Zeta電位儀測試簡化過程

1、Zeta電位儀測試簡化過程1、 開啟儀器(儀器的開關(guān)在設(shè)備的后面的右上部位)，0>Turning on the instrument<0>將出現(xiàn)“嘟嘟”聲，指示儀器已開啟，開始初始化步驟；如果儀器完成例程，出現(xiàn)第二次“嘟嘟”聲。<00>Two further beeps will be heard to indicate the instrument has reached the “default” temperature of 25°C.<0>將再次聽到兩次“嘟嘟”聲，說明儀器已達(dá)到25°C的默認(rèn)溫度。因?yàn)楸緝x器為632.8激光

2、光源，一般需穩(wěn)定30分鐘2、 點(diǎn)擊圖標(biāo)，啟動(dòng)Zetasizer軟件3、 點(diǎn)擊軟件中 File New - Measurement file，創(chuàng)建此次測試文件，一經(jīng)創(chuàng)建，本次測試的結(jié)果均自動(dòng)保存在此文件中，無需另行保存。4、 制備樣品5、 將江 制備的樣品注入樣品池，粒徑分布需1.0 ml1.5 ml，Zeta點(diǎn)位測量至少需要1.0 ml。6、 0><0>將樣品池插入儀器中，等待溫度平衡<07、 0><0>點(diǎn)擊Start （），<0<0>即進(jìn)行測量。8、 使用光盤拷取數(shù)據(jù)。使用注意事項(xiàng)測量粒徑分布1. 測量粒徑前，需查知樣品分散劑的粘度

3、、折光指數(shù)（Refractive Index）2. 用卷紙輕輕點(diǎn)拭樣品池外側(cè)水滴，切勿用力擦拭，以防將樣品池劃傷，如發(fā)現(xiàn)樣品池有劃紋，需更換。3. 手盡量避免觸摸樣品池下端，否則會(huì)影響光路。4. 一定要去除樣品池內(nèi)的氣泡5. 實(shí)驗(yàn)室提供的樣品池為聚苯乙烯材質(zhì)，不可用于測量有機(jī)分散體系6. 實(shí)驗(yàn)室提供的樣品池,測量溫度不可高于50攝氏度7. 如需測量有機(jī)分散體系或高于50攝氏度，請自帶石英比色皿8. 使用濾紙過濾時(shí)，舍去過濾后的第一滴樣品，以防濾紙上雜質(zhì)進(jìn)入樣品池測量時(shí)需自帶：卷紙、多個(gè)注射器、多個(gè)離心管（用于稀釋樣品）Zeta電位測量1、 測量粒徑前，需查知樣品分散劑的粘度、折光指數(shù)（Refr

4、active Index）、介電常數(shù)（Dielectric constant）2、 用卷紙輕輕點(diǎn)拭樣品池外側(cè)水滴，尤其是兩個(gè)塞子外側(cè)3、 一定要去除樣品池內(nèi)的氣泡，尤其是電極上氣泡4、 如發(fā)現(xiàn)電極變黑，需更換5、 實(shí)驗(yàn)室提供的樣品池為聚苯乙烯材質(zhì)，不可用于測量有機(jī)分散體系6、 實(shí)驗(yàn)室提供的樣品池測量溫度不可高于70度7、 使用濾紙過濾時(shí)，舍去過濾后的第一滴樣品，以防濾紙上雜質(zhì)進(jìn)入樣品池測量時(shí)需自帶：卷紙、多個(gè)注射器（5ml）、多個(gè)離心管（用于稀釋樣品）使用使用光盤 0> <75>制備樣品 粒徑<00>Sample concentration<0>樣品濃

5、度<00>Each type of sample material has its own ideal range of sample concentration for optimal measurements.<0>每個(gè)類型的樣品材料，有最佳的樣品濃度測量范圍。<0n 0>If the sample concentration is too low, there may not be enough light scattered to make a measurement.<0>如果樣品濃度太低，可能會(huì)沒有足夠的散射光進(jìn)行測量。<0 0

6、>This is unlikely to occur with the Zetasizer except in extreme circumstances.<0>除極端情況外，對該儀器來說一般不會(huì)發(fā)生。<0n 0>If the sample is too concentrated, then light scattered by one particle will itself be scattered by another (this is known as multiple scattering).<0>如果樣品太濃，那么一個(gè)粒子散射光也會(huì)被其它粒

7、離所散射（這稱為多重散射）。<0n 0>The upper limit of the concentration is also governed by the point at which the concentration no longer allows the sample to freely diffuse, due to particle interactions.<0>濃度的上限也要考慮到：在某一濃度以上，由于粒子間相互作用，粒子不再進(jìn)行自由擴(kuò)散。<0<00>Particle size<0>粒徑<00>Min. C

