经济学人下载:绯红色(2)

As it happens, rubies are one of Dr Subramanian's inspirations.
碰巧，红宝石是Subramanian博士的灵感之一。

His hope is that by piggybacking on the structure of their crystals—
他希望借助它们晶体的结构—

already known to yield an appropriately, well, ruby, colour—he might be able to reproduce the effect.
已知能够产生适当的红宝石色—他也许能重现这种效果。

A weakness of this approach is that rubies themselves make an unsatisfactory pigment. When crushed, they become pale pink.
这种方法的一个弊端在于红宝石本身不能产生令人满意的色素。当它们被压碎时，就会变成淡粉色。

A second avenue may be more promising. Many inorganic reds, including those based on cadmium, lead and mercury, are semiconductors.
第二种方法或许更有希望。很多无机红色，包括那些基于镉、铅和汞的红色都是半导体。

Dr Subramanian and his team hope to use tin—a metal in the same group of the periodic table as lead—
Subramanian博士和他的小组希望利用锡—一种在周期表中和铅属同一组的金属—

to produce a similarly vibrant, though non-toxic, semiconductor pigment.
生产一种同样鲜艳但无毒的半导体色素。

Inevitably, the semiconductor approach does bring problems of its own.
半导体方法本身也会带来不可避免的问题。

A semiconductor's colour depends on a phenomenon called its band gap. This is the ease with which its atoms can shed electrons.
一个半导体的颜色取决于一种被称为带隙的现象，因此它的原子可以轻易地释放电子。

The process of shedding requires energy, often in the form of light,
脱落的过程需要能量，通常以光的形式

so a substance's band gap helps determine which frequencies of light it absorbs and which it reflects.
因此，物质的带隙有助于确定它吸收和反射的光的频率。

Unfortunately, band gaps can, themselves, be altered by exposure to energy in the form of heat or light. That changes the pigment's colour.
不幸的是，带隙本身可以通过暴露于热或光形式的能量中而改变。这就改变了色素的颜色。

For example, mercury sulphide, known to painters as vermilion, has a small band gap.
例如，硫化汞，被画家称为朱红色，有一个小的带隙。

This means it absorbs much of the visible spectrum, reflecting only red because red light is insufficiently energetic to shift the relevant electrons.
这意味着它吸收了大部分可见光谱，只反射红光，因为红光的能量不足以转移相关的电子。

If the gap is diminished still more, as sometimes happens when vermilion is exposed to light,
如果带隙进一步缩小，就像有时朱红色暴露在阳光下所发生的那样

the pigment absorbs all visible light and turns black. Making a semiconducting red is not enough, then.
色素会吸收所有可见光并变成黑色。因此，制造半导体红色是不够的。

It also needs to stay red when in use. And that essential property remains elusive.
它还需要在使用过程中保持红色。而这一基本属性仍然难以捉摸。

Dr Subramanian and his team have got close. The tin approach has resulted in some promising flame-bright superconducting oranges.
Subramanian博士而他的小组已经接近成功。锡方法已经产生了一些有希望的鲜如火焰的超导橘色。

But shrinking the band gaps of such materials just that little bit further, to the point where a brilliant red is reflected instead,
但进一步缩小这种材料的带隙直到反射出明亮的红色

has so far proved beyond their chemical skills.
到目前为止，他们的化学技能还无法证明。