A new sort of solar cell is in the making
INFRA-RED light has not featured high on the list of alternative sources of energy. Solar cells prefer visible, or even ultraviolet radiation. But there is a lot of infra-red in the spectrum, so it seems silly to ignore it. Steven Novack, of the Idaho National Laboratory in America has therefore been looking for ways to capture it-and, as he told a meeting earlier this month in Jacksonville, Florida, held by the American Society of Mechanical Engineers, it looks as though he has found one.
Solar cells work because visible and ultraviolet light are powerful enough to knock electrons free from atoms. The electrons go on to form a useful direct current. Infra-red is not powerful enough to do this. It is, however, powerful enough to set electrons vibrating-particularly those electrons already floating free inside a metallic crystal lattice. Design a structure in which the electrons resonate in a way analogous to a tuning fork and you have a type of generator, since the resonating electrons are, in effect, an alternating current. Indeed, that is how a radio antenna works, except that the weak current generated by the radio waves has to be amplified to do its job of carrying a signal round a radio. Dr Novack, by contrast, proposes to create a current strong enough to be tapped as a source of power.
He and his colleagues designed their infra-red antennae using data they collected while studying how metals behave when exposed to infra-red rays. They tweaked the composition, shape and size of the antennae until they arrived at spiral structures a few nanometres (billionths of a metre) across. The key to commercialising this idea is that such antennae can be stamped by the billion on to plastic sheets. The stamps themselves are made by etching silicon wafers using the technique that makes microprocessors, and the sheets can be shaped to coat anything from cars to portable electronic devices.
The remaining hurdle, admittedly a high one, is to collect the current from the antennae. The usual way to do this would be to use a rectifier-a device that converts alternating to direct current. However, the current in the nanoantennae oscillates at a rate of trillions of cycles a second, which is beyond the range of existing rectifiers. What is needed are smaller rectifiers which would, by very dint of their size, rectify current of an appropriatefrequency.
If that could be done, a new type of solar cell would be available. And not just solar. All hot objects give off infra-red. If you put such a cell next to, say, an engine's exhaust pipe, you would have the ultimate form of recycling.
一种新型太阳能电池呼之欲出
红外线在能源的各种替代来源中并不是那么引人瞩目。太阳能电池更倾向靠可见光，甚至是紫外线来发电。可是，在光频谱中存在大量的红外线，所以，忽略它似乎就有些不明智了。美国爱达荷州国家实验室的史蒂文.纳瓦克（Steven Novack）也就因此一直在寻找各种方法利用红外线来发电-从本月上旬在美国机械工程师学会于佛罗里达杰克逊维尔召开的会议上他透露的情况看，他似乎已经找到了一种方法。
太阳能电池能发电，是因为可见光和紫外线有足够的能量使电子挣脱原子的束缚。这些电子移动就形成了可供使用的直流电。红外线却不具备足够的能量引发这一过程。不过，它的能量足以引发电子产生振动-特别是那些金属晶格内的自由漂浮电子。设计一个结构使电子以类似音叉的方式发生共振，这样你就等于有了一种发电机，因为发生共振的电子从效果看就是一种交流电。事实上，这就是无线天线的工作方式，唯一的区别是这里不需要对无线电波产生的微弱电流要进行放大处理，来让无线电波携带要传输的信号。通过对比，纳瓦克（Novack）博士打算利用这一原理来生产足以用作供电来源的较强电流。
他和同事曾对各种金属在红外线照射下表现出的特性进行了研究，他们利用研究时收集的数据设计了红外线天线组。他们改进天线组的结构、形状和大小，直到最后采用了一些几纳米（十亿分之一米）宽的螺旋结构。这一设计商业化的关键是这种天线组要能够以数以万计的数量贴到塑料片上。这些贴片自身是由蚀刻硅片制成，而硅片用到了制造微处理器时所使用的技术，可以做成各种形状覆盖到从小汽车到便携电子设备的任何产品上。剩下的障碍客观地讲也比较困难，那就是从这些天线组收集电流。完成这步常用的方法是使用整流器-一种把交流电转换成直流电的器件。不过，纳米天线中的电流以每秒上亿个周期的速率振荡，这超出了现有整流器的工作范围。我们需要的是比较小的整流器，正是凭藉它们较小的尺寸，来对相应频率的电流进行整流。
如果这步得以实现，我们就会得到一种新型太阳能电池。所有发热物体都发射出红外线。如果你把这样的电池靠近比如说引擎排气管类的（发热）物体，就实现了废物利用的终极形式。
关键字:双语新闻
生词表:
INFRA-RED light has not featured high on the list of alternative sources of energy. Solar cells prefer visible, or even ultraviolet radiation. But there is a lot of infra-red in the spectrum, so it seems silly to ignore it. Steven Novack, of the Idaho National Laboratory in America has therefore been looking for ways to capture it-and, as he told a meeting earlier this month in Jacksonville, Florida, held by the American Society of Mechanical Engineers, it looks as though he has found one.