8、oncentration (Recommended)<0>最小濃度（推薦）<00>Max. Concentration (Recommended)<84>最大濃度（推薦）<00>< 10nm<0>< 10nm<00>0.5g/l<0>0.5g/l<00>Only limited by the sample material interaction, aggregation, gelation etc.<0>僅由樣品材料相互作用、聚集、膠凝作用等限制<00>10nm

9、 to 100nm<0>10nm to 100nm<00>0.1mg/l<100>0.1mg/l<00>5% mass (assuming a density of 1g/cm3)<0>5%質(zhì)量（假定密度1g/cm3）<00>100nm to 1µm<0>100nm to 1µm<00>0.01g/l<100>0.01g/l（10-3%質(zhì)量）<01%質(zhì)量（假定密度1g/cm3）<00>> 1µm<0>> 1µ

10、;m<00>0.1g/l<100>0.1g/l（10-2%質(zhì)量）<00>(10-2 % mass) 1% mass (assuming a density of 1g/cm3)<99>1%質(zhì)量（假定密度1g/cm3）<00>Considerations for small particles<0>小粒子需要考慮的事項(xiàng)<00>Minimum concentration<0>最小濃度<00>For particle sizes smaller than 10nm, the major fac

11、tor in determining a minimum concentration is the amount of scattered light that the sample generates.<0>對小于10nm的粒子，決定最小濃度的主要因素是樣品生成的散射光強(qiáng)。<0 0>In practice, the concentration should generate a minimum count rate of 10,000 counts per second (10kcps) in excess of the scattering from the dis

12、persant.<0>實(shí)用的角度，這種濃度應(yīng)生成最低光強(qiáng)為10，000cp/s（10 kcps），這樣才能超過分散劑的散射。<0 0>As a guide, the scattering from water should give a count rate in excess of 10kcps, and toluene in excess of 100kcps.<0>作為一個(gè)指導(dǎo)，水的散射光強(qiáng)應(yīng)超過10kcp的，甲苯的應(yīng)超過100kcps。<00>Maximum concentration<0>最大濃度<00>For

13、samples with small particle sizes, a maximum concentration does not really exist (in terms of performing Dynamic Light Scattering (DLS) measurements).<0>對小粒徑的樣品，最大濃度實(shí)際上不存在（以進(jìn)行動(dòng)態(tài)光散射（DLS）測量的術(shù)語來說）。<00>However, in practice, the properties of the sample itself will set the maximum value.<0

14、>但實(shí)際，樣品的性質(zhì)本身會(huì)決定此最大值。<0 0>For example, the sample may have the following properties:<0>例如，樣品可能有以下性質(zhì)：<0n 0>Gelation.<0>膠凝作用：<0 0>A gel is unsuitable for measurement using the Zetasizer (this is true for all instruments based on Dynamic Light Scattering).<0>凝膠不適合采

15、用Zetasizer進(jìn)行測量（這對所有基于動(dòng)態(tài)光散射原理儀器都是事實(shí)）<0n 0>Particle interactions.<0>粒子相互作用：<0 0>If there are interactions between the particles then the diffusion constant of the particles usually changes, leading to incorrect results.<0>如果粒子之間存在相互作用，那么粒子的擴(kuò)散常數(shù)通常會(huì)改變，導(dǎo)致不正確的結(jié)果。<0 0>A concen

16、tration should be chosen to avoid particle interactions.<0>應(yīng)選擇某一濃度避免粒子相互作用。<00>Considerations for large particles<75>大顆粒需要考慮的事項(xiàng)<00>Minimum concentration<100>最小濃度<00>Even for larger particles, the minimum concentration is effectively still a function of the amount

17、of scattered light, though the additional effect of “number-fluctuation” must be taken into account.<0>即使對大顆粒，知道最小濃度仍然是得到有效散射光強(qiáng)的保障，雖然我們還必須考慮“Number fluctuation”（數(shù)量 波動(dòng): 粒子濃度太低導(dǎo)致在光路中的粒子數(shù)量隨時(shí)間較大波動(dòng)）的附加效應(yīng)。<00>As an example, if a sample of large particles (say 500nm) were to be measured at low

18、concentration (say 0.001 g/l (10-4%), the amount of scattered light generated would be more than sufficient to perform a measurement.<0>例如，如果在低濃度（比如說0.001 g/l （10-4%）下測量一個(gè)大顆粒（比如說500nm）樣品，生成的散射光大于進(jìn)行測量的所需量。<0 0>However, the number of particles in the scattering volume is so small (fewer th

