω—代表不饱和度;n 、n 、n 分别代表分
1
3
4
子中一价、三价和四价原子的数目。
双键及饱和环状结构的 Ω为1、三键为2、苯环为4。
OH O HO
NCH3 吗啡碱
1803年从鸦片中离析得到纯品; 1881年从吗啡的锌粉蒸馏得到菲; 1925 年 Gulland 和 Robinson 提 出
吗啡 分子的结构式; 1952~1956年完成吗啡的全合成。
历 时 149
二、波谱分析
20世纪中期以后 ,采用现代仪器分析法,其 特点是:
? 样品用量少,仅需毫克级甚至微克级纯样; ? 分析方法多为非破坏性过程(质谱除外); ? 分析速度快。
“四谱”的产生?
苯丙烯酸的低分辨质谱、红外、 60MHz核磁、紫外光
三.电磁辐射与谱学基础
1.电磁辐射基础
电磁辐射是高速通过空间传播的光子流,具有 波动性和微粒 性。辐射能的发射和吸收是量子化的,其能量的最小单位为
“光子”。每个E光子=所h具v有=的能h(量c/(?E)L)=为:hc L
化学相关专业英语(课堂PPT)
❖ Scientific disciplines represent abstract bodies of knowledge(科 学学科代表知识体)
❖ Technology is the physical application of scientific knowledge to
the production of new products to improve human survival, comfort(n. 安慰;舒适;使人舒服的事ቤተ መጻሕፍቲ ባይዱ;给予援助或安慰的人或事
English Curse of Chemistry
Huiming L1in
教材:
1、《化学专业英语》
(周光明,西南师范大学出版社)
2、《化学专业基础英语》
(魏高原,北京大学出版社)
3、《化学与化工英语》
(张荣,华中科技大学出版社)
4、《化学与应用化学专业英语》 (王辛宜,华东理工大学出版社)
2
Why must we study the course? The content of the course
❖ ) pace(n. 一步;长度单位;步幅,步调;快步
vt. 踱步,走来走去;步测;调整步调;训练马溜蹄 vi. 踱;溜蹄 prep.
蒙…恩准,怀着对…的敬意), to have a major impact on human
society)技术是科学知识来生产新的产品来改善人类的生存,舒适的物
理应用,和生活质量(技术进步开始影响我国社会约200年,和新的进
6
what is chemistry and why is it important
➢ Why is it important chemistry plays a pivotal role in the natural sciences. It provides the essential basic knowledge for applied sciences, such as astronomy, materials sciences, chemical engineering, agriculture, medical sciences and pharmacology.
第一章 紫外光谱
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18Eσ* Nhomakorabeaπ*
π
* 4
π
* 3
n
π
π2
π1
σ
C-C C=C C=O
C=C-C=C
能级跃迁图
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三、 分子吸收光谱的表达(紫外光谱图)
UV:A~λ;IR:T~ v 有时仅记录吸收峰的相关参数:λmax和εmax
Ultraviolet Absorption Spectrometry
3. B吸收带(Benzenoid):苯环π→π*跃迁产生,
230-270nm , 中 心 在 256nm 处 , 宽 而 弱 , 有 精 细 结
构,是苯环的特征吸收ε约220
4. E吸收带(Ethylenic):芳环中碳碳双键π→π* 跃迁产生,在184(E1)( ε约60000)和204(E2)nm 处( ε约7900)。
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二、分子能级图
1. 分子能级
分子的总能量:
E = Et + Ee + Ev + Er 其中:Et(平动动能)是连续的,分子光谱 主要取决于Ee(电子能量)、Ev(振动能量) 和Er(转动能量) 的变化,即:
E = Ee + Ev + Er 这些能量都是不连续的、量子化的
分子能级图:
吸收带: K带; R带 含硫化合物:类似于醇、醚和羰基化合物,
吸收带λmax较大。
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二、共轭双键化合物
跃迁类型: σ→σ*;π→π*; (n →π*)
吸收谱带: K(、R)吸收带
Woodward等人提出了一套计算此类化 合物π→π*跃迁的λmax的方法,可用于确定 此类化合物的可能结构。
化学专业英语
(1)词根
carbo-
carbon
碳 sulf- sulfur
硫
hydro- hydrogen 氢 chloro- chlorine
氯
oxy-
oxygen
氧 fluoro- fluorine
氟
nitro-
nitrogen 硝基 bromo- bromine
溴
phospho- phosphorus 磷 iodo- iodine
Terms Used in Chemistry
Precipitate (沉淀物). A precipitate is a solid separated from a solution.
