光谱学_文献翻译

英文原文：
Spectroscopy
Isaac Newton showed that a glass prism could be used to split sunlight into a spectrum in 1666. Further studies by William Wollaston in 1802 revealed some black lines on the component colors of the solar spectrum. More detailed observations by Joseph von Fraunhofer resulted in 574 of these lines being mapped by 1815. These lines were named "Fraunhofer lines" in his honor. The image below shows a solar spectrum with Fraunhofer lines. Fraunhofer lines are dark absorption lines in the solar spectrum that can be seen when sunlight is passed through a prism to separate it into the colors of the rainbow. They occur because cooler gas, which is higher in the Sun's atmosphere, absorbs some colors of the light emitted by hotter gas lower in the Sun's atmosphere.
Two key questions arise from studying these lines--what do they represent and how are they formed? The solutions to these questions were to take some time. Leon Foucault matched the lines produced by a sodium lamp with some of the dark lines in a solar spectrum in 1849. In 1857 Gustav Kirchoff and Robert Bunsen identified sodium in a solar spectrum. They found that a luminous solid or highly compressed hot gas could produce a continuous spectrum whilst a diffuse hot gas produced a spectrum with narrow bright lines on a black background.
Spectroscopy was originally the study of the interaction between radiation and matter as a function of wavelength. In fact, historically, spectroscopy referred to the use of visible light dispersed according to its wavelength, e.g. by a prism. Later the concept was expanded greatly to comprise any measurement of a quantity as function of either wavelength or frequency. Thus it also can refer to a response to an alternating field or varying frequency. A further extension of the scope of the definition added energy as a variable, once the very close relationship E=ℎνfor photons was realized. A plot of the response as a function of wavelength – or more commonly frequency – is referred to as a spectrum.
Spectrometry is the spectroscopic technique used to assess the concentration or amount of a given species. In this case, the instrument that performs such measurements is a spectrometer or spectrograph. Spectroscopy or spectrometry is often used in physical and analytical chemistry for the identification of substances through the spectrum emitted from or absorbed by them. It is also heavily used in astronomy and remote sensing. Most large telescopes have spectrometers, which are used either to measure the chemical composition and physical properties of astronomical objects or to measure their velocities from the Doppler shift of their spectral lines.
Two general types of spectra are now known, the continuous spectrum and the line spectrum. The continuous spectrum shows all the component colors of the rainbow. Line spectra appear in two forms, absorption spectra, showing dark lines on a bright background, and emission spectra with bright lines on a dark or black background. The first are like the solar spectrum and those from stars and the second are like those emitted from gas discharge tubes and some nebulae. These two types are in fact related and arise
due to quantum mechanical interactions between electrons orbiting atoms and photons of light. Photons of light each have a specific frequency. The energy of a photons is a function of its frequency and is determined by E=ℎν, where νis the frequency of the photon, E is the energy and ℎis Planck's constant which is equal to 6.626×10−34J∙s.
An electron orbits a nucleus in a stable energy level. If a photon of a specific frequency interacts with the electron, it can gain sufficient energy to "jump up" one or more levels. The photon is absorbed by the electron so cannot continue on to be detected by an observer. The electron then "de-excites" and jumps back down to a lower energy orbit, emitting a photon of specific frequency. This photon, however, could be emitted in any direction, not just in the same direction as the original incident photon. This is sown schematically in the diagram Fig.30-2.
The Swiss school teacher, Johann Balmer in 1885 developed an empirical formula that determined the wavelengths of the four visible lines in hydrogen's spectrum. Five years later the Swedish physicist, Johannes Rydberg expanded Balmer's formula to apply to some other elements. The Danish physicist, Niels Bohr, finally provided an explanation as to how spectral lines formed in the 1920s.His work relied on quantum physics and the concept of energy shells or orbits for electrons.
The Balmer Series of visible lines for atomic hydrogen are caused by transitions from the n=2orbit to and from higher orbits. The Lyman Series involves transitions down to the n=1orbit and involve higher frequency photons in the UV region whilst the Paschen Series (to n=3) produces IR spectral lines. The number of spectral lines that can be produced is vast given the permutations of atoms, molecules and orbital transitions possible.
中文译文：
光谱学
1666年，艾萨克·牛顿发现可以用玻璃棱镜把太阳光转换成一个光谱。

