无论是在沙滩上、星空下还是在冬日的家中，没有什么能比围坐在一堆火焰旁昏昏欲睡更惬意的了。然而，科学家研究火，可不是出于一般的好奇，从化学构成角度帮助我们了解火的奥秘。 

    美国科学家在火中发现了新的化合物。美国科技中心视频新闻2005年12月16日在该网站通过视频介绍了科学家的新发现。 科学中心新闻（ScienCentral News）视频报道解释说，该发现揭开了有关火的部分谜团，并可能为人类带来新的清洁燃料。

    来自加州Livermore的Sandia国家实验室的燃烧化学家说：“火的化学构成之所以重要，是因为它可以帮助我们设计并发明一些设备，以便减少燃烧所造成的污染。” 
 尽管科学家对火的研究已有150多年的历史，但这次是科学家首先在乙烯（一种用来制造普通塑料聚乙烯的物质）燃烧的火焰中发现烯醇（enols）这种化合物。
    克雷格·塔提耶（Taatjes，他是在加州一个国家实验室专门研究燃烧的化学家）解释说：“在以前的火焰中，我们从来没有发现过这种分子，而且它们在燃烧模型中也不存在，因此我们很吃惊。由于长久以来，人类就了解到其他相关化合物——酮类（keto）存在于火中，而这种化合物的质量与烯醇相同，因此人们长久以来忽略了烯醇的存在。” 
    他还解释说，研究燃烧这一化学反应对设计出新的设备，以减少污染物排放有重要作用。
    他还说：“我们非常了解燃烧，然而在一些细微之处也的确存在空白。燃烧是极为复杂的过程，在一团小小的火焰中也有几百种物质，它们相互发生着数以千计的化学反应。”

烯醇可能与污染存在联系！

塔提耶和来自不同国家的科学家组成研究小组，他们将燃烧过程中的上千种化学反应分类，发现大多数火焰中都含有烯醇，从技术上可以将它归入醇类化合物。塔提耶认为这类化合物可能和污染存在联系。 
　　“它们是汽车排放的尾气形成过程中的重要介质，”塔提耶解释说，“几乎所有的燃烧过程从一开始就含有碳，结束时形成最终物质二氧化碳和水。木头燃烧是这样的，煤、原油、汽油燃烧也是这样的。同时还有一些微量的化合物，生成其他的污染物。” 
　　据《探索》杂志报道，塔提耶用一种特殊设计、叫做同步加速器的高能辐射探测器分析了不同燃料总共14种火焰类型，分析出火中不同的化学反应过程。 
　　使用这个设备不仅能识别出火焰中的分子包含什么原子，还能够看清这些原子是怎样结合在一起的。这样，人们就可以辨别出包含相同的原子的不同分子。 
　　首先，一个防火的石英圆锥体将燃烧产生的气体抽入与之相连的真空容器内。然后，用一束强辐射线照射，气体中的一些成分因此带电，随即被探头发现，塔提耶就是这样发现了烯醇。 
　　烯醇的发现，帮助人们改进引擎污染现状 
　　他说：“我们从火焰的任一部分提取出分子，经过质量分光计分析，实质就是根据分子的质量判定是什么分子。”但是当分子质量相当时，就像烯醇和酮类化合物，科学家就得用射线照射分子，看看这些分子携带电子的紧密程度。同步加速器中的一个金属盘将分子打向一个带电极的探头。塔提耶根据带电分子到达电极所用的时间判断出是什么分子。 
　　这一新的认识或许能帮助人们设计新的引擎，减少污染物的排放，让天空更蓝，更清澈。 

　　塔提耶最后说，烯醇还存在于星际空间，更多地了解烯醇也能帮助科学家认识星际空间的物质存在形式。 

    研究结果曾刊登在2005年6月24日的《科学》杂志上，研究得到美国能源部的资金支持。

附：刊登在《科学》杂志上的原文

Scientists have discovered compounds never before found in flame. As this ScienCentral News video explains, the finding cracks some of the mystery of fire and could lead to cleaner-burning fuel. 

Hidden in the Flames 

Whether it's on the beach under a star-filled sky or at home during winter, for some, there's nothing nicer than sitting beside a fire and becoming mesmerized by the flames. But, some scientists are staring into fires, for reasons beyond their own curiosity, and shedding light on the chemical mysteries of flame. 

"That's important in trying to design devices that emit less pollution and so that's where the details of the chemistry matter," explains combustion chemist Craig Taatjes from Sandia National Laboratories in Livermore, California. 

Although scientists have been studying the chemistry of fire for more than 150 years, this is the first time they found compounds, called enols, in a flame that was produced by ethylene, the substance used to make the common plastic polyethylene. "These molecules had not been seen in flames and they're not in models of flames. So we were surprised," explains Taatjes. Until now enols were obscured from detection by other related compounds, known as keto, that shares the same mass and have long been known to exist in fire. 

"We understand how things burn, very well, and it's really in the details that there are some gaps in our understanding," he says. "Combustion's a very complicated process. There are thousands of reactions of hundreds of species even in a very simple flame." 

 
Quartz cone 
 
Sorting through thousands of these chemical reactions in flames, Taatjes and a team of international scientists discovered that most fires contain enols, which technically fall into the family of alcohols. Taatjes thinks they might be involved in pollution. 

"They're important intermediates in the chemistry that determine what will come out of the tailpipe," he explains. "Almost everything that we burn starts out with something that has carbon in it and we end up with carbon dioxide and water. That's true for wood flames, that's true for coal or that's true for oil or gasoline flames. And there are then also some trace compounds that may be in these other fuels, which will generate other kinds of pollutants." 

As reported in Discover magazine, Taatjes analyzed 14 flame types fed by different fuel sources using a specially-designed, high-energy radiation probe, called a synchrotron, that picks apart a fire's chemistry. 

"This apparatus can tell not only what atoms are in the molecules that we're looking at in flame, but how those atoms are put together," he says. "So we can tell the difference between two kinds of molecules, which are made of the same atoms but just put together differently." 

First, a fire-proof quartz cone attached to a vacuum sucks the flame's exhaust into a chamber. There, a powerful light beam zaps the exhaust and electrifies certain components, drawing them into a detector that helped Taatjes identify enols. 

"So we can suck out molecules at any part of the flame and see what chemicals are there," Taatjes explains. The molecules are normally then analyzed using a mass spectrometer. "Essentially we decide what molecules they are by how heavy they are," he says, but when molecules, like enols and keto, weigh the same, they have to zap the molecules with light to see how tightly they hold onto their electrons. A metal plate in the synchrotron then "kicks" them to a detector using electrical pulses. Taatjes tracks the amount of time it takes the electrified molecules to reach the detector. The travel time tells them what they are dealing with, in this case the enols. 

This missing piece of the puzzle might help scientists design new engines that emit fewer pollutants, paving the way for clearer skies. 

Taatjes says enols can also be found in interstellar space, so learning more about them could tell scientists more about how matter formed there. 

Taatjes' work was published in the journal Science on June 24, 2005, and was funded by the U.S. Department of Energy.