• Radical (根,基,原子团). A radical is an atom or a group of atoms reacting as a unit.
pyroarsenic acid H4As2O7 焦砷酸 pyroarsenate M4As2O7 焦砷酸盐
pyroarsenous acid H4As2O5 焦亚砷酸 pyroarsenite M2As2O5 焦亚砷酸盐
hypophosphorous acid H3PO2 次磷酸 hypophosphite M3PO2 次磷酸盐
hypoiodous acid HIO 次碘酸 hypoiodite MIO 次碘酸盐
hypochlorous acid HClO 次氯酸 hypochlorite MClO 次氯酸钠
(C): pyro- 焦
0.5 M (0.5 mol/Liter)
• Equation ( 方 程 式 , 反 应 式 ) . An equation is a
shorthand (速记) statement of the materials entering into a reaction, the products formed and the ratio in which combination takes place.
应用化学专业外语词汇
Aabscissa[æbˈsɪsə] n. 横座标 abundance n. 丰富, 充裕acceptor n. 接受体accumulator n. 储料器 acetic acid n. 醋酸, 乙酸 acknowledge v. &n. 致谢activation n. 活化acylation ['æsil] n. 酰化addition [əˈdiʃən] n. 加成反应adhesive [ædˈhisɪv, -zɪv] n. 粘合剂advancement n. 进展,增长advantageous adj. 有利的aerosol[ˈeərəˌsɔ:l, -ˌsɔl] n. 烟雾affinity [əˈfɪnɪti:] n. 亲合力agent [ˈeidʒənt] n. 试剂aldehyde [ˈældəˌhaɪd]n. 醛aldol[ˈældəul]n. 醛醇aliphatic acid [ˌæliˈfætik]n. 脂肪酸alkaline[ˈælkəlɪn, -ˌlaɪn] adj. 碱的alkaloid[ˈæl kəlɔid] n. 生物碱alkane[ˈælˌken]n. 烷烃alkene[ˈælki:n]n. 烯烃alkylation [ˌælkiˈleiʃ(ə)n]n. 烃化, 烷基化alkyl halide[ˈælkil][ˈhælaid]n. 烷基卤, 卤烷alkyne n. 炔alphabetic adj. 依字母顺序ambiguity n. 模糊, 意义不明确amide n. 酰胺amine n. 胺amino acid n. 氨基酸amorphous adj. 无定形analogue n. 类似物anhydride n. 酸酐aniline n. 苯胺anion n. 阴离子anomaly n. 异常,反常antibiotics n. 抗菌素antifreezing agent n. 抗冻剂antioxidant n. 抗氧剂appreciable adj. 可估计的architect n. 建筑师, 设计师arene n. 芳烃aromatic adj. 芳香的aromatization n. 芳构化asymmetric adj. 不对称的autooxidation n. 自氧化awarenness n, 意识azeotrope n.共沸混合物azo dye n. 偶氮染料Bbackup n. /adj 备用设备base n. 碱, 基, 底beaker n. 烧杯benzene n. 苯biological degradation n. 生物降解biosynthesis vt. 生物合成bleach vt. 漂白bond n. 键branched chain n. 支链budget n. & v. 预算bubble-cap tower n. 泡罩塔buffer n. 缓冲,缓冲剂Ccarbanion n. 负碳离子, 阴碳离子carbene n. 碳烯, 卡宾carbide n. 碳化物, 碳化钙carbocation n. 正碳离子, 阳碳离子carbonyl group n. 羰基carboxy group n. 羧基carboxylic acid n. 羧酸carcinogenic adj. 致癌的β-carotene n. β胡萝卜素carrier n. 载体cartridge n. 软片暗盒catalysis n. 催化(作用) cation n. 阳离子cellulose n. 纤维素ceramic adj/n. 陶瓷(的) chemical shift n. 化学位移chirality n. 手性chlorination n. 氯化作用chlorohydrocarbon n. 氯代烃chromophore n. 发色团cis-trans isomer n. 顺反异构体classic adj. 经典的, 传统的cluster n. 蔟,一串,一束coherent adj. 黏附的,相干的(光学) coil n. 蛇管colorant n. 颜料,着色剂commodity n. 用品compensation n. 补偿competitive n. 竞争的complementary n. 补充的complex n. 络合物complication n. 复杂concerted reaction n. 协同反应condensation n. 缩合反应condiment n. 调味品conformation n. 构象conjugation n. 共轭construction n. 