1802年，威廉·沃拉斯顿在进一步研究后发现在太阳光的光谱中存在一些暗线。

而1815年，约瑟夫•冯•夫琅和费在通过更详细的观察确定了其中的574条暗线。

这些线条也因此被命名为“夫琅禾费线”。

下面的图片显示了一个包含光谱线太阳光谱。

夫琅和费谱线是深色太阳光谱的吸收线,在阳光通过棱镜来分离成七色光时可以被看到。

它们出现是因为太阳大气层内层高温气体发出的一些彩色光线被太阳大气层外层的低温气体吸收所致。

在研究这些暗线时有两个关键问题——它们代表什么？它们是如何形成的？对这些问题的解决都需要一些时间。

1849年，莱昂·傅科将钠黄光中的暗线条与太阳能光谱的暗线做了匹配。

1857年, 古斯塔夫•基尔霍夫和罗伯特·本生在太阳能光谱中发现钠。

他们发现发光的固体或高压热气体可以产生连续光谱，而扩散的热气体可以在黑色背景上产生窄亮线光谱。

光谱学最初是用来研究与波长有关的辐射与物质之间的相互作用。

事实上,从历史上看,光谱学被用在比如用棱镜将可见光的不同波长光波分开。

后来这个概念被扩大到包括对任何基于波长或频率的值的测量。

因此它也可以反映交变磁场或变化的频率。

进一步扩展的定义中将能量作为一个条件,建立起能量与光子之间的关系E=ℎν。

一些取决于不同波长或频率的图案，称为光谱。

光谱测量是一门用于对给定条件测量浓度或数量的光谱技术。

用于光谱测量的仪器称为光谱仪或摄谱仪。

光谱学和光谱测量常用于物理学和分析化学中，通过物质辐射或者吸收的光波来识别物质的成分。

它们也大量用于天文学和遥感。

大多数大型望远镜都有光谱仪,用以测量天体的化学成分和物理性质或通过谱线的多普勒频移测量他们的速度。

现已知光谱的两种常规类型是连续光谱和线光谱。

连续谱在色带上显示出所有的成分色光。

线光谱有两种形式，出现在明亮背景上的暗线为吸收光谱, 出现在深色背景上的明线为发射光谱。

比如太阳光谱和那些来自恒星的光谱属于吸收光谱，而气体辐射的光线放电管和一些星云属于发射光谱。

这两种类型事实上有内在联系，都是由于电子轨道原子和光子之间的量子力学相互作用产生的。

每个光子都有一个
特定的频率。

一个光子的能量由频率确定,关系为E=ℎν，其中ν是光子的频率,E是能能量，ℎ是普朗克常数，值为6.626×10−34J∙s。

电子绕核在一个稳定的能量级运动。

如果一个特定的频率光子与电子相互作用，电子就可以获得足够的能量来“跃迁”一个或多个能级。

光子被电子吸收,因此无法监测到。

电子获得能量后“发光”并跃迁到一个低能量轨道,发射出特定频率的光子。

而起方向可以是任意的,不局限于与原入射光子同向。

传播如图30-2所示。

一位瑞士的学校老师约翰·巴尔默在1885年发现一个经验公式用来确定氢光谱四条谱线的波长。

五年后瑞典物理学家约翰内斯·里德伯扩展了巴尔默公式使其适用于一些其他元素。

丹麦物理学家尼尔斯·波尔,最后于18世纪20年代提出了一个关于谱线是如何形成的的解释。

他的结论来源于量子物理和能量壳(或者说是轨道电子)的概念。

氢原子可见谱线的巴尔末系是由电子从n=2的能级往更高能级跃迁产生的。

莱曼系包括向n=1能级的跃迁的光子和紫外光区域内更高频率的光子,而帕邢系(往n=3能级跃迁)会产生红外谱线。

大量的红外谱线使原子排列,分子和轨道跃迁成为可能。

09级应用物理
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