19、an 10) that severe fluctuations of the momentary number of particles in the scattering volume will occur.<0>但是，散射體積中粒子數(shù)太?。ㄐ∮?0），在散射體積中會(huì)發(fā)生嚴(yán)重的粒子數(shù)量隨時(shí)間波動(dòng)。<0 0>These fluctuations are not the type assumed by the calculation method used, or will generally be misinterpreted as larger particles w

20、ithin the sample.<0>這些波動(dòng)與所用計(jì)算方法中假設(shè)的類型不符，通常會(huì)被錯(cuò)誤詮釋為樣品中的大顆粒。<00>Such fluctuations must be avoided and this determines the lower limit for the required concentration and for a lower limit in the number of particles.<0>必須避免此類波動(dòng)，這決定了所要求濃度的下限和粒子數(shù)的下限。<0 光路中0>At least 500 particles sh

21、ould be present, however, a minimum of 1000 particles is recommended.<0>至少應(yīng)存在500個(gè)粒子，但推薦最小量為1000個(gè)粒子。<0 0>See the figure below for an estimate plot of the number of particles per scattering volume for different concentrations assuming a density of 1 g/cm³.<0>參見下圖：對假定密度為1 g/cm

22、79;的不同濃度溶液中，每散射體積中粒子數(shù)的估算圖。<00>Maximum concentration<100>最大濃度<00>The upper limit for the sample concentration for larger particles is determined by their tendency to cause multiple-scattering.<0>較大顆粒的樣品濃度上限，由其引起多重散射的趨勢決定。<0 雖然0>Although the Zetasizer is not very sensitiv

23、e to multiple-scattering, with increased concentration, the effect of the multiple-scattering becomes more and more dominant, up to a point where so much multiple-scattering is generated that the results of the measurement will be affected.<0>Zetasizer對多重散射不是十分敏感，但隨著濃度增加，多重散射效應(yīng)越來越占優(yōu)勢，在達(dá)到某一濃度時(shí)，

24、生成過多的多重散射，會(huì)影響測量結(jié)果。<0 0>Of course, such a high concentration should not be used for accurate measurements, and rough estimates are given for maximum concentrations for the different size classes in the table above.<0>當(dāng)然，如此高的濃度不應(yīng)用于精確測量，上表中給出了不同粒徑粒子最大濃度的粗略估算。<00>As a general rule, mea

25、sure at the highest concentration possible before multiple scattering and particle interactions affect the result.<0>通用規(guī)則是，在多重散射和粒子相互作用影響結(jié)果之前，以可能的最高濃度進(jìn)行測量 。<0 0>Dust contamination in the sample can be presumed equal for high and low concentrations, and thus, the amount of scattered light

26、 from the sample increases in relation to the scattering from the dust contamination as the concentration increases.<0>可以假定樣品中的灰塵污染對高濃度和低濃度是相同的，因此樣品濃度增加，從樣品得到的散射光強(qiáng)相對灰塵散射光強(qiáng)有所增加。<00>Filtration<0>過濾<00>All liquids used to dilute the sample (dispersants and solvents) should be fi

27、ltered before use to avoid contaminating the sample.<0>用于稀釋樣品（分散劑和溶劑）的所有液體，應(yīng)于使用前過濾，避免污染樣品。<0 0>The size of the filter will be determined by the estimated size of the sample.<0>過濾器的粒徑應(yīng)由樣品的估算粒徑?jīng)Q定。<0 0>If the sample is 10nm, then 50nm dust will be an important contaminant in the

28、 dispersant.<0>如果樣品是10nm，那么50nm灰塵將是分散劑中的重要污染物。<0 0>Aqueous dispersants can be filtered down to 0.2µm, while non-polar dispersants can be filtered down to 10 or 20nm.<0>水相分散劑可被0.2µm孔徑膜過濾，而非極性分散劑可被10或20nm孔徑膜過濾。<00>Samples are not filtered if at all possible.<0>盡

29、可能不過濾樣品。<0 0>Filters can remove sample by absorption as well as physical filtration.<0>過濾膜能通過吸附以及物理過濾消耗樣品。<0 0>Only filter the sample if aware of larger sized particles, such as agglomerates, that need to be removed as they are not of interest, or cause result variations.<0>只

30、有在溶液中有較大粒徑粒子如聚集物時(shí)，且它們不是所關(guān)心的成分，或可能引起結(jié)果改變，才過濾樣品。<00>Using ultrasonics<0>運(yùn)用超聲波<00>Ultrasonication can be used to remove air bubbles or to breakup agglomerates - however, this must be applied carefully in order to avoid damaging the primary particles in the sample.<0>可使用超聲處理除去氣泡或