建设, 建筑consultant n. 顾问consumer n. 消耗container n. 容器containment n. 抑制cooler n. 冷却器corporate adj. 共同的correlate n. 相关的事物cosmetic n. 化妆品counteract vt. 抵消,抵抗coupling reaction n. 偶合反应covalent bond n. 共价键critical adj. 临界的cumulative adj. 累积的,累加的customary adj. 通常的, 常例的cycloparaffin n. 环烷烃Ddecolorant n. 脱色剂decolorize v. 脱色degradation n.降解dehydration n. 脱水作用dehydrogenation n. 脱氢作用delocalization n. 离域作用denatured alcohol n. 变性酒精denominator n. 分母derivation n. 衍生,由来derivative n. 衍生物desorption n. 解吸作用destructive distillation 分解蒸馏detergent n. 洗涤剂developer n. 显影剂dextrorotary adj. 右旋的diazonium salt n. 重氮盐diazotization n. 重氮化作用dielectric adj.不导电的,n.电介质dipole n. 偶极directory n. 地址录disclose vt. 揭露, 揭发discrete adj. 离散的,不连续的disposal vt. 排出, 处理director n. 定位基dissolve v.溶解distillation n. 蒸馏dominant adj. 支配的,统治的donor n. 给体drastic n. 激烈的, 猛烈的droplet n. 液滴dyestuff n. 染料Eelectrophilic reagent n. 亲电试剂electrophobic adj 疏电子的electronegative adj 电负性的electron withdrawing group n. 吸电子基electrostatic adj. 静电的elimination n. 消除反应emulsion n. 乳剂endothermic adj. 吸热的enantiomer n. 对映体enzyme n. 酶epoxy adj. 环氧化的essential oil n. (香)精油ester n. 酯esterification n. 酯化作用ethanol n. 乙醇ether n. 醚, 乙醚ethyl n. 乙基ethylene n. 乙烯ethynyl n. 乙炔基evaluation n. 评价,估价evaporation n. 蒸发excitation n. 激发态exothermic adj. 放热的extract vt. 萃取extrapolation n. 推断Ffermentation n. 发酵fiber n. 纤维filament n. 细丝,丝状体filter n.过滤器,滤色片flare v. & n. 闪耀, 闪烁flavoring n. 香剂, 调味剂fluorescent n. 荧光fore adj. 先时的, 前部的formaldehyde n. 甲醛fossil n. 化石fractional distillation n. 分馏free radical n. 自由基fumigant n. 熏蒸(消毒)剂functional group n. 官能团furan n. 呋喃Ggeneralization n. 一般(性), 普遍(性) genetic code n. 遗传密码geological adj. 地质(学)的geomatrical adj. 几何学的glacial acetic acid n. 冰醋酸glucose n. 葡萄糖glycerol n. 甘油, 丙三醇graphics n. 图,制图法Hhabituation n. 习惯作用, 毒瘾halogenation n. 卤化hazardous adj. 危险的, 有危害的herbicide n.除草剂heterocyclic compound n.杂环化合物heterogeneous adj. 非均相的, 多相的hexagon n. 六边形highlight n. 光线明亮处hold-up n. 塔储量, 容纳量homologous series n. 同系列hormone n. 激素humectant n. 润湿剂hybrid n. 杂化hydration n. 水合作用hydrogenation n. 氢化作用hydrolysis n. 水解hydrophobic adj. 疏水的hydroxyl group n. 羟基Iidealize vt. 理想化inasmuch as adv. 因为, 由于indicator n. 指示剂indiscriminate adj. 不加选择的indol n. 吲哚inductive effect n. 诱导效应ineffective adj. 无效的, 低效率的infrared spectroscopy n. 红外光谱ingenious adj. 坦率的, 天真的ingestion n. 吸收, 吸入inlet n. 进口, 入口insecticide n. 杀虫剂insulin n. 胰岛素integrate vt. 积分,使...一体化interchangeable adj. 可互换的intermediate n. 中间体ion n. 离子isoelectric point n. 等电点isomer n. 异构体Jjacket n. 套, 夹套justification n. 认为正当, 正当的理由Kketone n. 