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托福听力讲座:光谱学

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2018-05-30 10:27

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  托福听力讲座考试涉及的范围比较广,对于同学们来说是比较难的,那么下面就和出国留学网的小编一起来看看托福听力讲座:光谱学。

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  Introduction:

  Spectroscopy

  复色光经过色散系统(如棱镜、光栅)分光后,被色散开的单色光按波长(或频率)大小而依次排列的图案,全称为光学频谱。光谱中最大的一部分可见光谱是电磁波谱中人眼可见的一部分, 在这个波长范围内的电磁辐射被称作可见光。光谱并没有包含人类大脑视觉所能区别的所有颜色,譬如褐色和粉红色。

  Background information:

  Spectroscopy and spectrography are termsused to refer to the measurement of radiation intensity as a function ofwavelength and are often used to describe experimental spectroscopic tral measurement devices are referred to as spectrometers,spectrophotometers, spectrographs or spectral analyzers.

  Daily observations of color can be relatedto spectroscopy. Neon lighting is a direct application of atomic  and other noble gases have characteristic emission frequencies (colors) lamps use collision of electrons with the gas to excite these , dyes and paints include chemical compounds selected for their spectralcharacteristics in order to generate specific colors and hues. A commonlyencountered molecular spectrum is that of nitrogen dioxide. Gaseous nitrogen dioxidehas a characteristic red absorption feature, and this gives air polluted withnitrogen dioxide a reddish brown color. Rayleigh scattering is a spectroscopicscattering phenomenon that accounts for the color of the sky.

  Spectroscopic studies were central to thedevelopment of quantum mechanics and included Max Planck's explanation ofblackbody radiation, Albert Einstein's explanation of the photoelectric effectand Niels Bohr's explanation of atomic structure and spectra. Spectroscopy isused in physical and analytical chemistry because atoms and molecules haveunique spectra. As a result, these spectra can be used to detect, identify andquantify information about the atoms and molecules. Spectroscopy is also usedin astronomy and remote sensing on earth. Most research telescopes havespectrographs. The measured spectra are used to determine the chemicalcomposition and physical properties of astronomical objects (such as theirtemperature and velocity).

  Knowledge points:

  1. 光谱学是指测量作为波长的辐射强度,它经常被用来描述实验光谱方法。

  2. 二氧化氮是一种常用的分子光谱。气态的二氧化氮具有吸收红色的特征,因此被二氧化氮污染的空气呈现红褐色。

  3. 光谱可以用来确定物体的化学成分和物理特性。

  Vocabulary prediction:

  Substance 物质

  Spectroscopy 光谱学

  Zinc 锌

  Pigment 颜料

  Test Point – TPO5L3

  What is Spectroscopy? Well, the simplestdefinition I can give you is that Spectroscopy is the study of the interactionbetween matter and light. Now, visible light consists of different colors orwavelengths, which together make up what's called spectrum, a band of colors,like you see in a rainbow. And all substances, all forms of matter, can be distinguishedaccording to what wavelength of light they absorb and which ones they 's like, m, well, every element has, what we call, its own spectralsignature. If we can read that signature, we can identify the element. Andthat's exactly what spectroscopy does.

  Now, Laser Spectroscopy, which is the focusof your assignment, works by measuring very precisely what parts of thespectrum are absorbed by different substances. And it has applications in a lotof different disciplines. And your assignment will be to choose a disciplinethat interests you, and devise anexperiment.

  Knowledge points

  1.最简单的对光谱学的理解是,光谱学是研究物体和光的相互作用的学科。可见光是由不同颜色的波长组成的,这些合起来叫做光谱,像我们看到的彩虹一样,有不同的颜色。

  2.所有形式的物质可以根据它们对不同波长的光的吸收和反射来被区分。每一个元素都有它特有的光谱特征。我们可以通过不同的光谱特征来辨别不同的物质。

  推荐阅读:

  托福听力:态度题

  托福听力词汇:经济学类

  托福听力背景知识:动物学

  托福听力素材:现代生物学

  想了解更多托福听力网的资讯,请访问: 托福听力

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