31、破壞聚集物 但是，必須謹(jǐn)慎應(yīng)用，以便避免損壞樣品中的原有粒子。<0 0>Limits for the use of ultrasonication in terms of intensity and application time are strongly sample dependent.<0>使用超聲的強(qiáng)度和施加時(shí)間方面，依賴于樣品。<0 0>Minerals such as titanium dioxide are ideal candidates for dispersion by high powered probes, however, the

32、 particle size of some materials, such as carbon black, may depend on the power and length of time ultrasonication is applied.<0>礦物質(zhì)如二氧化鈦，是通過超聲探頭進(jìn)行分散的一個(gè)理想的例子，但是某些礦物質(zhì)，如炭黑，的粒徑，可能依賴于所應(yīng)用的功率和超聲處理時(shí)間。<0超聲甚至可使得0>Some materials can even be forced to aggregate using ultrasound.<0>某些礦物質(zhì)粒子聚集。&

33、lt;00>Emulsions and liposomes should not be ultrasonicated.<0>乳狀液和脂質(zhì)體不得采用超聲處理。0> <0>制備樣品 Zeta電位<00>The optical arrangement for zeta potential measurements in the Zetasizer Nano series means that the concentration requirements are not as strict as those used for size and molec

34、ular weight measurements.<0>Zetasizer Nano中用于Zeta電位測量的光學(xué)設(shè)置在第15章中討論。使用一束激光作為光源，激光被一個(gè)分光鏡分為一束入射光和一束參考光。參考光的光強(qiáng)在出廠時(shí)設(shè)置，通常在2000至3500Kcps之間。入射光穿過樣品池的中央，散射光在向前的角度被檢測。因此總的來說對于Zeta電位測量的樣品應(yīng)該光學(xué)透明。最高和最低樣品濃度可依賴于以下因素：n 粒子的光學(xué)性質(zhì)n 粒子粒徑n 粒子的分散度在Zeta電位測量過程中，首先測量參考光的強(qiáng)度，并且顯示在Log sheet中。隨后檢測散射光強(qiáng)度，并由衰減器調(diào)節(jié)散射光的強(qiáng)度至參考光源的1

35、/10。舉個(gè)例子說，如果參考光源的光強(qiáng)是2600kcps, 衰減器將會(huì)調(diào)節(jié)散射光強(qiáng)不高于260kcps.如第5章所述，儀器中的衰減器有11個(gè)位置，覆蓋從100%至0.0003%透射率在Zeta電位測試過程中的最小光強(qiáng)為20kcps，低于此光強(qiáng)測試將中止。Zeta電位測試中的最低濃度在Zeta電位測試過程中所需的最小光強(qiáng)為20kcps。因此最低濃度取決于相對折光指數(shù)差（粒子和溶劑間的折光指數(shù)差值）和粒子尺寸。粒子的尺寸越大所產(chǎn)生的散射光越強(qiáng)，所需的濃度也就越低。舉例來說，氧化鈦粒子的水性懸浮液。氧化鈦的折光指數(shù)為2.5，與水的折光指數(shù)差較大，因此有較強(qiáng)的散射能力。因此對于300nm的氧化鈦粒子，

36、最小濃度可以為10-6 w/v %。對于折光指數(shù)差很小的樣品，比如蛋白質(zhì)溶液，最低濃度會(huì)高很多。通常最低濃度需要在0.11w/v %之間才能有足夠的散射光強(qiáng)進(jìn)行Zeta電位測量。最終，對于特定樣品進(jìn)行一個(gè)成功的Zeta電位測量的最低濃度，應(yīng)該由試驗(yàn)實(shí)際測量得到。Zeta電位測試中的最高濃度對于在本儀器的Zeta電位測量的最高濃度沒有一個(gè)明確的答案。以上討論的因素，如粒子的粒徑，分散度，樣品的光學(xué)性質(zhì)，都應(yīng)考慮。Zeta電位測量過程中的散射光在向前的角度收集，因此激光應(yīng)該能夠穿過樣品。如果樣品的濃度過高，則激光將會(huì)由于樣品的散射衰減很多，相應(yīng)的降低檢測到的散射光光強(qiáng)。為了補(bǔ)償此影響，衰減器會(huì)讓更

37、過的激光通過。最終，樣品的濃度范圍必須由測定不同濃度下的Zeta電位的試驗(yàn)決定，由此來得到濃度對Zeta電位的影響。0>Many samples will require dilution and this procedure is absolutely critical in determining the final value measured.<0>多數(shù)樣品要求稀釋，這個(gè)步驟在確定最終測量值中是至關(guān)重要的。<0 0>For meaningful measurements the dilution medium is crucially important.