酮Llactic acid n. 乳酸leakage n. 泄漏lesser adj. 较小的, 更少的lime n. 石灰lining n. 衬里, 衬料, 衬套link vt. 连接,键合liquefy vt. 液化lubricating grease n. 润滑脂Mmanipulation n. 操作, 操纵manuscript n. 稿子, 手稿mass spectroscopy n. 质谱mechanism n. 机理, 历程medium n. 介质, 培养基metallurgical adj. 冶金(学)的methane n. 甲烷methnol n. 甲醇methodology n. 方法论micelle n. 胶粒microorganism n. 微生物migrate vi. 迁移miscible adj. 可溶混的modification n. 修饰monomer n. 单体monosaccharide n. 单糖multiplet n. 多重峰multiplicity n 多重性Nnaphthalene n. 萘nitration n. 硝化作用nitric acid n. 硝酸nitrile n. 腈noble adj. 贵重的, 惰性的nomenclacture n. 命名法noteworthy adj. 显著的nucleophile n. 亲核试剂nucleic acid n. 核酸neutralization n. 中和numerator n. (数学上) 分子nutrient n. 营养素, 养分Oobservable a. 可观察到的octane number n. 辛烷值olefin n. 烯烃optical activity n. 旋光性optics n. 光学optimum n. 最佳条件orbital n. 轨道organometallic compound 金属有机化合物originate vi./vt. 起源outermost adj. 最外层的,远离中心的overhead n. 塔顶馏出物overheat vt. 过热overlap vt. 重叠oxidation n. 氧化作用ozonide n. 臭氧化合物ozonolysis n. 臭氧分解Pparaffin n. 链烷烃, 石蜡peptide n. 肽perfume n. 香料peroxide n. 过氧化合物persistence n. 坚持, 固执pesticide n. 杀虫剂pharmaceuticals n. 药物phenol n. 苯酚phenoxide n. (苯)酚盐phenylsulfonic acid n. 苯磺酸phosphoric acid n. 磷酸photochemical reaction n. 光化学反应photochromism n. 光致变色photoconductivity n. 光电导性pigment n. 颜料pink n. 粉红色polyamide n. 聚酰胺polarization n. 极化作用polyhydric alcohol n. 多元醇polymerization n. 聚合作用precipitate vi. /n. 沉淀preservative n. 防腐剂prolong vt. 延长, 拖延propellant n. 推进剂prospective adj. 预期的, 有希望的protecting group n. 保护基purity n. 纯度pyridine n. 吡啶pyrolysis n. 热解pyrrole n. 吡咯Qquantify vt. 使量化,确定数量quaternary ammonium salt n. 季铵盐quench vt. 淬灭quinoline n. 喹啉Rracemization n. 外消旋作用reagent n. 试剂realization n. 实现recover vt. 回收recrystallization n. 重结晶rectifier n. 精馏器reduction n. 还原(作用) reflux n. 回流refract vt. 折射refrigerant n. 冷冻剂remainder n. 剩余物, 残余部分的replica n. 复制品,拷贝resolution n. 分辨, 拆开restrictive adj. 限制性的ribonucleic acid n. 核糖核酸(RNA) rigorous adj. 严厉(格)的Ssaccharin n. 糖精saponification n. 皂化(作用) screen n. 筛子, 屏幕seal n. 密封(垫) segment n. 部分, 链段selectivity n. 选择性settle vt. (使)沉淀, 澄清setup vt. 装置, 装配sewage n. 污水silica gel n. 硅胶singlet n. 单重峰skeleton n. 骨架solubility n. 溶解度solvant n. 溶剂化物solvent n. 溶剂, 有溶解力的sophistication n. 复杂spectroscopy n. 光谱spin-spin coupling n. 自旋-自旋偶合stabilization n. 稳定作用stereoisomerism n. 立体异构现象steric factors n. 位阻因素, 空间因素still pot n.蒸馏釜stoichiometric adj. 化学计算的straightforward adj.一直向前, 正直的substituent n. 取代基substitution reaction n. 取代反应sucrose n. 蔗糖sulfa drug n. 磺胺药sulfonation n.磺化作用sulfuric acid n. 硫酸supervisor n. 导师, 监督人, 主管人suspension n. 悬浮液sweetener n. 