It's estimated that for every 10,000 bills in the U.S., one of those bills is fake.
在美国，大约每一万张纸币里就有一张是假币。
That may not sound like much, but it adds up to millions of dollars in cold hard cash.
这听起来可能不多，但加起来能有几百美金的现金。
Counterfeit money has the potential to cause all sorts of problems,
假币可能带来种种问题，
from leaving you short $20 to destabilizing national economies.
小至让你少二十美金，大至让国家经济瘫痪。
But don't worry. You can help catch the counterfeits.
但不要担心。出售中你可以帮忙识别这些假币。
All you need are some simple tools and a bit of chemistry.
而做到这些，你只需一些小道具和一点化学物质。
First up, the anti-counterfeit detection pen.
首先，是这根防伪探测笔。
The pen looks like a highlighter and contains a solution of potassium iodide and elemental iodine.
这笔看起来像是根记号笔，它里面还有碘化钾溶液以及碘单质。
It reveals of the presence of starch,
它可以检测淀粉是否存在，
which is commonly used to strengthen regular printer paper, but won't be found in real money.
而淀粉常用于加强常规印刷纸张，但是，真钞中并不会用到。
That's because authentic bills are made of cotton and linen and are threaded with tiny red and blue fibers.
因为，真钞使用棉花和亚麻制成，并由细小的红蓝纤维编织而成。
That material is made by a single, highly-guarded company called Crane and Company,
这种材料是由一家专门的、受到严密保护的公司制成，公司名为克兰公司，
which has been printing currency since Paul Revere asked them to help finance the Revolutionary War.
它自独立战争起就收到保罗·里维尔希望它拯救经济的请求，从而开始印刷货币。
The starch in many counterfeit bills, on the other hand, is made of two molecules: amylopectin and amylose.
而假币里的淀粉由两种分子组成：支链淀粉和直链淀粉。
It's amylose that gives the fake away.
而让假币露馅的是直链淀粉。
Its long chain of sugar molecules connected by oxygen atoms forms a helical structure, like DNA.
由氧原子相连的长链多糖分子形成了如DNA的螺旋结构。
Iodide likes to squeeze inside this coil, forming a new compound that leaves a dark mark on the paper.
碘元素常钻进这个螺旋管内部，从而形成一种可以在纸张上显现深色的新混合物。
However, in the absence of starch, there is no chemical reaction and the mark will look light yellow.
但如果不含淀粉，就不会有化学反应产生，笔迹仍将是浅黄色。

So if the fake isn't printed on starchy paper, iodine solutions can't help you.
如果假币不是用含淀粉的纸张制造的，碘溶液就帮不了你了。
That's one of the reasons U.S. bills printed since 1996 have been chemically enhanced
这也是为什么自1996年起美金纸币从化学层面上进行了加强，
to include another counterfeit countermeasure: a strip that fluoresces under UV light.
从而有了另一种鉴别假币的方法：一条在紫外线下会发荧光的印记。
That's the same kind of light used at black light parties and airport security lines.
这种光也就是在黑光派对及机场安检时用的灯光。
The polyester strip printed with invisble ink is just one millimeter wide
印有隐形墨水的涤纶条只有一毫米宽，
and is found in different positions depending on a bill's value.
并会因纸币面值大小的差异，而设置在不同位置。
If you hold your dollar up to natural light, you can see the amount and the word USA printed on the band.
如果你把纸币放在自然光下看，你能看到涤纶条上印刷的USA和纸币面值。
But under UV light, these strips really shine.
在紫外线光线下，这些涤纶条会变得很亮。
They contain molecules that can be excited by absorbing certain amounts of energy,
它们包含可以通过吸收一定程度的能量来激发自己的分子，
specifically, that given off by common UV light sources.
特别是普通紫外线光源发出的能量。
As these excited molecules return to their original states,
在这些激发态分子变回基态的过程中，
they lose a bit of energy as heat and then radiate the rest as light.
它们损失的能量先是以热能形式排出，剩下的则以光能排出。
Energy is inversely related to wavelength, which means that the longer wavelengths have lower energy.
能量与波长呈反相关，既波长越长，所持有的能量越少。
So the lower energy light given off by the strip means longer wavelengths that fall in the visible range,
所以涤纶条发出低能量光线时，肉眼可观察的长波长光线出现，
and suddenly we can see that which had been invisible.
于是我们突然能看到这些曾经看不到的光线。
And if a glowing strip doesn't show up on a recent bill, you have a fake on your hands.
如果你最近收到的现金中并没有这条发光的印记，那么你收到假币了。
For times when you're not dealing with counterfeit masterminds, looking for simple visual cues will do.
在你并没有直接与假币制造商打交道时，你可以找一些简单的视觉线索。
Make sure the portrait looks lifelike and not flat,
确定画像看起来逼真且不扁平，
the seal has perfectly even sawtooth points, the inked border is unbroken,
印章的齿状边缘整齐完美，墨水没有印刷出界，
and the serial number has precisely equal spacing between each number.
以及序列号的每个数字间距离一样。
So the next time you come across some dubious dough, have a closer look,
下次你再遇上有些可疑的纸币时，仔细看看它，
pull out your iodine solution, or take it to a rave and you just might catch a counterfeit.
拿你的碘溶液试试，或带着它去家夜店，你或许会发现它是张假币。