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Listen to part of a lecture in a chemistry class.
請聽化學課上的一篇演講
Okay.
好的，
I know you all have a lot of questions about this lab assignment that's coming out so I 'm going to take a little time this morning to discuss it.
我知道你們對此次的實驗作業都有很多問題，因此今天早上我將花點時間跟你們討論一下。
So, you know the assignment has to do with Spectroscopy, right?
那么，你們知道此次作業是跟光譜學有關的，是吧？
And your reading should help you get a good idea of what that's all about.
你們通過閱讀應該能夠很好了解這個概念。
But, let's talk about Spectroscopy a little now just to cover the basics.
但是，我們還是將一些光譜學的基本要點過一遍吧。
What is Spectroscopy?
什么是光譜學呢？
Well, the simplest definition I can give you is that Spectroscopy is the study of the interaction between matter and light.
嗯，我能給你們的最簡單的定義就是，光譜學是關于物和光之間相互作用的研究。
Now, visible light consists of different colors or wavelengths, which together make up what's called spectrum,a band of colors, like you see in a rainbow.
光譜是一條五顏六色的緞帶，就像你看到的彩虹一樣。
And all substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect.
而所有的物質和物質形式都可以根據其吸收的光的波長和其反射的光來加以區分。
It's like, um, well, every element has, what we call, its own spectral signature.
它就像，嗯，什么元素都有，我們所說的，它本身的光譜簽名。
If we can read that signature, we can identify the element.
如果我們可以讀懂，我們就可以知道是什么元素。
And that's exactly what spectroscopy does.
這正是光譜學的作用所在。
Now, Laser Spectroscopy, which is the focus of your assignment, works by measuring very precisely what parts of the spectrum are absorbed by different substances.
激光光譜學是你們作業中的重點，它能非常精確地測量光譜中哪一部分被不同的物質吸收。
And it has applications in a lot of different disciplines.
該門學科在不同學科中有所應用。
And your assignment will be to choose a discipline that interests you, and devise an experiment.
你們的任務就是要選擇一門你感興趣的學科然后進行實驗。
For example, I 'm going to talk about art.
比如說，我要談談關于藝術這門課。
I 'm interested in the art and to me it's interesting how spectroscopy is used to analyze art.
我對藝術很有興趣，我對光譜學是怎么應用在對藝術的分析上的問題感興趣。
Er ... let's say a museum curator comes to you with a problem.
呃。比如一位博物館館長帶著問題走向你。
She's come across this painting that appears to be an original - let's say,a Rembrandt.
比如說，她碰到一幅貌似是真跡的油畫，出自倫勃朗之手。
And she wants to acquire it for her museum.
她想收購這幅畫放到博物館中去。
But she's got a problem: she's not absolutely certain it's an original.
但她有一個問題：她不是很確定這是否為真跡。
So, what do you do?
那么你怎么做呢？
How do you determine whether the painting's authentic?
你怎么判定這幅畫是真跡呢？
Okay.Think about the scientific process.
好的，想想科學的方法。
You 've got the question: Is the painting a Rembrandt?
你現在的問題是：這幅畫是倫勃朗畫的嗎？
So first, you 'll need to make a list of characteristics the painting would have to have to be a Rembrandt.
那么首先，你將需要列出這幅畫具有的倫勃朗畫作的特征。
Then you have to discover whether the painting in question has those characteristics.
然后你必須看這幅有爭議的畫是不是有這些特征。
So first of all, you 'll need to know the techniques Rembrandt used when he applied paint to canvas - his brushstrokes,
首先，你要了解倫勃朗在帆布上畫畫時會使用的技巧，他的畫風，
how thickly he applied his paint.
他用的顏料的情況。
So you 'd need to work with an art historian who has expert knowledge of Rembrandt's style.
那么你要請教一名對倫勃朗畫風有專業了解的藝術歷史學家。
You 'd have to know when he created his paintings, um ... what pigments he used,
你要知道他什么時候創作，嗯，用什么顏料創作，
in other words, what ingredients he used to make different colors of paint, cos the ingredients used in paints and binding agents plus varnishes,
換句話說，就是他使用什么材料畫出不同的顏色，因為繪畫中使用的
finishes, what have you, have changed over time.
顏料和粘合劑會隨著時間而改變。
Since you 're trying to verify that's a Rembrandt, the ingredients in the pigment would need to have been used during Rembrandt's lifetime - in the 17th century.
由于你試圖證明這是倫勃朗的真跡，其顏料中使用的材料就必須是倫勃朗那個年代，即十七世紀，所使用過的顏料。
And that's where chemistry comes in.
這是就需要用到化學知識了。
You 've got to find out what's in those pigments, learn their composition, and that requires lab work - detective work really - in a word,
你要了解顏料的成分，而這需要做實驗，探測性實驗，才能得知，
Spectroscopy.
這就是光譜學。
So, how do we use Spectroscopy?
那么我們怎么利用光譜學呢？
Well, we put an infrared microscope - a spectroscope - on tiny tiny bits of paint.
嗯，我們使用紅外線顯微鏡，一個分光鏡，來觀察油畫上很小很小的部分。
And using ultraviolet light we can see the spectral signature of each component part of the pigment.
使用紫外線，我們可以看到顏料上每一部分的光譜簽名。
Then we compare these signatures with those of particular elements like zinc or lead, to determine what the pigment was made of.
然后我們將這些簽名符號和一些特別的元素，鋅和鉛，來判定顏料是什么組成的。
So, you can see why this type of analysis requires a knowledge of the history of pigments, right?
這樣，你就知道為什么這種研究需要關于顏料使用史的知識了對吧？
How and when they were made?
他們怎么制成何時制成的呢？
Say we determined a pigment was made with zinc, for example.
比如我們判定某一種顏料是由鋅構成的。
We know the spectral signature of zinc.
我們知道鋅的光譜簽名，
And it matches that of the paint sample.
它和顏料樣本相符合。
We also know that zinc was not discovered until the 18th century.
我們也知道直到18世紀鋅才被發現。
And since Rembrandt lived during the 17th century, we know he could not have painted it.
而倫勃朗生活在十七世紀，我們知道他是不可能用鋅來作畫的。
Now, Spectroscopy has a very distinct advantage over previous methods of analyzing our works, because it's not invasive.
現在，光譜學比起以前的解析作品的方法優異更為明顯，因為它不不會對原作造成損害。
You do not have to remove big chips of paint to do your analysis, which is what other methods require.
你不需要移動一部分油畫來進行分析，而其他方法是必須的。
All you do is train the microscope on tiny flecks of paint and analyze them.
你所做的就是；練習使用顯微鏡對準油畫上的小小斑點，進行分析。
Now a word or two about restoration.
現在簡單講講儲藏方法。
Sometimes original art works appear questionable or inauthentic because they 've had so many restorers add touchup layers to cover up damage,
有時候藝術品真跡看起來是贗品是因為很多修護人員加上很多層保護膜覆蓋油畫上的損害。
damage from the paint having deteriorated over time.
畫作上損壞的地方經久日衰。
Well, spectroscopy can review the composition of those touchup layers too.
而光譜學也可以顯示出這一層附加上去的物質成分。
So we can find out when they were applied.
我們因此可以知道是什么時候加上去的一層東西。
Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original.
而如果我們想避免一些錯誤的修復嘗試，我們能通過判定修復過程中哪一步會溶解畫作和掩蓋真跡的痕跡。