Solar cells work because visible and ultraviolet light are powerful enough to knock electrons free from atoms. The electrons go on to form a useful direct current. Infra-red is not powerful enough to do this. It is, however, powerful enough to set electrons vibrating-particularly those electrons already floating free inside a metallic crystal lattice. Design a structure in which the electrons resonate in a way analogous to a tuning fork and you have a type of generator, since the resonating electrons are, in effect, an alternating current. Indeed, that is how a radio antenna works, except that the weak current generated by the radio waves has to be amplified to do its job of carrying a signal round a radio. Dr Novack, by contrast, proposes to create a current strong enough to be tapped as a source of power.
He and his colleagues designed their infra-red antennae using data they collected while studying how metals behave when exposed to infra-red rays. They tweaked the composition, shape and size of the antennae until they arrived at spiral structures a few nanometres (billionths of a metre) across. The key to commercialising this idea is that such antennae can be stamped by the billion on to plastic sheets. The stamps themselves are made by etching silicon wafers using the technique that makes microprocessors, and the sheets can be shaped to coat anything from cars to portable electronic devices.
The remaining hurdle, admittedly a high one, is to collect the current from the antennae. The usual way to do this would be to use a rectifier-a device that converts alternating to direct current. However, the current in the nanoantennae oscillates at a rate of trillions of cycles a second, which is beyond the range of existing rectifiers. What is needed are smaller rectifiers which would, by very dint of their size, rectify current of an appropriatefrequency.
If that could be done, a new type of solar cell would be available. And not just solar. All hot objects give off infra-red. If you put such a cell next to, say, an engine's exhaust pipe, you would have the ultimate form of recycling.
一种新型太阳能电池呼之欲出
红外线在能源的各种替代来源中并不是那么引人瞩目。太阳能电池更倾向靠可见光，甚至是紫外线来发电。可是，在光频谱中存在大量的红外线，所以，忽略它似乎就有些不明智了。美国爱达荷州国家实验室的史蒂文.纳瓦克（Steven Novack）也就因此一直在寻找各种方法利用红外线来发电-从本月上旬在美国机械工程师学会于佛罗里达杰克逊维尔召开的会议上他透露的情况看，他似乎已经找到了一种方法。
太阳能电池能发电，是因为可见光和紫外线有足够的能量使电子挣脱原子的束缚。这些电子移动就形成了可供使用的直流电。红外线却不具备足够的能量引发这一过程。不过，它的能量足以引发电子产生振动-特别是那些金属晶格内的自由漂浮电子。设计一个结构使电子以类似音叉的方式发生共振，这样你就等于有了一种发电机，因为发生共振的电子从效果看就是一种交流电。事实上，这就是无线天线的工作方式，唯一的区别是这里不需要对无线电波产生的微弱电流要进行放大处理，来让无线电波携带要传输的信号。通过对比，纳瓦克（Novack）博士打算利用这一原理来生产足以用作供电来源的较强电流。
他和同事曾对各种金属在红外线照射下表现出的特性进行了研究，他们利用研究时收集的数据设计了红外线天线组。他们改进天线组的结构、形状和大小，直到最后采用了一些几纳米（十亿分之一米）宽的螺旋结构。这一设计商业化的关键是这种天线组要能够以数以万计的数量贴到塑料片上。这些贴片自身是由蚀刻硅片制成，而硅片用到了制造微处理器时所使用的技术，可以做成各种形状覆盖到从小汽车到便携电子设备的任何产品上。剩下的障碍客观地讲也比较困难，那就是从这些天线组收集电流。完成这步常用的方法是使用整流器-一种把交流电转换成直流电的器件。不过，纳米天线中的电流以每秒上亿个周期的速率振荡，这超出了现有整流器的工作范围。我们需要的是比较小的整流器，正是凭藉它们较小的尺寸，来对相应频率的电流进行整流。
如果这步得以实现，我们就会得到一种新型太阳能电池。所有发热物体都发射出红外线。如果你把这样的电池靠近比如说引擎排气管类的（发热）物体，就实现了废物利用的终极形式。
关键字:双语新闻
生词表:
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