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jiangcj09

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[交流] Dynamic Light Scattering(DLS)测定纳米颗粒大小的仪器原理 已有2人参与

DLS是基于布朗运动(Brownian motion),通过测定颗粒的扩散系数(diffusion coefficient,D)而根据Stokes-Einstein公式计算颗粒的大小。
Malvern zetasizer的手册讲:“It does this by illuminating the particles with a laser and analysing the intensity fluctuations in the scattered light.”
但是,另一本书里描述的DLS原理跟Malvern zetasizer手册上说的不一致:“The precisely defined frequencies associated with laser sources make it possible to exploit light scattering to study the motion of colloidal particles. Light scattered by a moving particle will experience a Doppler shift to slightly higher or lower frequency depending on whether the particle is moving towards or away from the observer. For a collection of particles moving at random by virtue of their Brownian motion, a Doppler frequency broadening will result. Mixing this broadened, scattered signal with incident light produces a pattern of beat frequencies, the measurement of which allows the diffusion coefficient of the particles to be calculated.
......
The width of the Doppler broadened peak at half-height is related to the diffusion coefficient…”
(Duncan J. Shaw (1992), Introduction to Colloid and Surface Chemistry, 4th Edition, page: 61-62)

是不是可以这样理解:第二种说法理论上也对,但是现在的zetasizer都是通过测散射光的强度变化来求扩散系数和颗粒大小,而不是通过测定Doppler展宽来实现?
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jiangcj09

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2楼2013-04-06 00:44:32
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douhaosuda

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厉害,赞一个
新手初来咋到,大侠们多多指教哈
3楼2013-04-06 09:10:41
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4楼2013-04-06 10:01:08
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