文章来源:未知 文章作者:meng 发布时间:2010-09-02 02:23 字体: [ ]  进入论坛

Physicists2 at the National Institute of Standards and Technology (NIST) have used a small crystal of ions(离子) (electrically charged atoms) to detect forces at the scale of yoctonewtons. Measurements of slight forces—one yoctonewton is equivalent to(等于,相当于) the weight of a single copper3 atom on Earth—can be useful in force microscopy(显微镜检查) , nanoscale science, and tests of fundamental physics theories. A newton is already a small unit: roughly the force of Earth's gravity on a small apple. A yoctonewton is one septillionth(第10的) of a newton (yocto means 23 zeros after the decimal place小数位, or 0.000000000000000000000001).

Measurements of vanishingly(难以觉察地) small forces typically are made with tiny mechanical oscillators(振荡器) , which vibrate like guitar strings4. The new NIST sensor5, described in Nature Nanotechnology, is even more exotic(异国的,外来的) —a flat crystal of about 60 beryllium ions trapped inside a vacuum chamber6 by electromagnetic fields(电磁场) and cooled to 500 millionths of a degree above absolute zero with an ultraviolet laser. The apparatus7(装置,设备) was developed over the past 15 years for experiments related to ion plasmas(等离子体) and quantum computing8. In this case, it was used to measure yoctonewton-scale forces from an applied9 electric field. In particular, the experiment showed that it was possible to measure about 390 yoctonewtons in just one second of measurement time, a rapid speed that indicates the technique's high sensitivity. Sensitivity is an asset(资产,优点) for practical applications.

The previous force measurement record with this level of sensitivity was achieved by another NIST physicist1 who measured forces 1,000 times larger, or 500 zeptonewtons (0.0000000000000000005 newtons) in one second of measurement time using a mechanical oscillator. Previous NIST research indicated that a single trapped ion could sense forces at yoctonewton scales but did not make calibrated10 measurements.

The ion sensor described in Nature Nanotechnology works by examining how an applied force affects ion motion, based on changes in laser light reflected off the ions. A small oscillating electric field applied to the crystal causes the ions to rock back and forth11; as the ions rock, the intensity12 of the reflected laser light wobbles(摇晃,摇摆) in sync with the ion motion. A change in the amount of reflected laser light due to the force is detectable13, providing a measure of the ions' induced motion using a principle similar to the one at work in a police officer's radar14 gun. The technique is highly sensitive because of the low mass of the ions, strong response of charged particles to external electric fields, and ability to detect nanometer-scale changes in ion motion.


1 physicist oNqx4     
  • He is a physicist of the first rank.他是一流的物理学家。
  • The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。
2 physicists 18316b43c980524885c1a898ed1528b1     
物理学家( physicist的名词复数 )
  • For many particle physicists, however, it was a year of frustration. 对于许多粒子物理学家来说,这是受挫折的一年。 来自英汉非文学 - 科技
  • Physicists seek rules or patterns to provide a framework. 物理学家寻求用法则或图式来构成一个框架。
3 copper HZXyU     
  • The students are asked to prove the purity of copper.要求学生们检验铜的纯度。
  • Copper is a good medium for the conduction of heat and electricity.铜是热和电的良导体。
4 strings nh0zBe     
  • He sat on the bed,idly plucking the strings of his guitar.他坐在床上,随意地拨着吉他的弦。
  • She swept her fingers over the strings of the harp.她用手指划过竖琴的琴弦。
5 sensor sz7we     
  • The temperature sensor is enclosed in a protective well.温度传感器密封在保护套管中。
  • He plugged the sensor into a outlet.他把传感器插进电源插座。
6 chamber wnky9     
  • For many,the dentist's surgery remains a torture chamber.对许多人来说,牙医的治疗室一直是间受刑室。
  • The chamber was ablaze with light.会议厅里灯火辉煌。
7 apparatus ivTzx     
  • The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
  • They had a very refined apparatus.他们有一套非常精良的设备。
8 computing tvBzxs     
  • to work in computing 从事信息处理
  • Back in the dark ages of computing, in about 1980, they started a software company. 早在计算机尚未普及的时代(约1980年),他们就创办了软件公司。
9 applied Tz2zXA     
  • She plans to take a course in applied linguistics.她打算学习应用语言学课程。
  • This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。
10 calibrated 6ac8922cd7bfd487c7dd1bd65d0f6191     
v.校准( calibrate的过去式和过去分词 );使标准化;使合标准;测量(枪的)口径
  • Power pesticide dusters can be calibrated and used to apply pertilizer. 动力杀虫剂可以调整用来施肥。 来自辞典例句
  • The flexible diaphragm is connected to a plat cantilever-calibrated spring. 柔韧的膜片一扁平的悬臂校正弹簧相连。 来自辞典例句
11 forth Hzdz2     
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
12 intensity 45Ixd     
  • I didn't realize the intensity of people's feelings on this issue.我没有意识到这一问题能引起群情激奋。
  • The strike is growing in intensity.罢工日益加剧。
13 detectable tuXzmd     
  • The noise is barely detectable by the human ear.人的耳朵几乎是察觉不到这种噪音的。
  • The inflection point at this PH is barely detectable.在此PH值下,拐点不易发现。
14 radar kTUxx     
  • They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
  • Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。
TAG标签: weight crystal yoctonewton