增甜剂symmetry n. 对称性symposium n. 座谈会syn addition n. 顺式加成Ttar n. 焦油(沥青)tartaric acid n. 酒石酸tautomerism n. 互变异构现象terpene n. 萜烯tertiary adj. 叔的, 第三的tetrahedron n. 四面体thiazole n. 噻唑thiophene n. 噻吩toluene n. 甲苯toxicity n. 毒性transesterification n. 酯交换反应transition state n. 过渡状态tray n. 盘, 分馏塔盘triplet n. 三重峰trivial adj. 轻微的Uultraviolet-visible spectroscopy n. 紫外-可见光谱unify vt. 统一urea n. 尿素Vvalidate vt. 使生效vaporize vt.蒸发versatile adj. 多方面的vice versa adj. 反之也然vinegar n. 醋violate vt. 破坏,侵害Wwhereas conj. 而, 却, 鉴于withdraw vt. 拉, 提取, 取出withdrawal n. 收回,撤回Xxerography n. 静电复印法Yyeast n. 酵母Zzymochemistry n. 酶化学。
电化学课件-纯英文7Ultramicroelectrodes
EQCM - Principles of Operation
• Solution exerts a dampening effect:
– Under potential control – XPS, SEM, etc. not in situ
• Very sensitive
– Good for complex matrices
• Physiological fluids
• Detection limit
– pmole - fmole
ele–ctr2odeelectrodes sandwiching quartz (piezoelectric)
Quartz cry• sotaslcillating E surface of quartz wafer • oscillation at characteristic frequency (2 - 20 MHz)
• Stray capacitance
– Impurities
• Maintenance
– Cost – Fragile construction
UME’s - Applications
• Determine [analyte] • Study reactions
– at low temperatures = frozen glasses
• Biological systems
– Single cells – organelles
• Fast kinetics • Development of analytical tools for
紫外吸收光谱分析UVPPT课件
当取代基上具有的非键电子的基团与苯环的π电子体系共轭相 连时,无论取代基具有吸电子作用还是供电子作用,都将在不同 程度上引起苯的E2带和B带的红移。
当引入的基团为助色基团时,取代基对吸收带的影响大小与 取代基的推电子能力有关。推电子能力越强,影响越大。顺序为 -O->-NH2>-OCH3>-OH>-Br>-Cl>CH3
2.3.1 概述
紫外-可见吸收光谱(Ultraviolet and Visible Spectroscopy, UV-VIS)统称为电 子光谱。
紫外-可见吸收光谱法是利用某些物质的分子吸 收200~800nm光谱区的辐射来进行分析测定的 方法。这种分子吸收光谱产生于价电子和分子轨道 上的电子在电子能级间的跃迁,广泛用于有机和无 机物质的定性和定量测定。
图2.23 紫外—可见吸收曲线
3
2.3.2 紫外吸收光谱的基本原理
1 电子跃迁类型
(1)σ→σ* 跃迁 指处于成键轨道上的σ电子吸收
光子后被激发跃迁到σ*反键轨道
(2)n→σ* 跃迁 指分子中处于非键轨道上的n电
子吸收能量后向σ*反键轨道的跃迁
(3)π→π* 跃迁 指不饱和键中的π电子吸收光波
能量后跃迁到π*反键轨道。
9
iii B—带 B带(取自德文:benzenoid band, 苯型谱带)。它
是芳香族化合物的特征吸收带。是苯环振动及π→π*
重叠引起的。在230~270nm之间出现精细结构吸收, 又称苯的多重吸收,如图2.20。 iv E-带 E带(取自德文:ethylenic band,乙烯型谱带)。 它也是芳香族化合物的特征吸收之一(图2.25)。E带 可分为E1及E2两个吸收带,二者可以分别看成是苯环
对位—OCH3取代 +25
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When continuous radiation passes through a transparent material, a portion of the radiation may be absorbed. If that occurs, the residual radiation, when it is passed through a prism, yields a spectrum with gaps in it, called an absorption spectrum. As a result of energy absorption, atoms or molecules pass from a state of low energy (the initial, or ground state) to a state of higher energy (the excited state).
For most molecules, the lowest-energy occupied molecular orbitals are the σ orbitals, which correspond to σ bonds. The π orbitals lies at somewhat higher energy levels, and orbitals which hold unshared pairs, the nonbonding (n) orbitals, lies at even higher energies. The unoccupied, or antibonding orbitals (π* and σ*), are the orbitals of highest energy.
azo 含氮的
quantum 量子,量子论
symmetry 对称,匀称
theoretical 理论的
approximate 近似的,大约的
spectrophotometer 分光光度计
fluorescent 荧光的
monochromator 单色器,单色仪 deuterium 氘
tungsten 钨
The electromagnetic radiation which is absorbed has energy exactly equal to the energy difference between the excited and ground states.
In the case of ultraviolet and visible spectroscopy, the transitions which result from the absorption of electromagnetic radiation in this region of the spectrum are transitions between electronic energy levels. As a molecule absorbs energy, an electron is promoted from an occupied orbital to an unoccupied orbital of greater potential energy. Generally, the most probable transition is from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). The energy differences between electronic levels in most molecules vary from 125 to 650 kJ/mol (kilojoules per mole).
Not all of the transitions which at first sight appear possible are observed. Certain restrictions, called selection rules, must be considered. One important selection rule states that transitions which involve a change in the spin quantum number of an electron during the transition are not allowed to take place; they were called ‘forbidden’ transitions. Other selection rules deal with the numbers of electrons which may be excited at one time, with symmetry properties of the molecule and of the electronic states, and with other factors which need not be discussed here. Transitions that are formally forbidden by the selection rules are often not observed. However, theoretical treatments are rather approximate, and in certain cases forbidden transitions are observed, although the intensity of the absorption tends to be much lower than for transitions which are allowed by the selection rules. The n→π* transition is the most common type of forbidden transition.
2. The Origin of UV Band Structure
For an atom which absorbs in the ultraviolet, the absorption spectrum often consists of very sharp lines, as would be expected for a quantized process occurring between two discrete energy levels. For molecules, however, the UV absorption usually occurs over a wide range of wavelengths, because molecules (as opposed to atoms) normally have many excited modes of vibration and rotation at room temperature. In fact, the vibration of molecules cannot be completely ‘frozen out’ even at absolute zero. Consequently, a collection of molecules generally has its members in many states of vibrational and rotational excitation. The energy levels for these states are quite closely spaced, corresponding to energy differences considerably smaller than those of electronic levels. The rotational and vibrational levels are thus ‘superimposed’ on the electronic levels. A molecule may therefore undergo electronic and vibrational-rotational excitation simultaneously.
hyperchromic effect 增色效应
hypochromic effect 减色效应
Most organic molecules and functional groups are transparent in the portions of the electromagnetic spectrum which we call the ultraviolet (UV) and visible (VIS) regions-that is, the regions where wavelengths range from 190 nm to 800 nm. Consequently, absorption spectroscopy is of limited utility in this range of wavelengths. However, in some cases we can derive useful information from these regions of the spectrum. That information, when combined with the detail provided by infrared and nuclear magnetic resonance spectra, can lead to valuable structure there are so many possible transitions, each differing from the others by only a slight amount, each electronic transition consists of a vast number of lines spaced so closely that the spectrophotometer cannot resolve them. Rather, the instrument traces an ‘envelope’ over the entire pattern. What is observed from these types of combined transitions is that the UV spectrum of a molecule usually consists of a broad band of absorption centered near the wavelength of the major transition.