38、<0>對有意義的測量，稀釋介質(zhì)也是非常重要的。<0 0>A measurement result given with no reference to the medium in which the material is dispersed is meaningless.<0>所給出的測量結(jié)果，如沒有提及所分散的介質(zhì)，則是沒有意義的。<0 0>The zeta potential is as dependent on the composition of the disperse phase as it is on the nature of

39、the particle surface.<0>Zeta電位依賴于分散相的組成，因?yàn)樗鼪Q定了粒子表面的特性。<00>Dilution Medium<0>稀釋介質(zhì)<00>The continuous phase of most samples can arbitrarily be put into one of two categories:<0>大多數(shù)樣品的分散相，可以歸于兩類之一：<0n 0>Polar dispersants are defined as those with a dielectric constant

40、 greater than 20 e.g. ethanol and water.<0>介電常數(shù)大于20的分散劑被定義為極性分散劑，如乙醇和水。<0n 0>Non-polar or low polarity dispersants are defined as those with a dielectric constant less than 20, e.g. hydrocarbons, higher alcohols.<0>介電常數(shù)小于20的分散劑被定義為非極性或低極性分散劑，如碳?xì)浠衔镱悺⒏呒?jí)醇類。<00>Aqueous/Polar Sys

41、tems<0>水相/極性系統(tǒng)<00>The aim of sample preparation is to preserve the existing state of the surface during the process of dilution.<0>制備樣品的目標(biāo)，是在稀釋過程中，保留表面的現(xiàn)存狀態(tài)。<0 0>There is only one way to ensure this is the case.<0>只有一種方式保證這種情況。<00>This is by filtering or centrifug

42、ing some clear liquid form the original sample and using this to dilute the original concentrated sample.<0>即通過過濾或離心原始樣品，得到清澈的分散劑，使用這種分散劑稀釋原有濃度樣品。<0 0>In this way the equilibrium between surface and liquid is perfectly maintained.<0>以這種方式，完美地維持了表面與液體之間的平衡。<00>If extraction of

43、 a supernatant is not possible, then just letting a sample naturally sediment and using the fine particles left in the supernatant is a good method.<0>如果提取上清液是不可能的，那么需讓樣品自然沉淀，使用上清液中留下的小粒子是比較好好的方法。<00>Zeta potential is not a size-dependent parameter using the approximation of the Smolucho

44、wski theory.<0>使用Smoluchowski理論近似，Zeta電位不是粒徑依賴性參數(shù)。<00>Another method is to imitate the original medium as closely as possible.<0>另一種方法是盡可能接近地模擬原始介質(zhì)。<0 需0>This should be done with regard to:<0>考慮下述條件：<0n 0>pH.<0>pH。<0n 0>Total ionic concentration of the

45、 system.<0>系統(tǒng)的總離子濃度。<0n 0>Concentration of any surfactants or polymers present.<0>存在的任何表面活性劑或聚合物的濃度<00>Non-Polar Systems<0>非極性系統(tǒng)<00>Measuring samples in insulating media such as hexane, isoparaffin, etc. is far from easy.<0>在絕緣介質(zhì)如正己烷、異鏈烷烴中，測量樣品是極為不易。<0 0&

46、gt;It requires the use of the universal dip cell.<0>它要求使用universal dip cell（通用插入式樣品池）。<0 0>This is required because of its chemical compatibility and the close spacing of the electrodes which allows the generation of high field strengths without using excessively high voltages.<0>因

47、為此樣品池較好的化學(xué)兼容性以及電極間的狹窄空間，這對于不使用高電壓時(shí)，生成較高磁場強(qiáng)度是必需的。<00>Sample preparation for such systems will follow the same general rules as for polar systems.<0>這種系統(tǒng)的樣品制備，將遵照與極性系統(tǒng)相同樣的規(guī)則。<0 0>As there will be generally fewer ions in a non polar dispersant to suppress the zeta potential, the actua

48、l values measured can seem very high, as much as 200 or 250mV.<0>由于在非極性分散劑中，通常很少有離子以抑制Zeta電位，所測量的實(shí)際值似乎是非常高的，如200或250 mV。<0 0>In such non-polar systems, equilibration of the sample after dilution is the time dependent step, equilibration can take in excess of 24 hours.<0>在這樣的非極性系統(tǒng)中，

49、稀釋后樣品的平衡呈時(shí)間依賴性，平衡時(shí)間可超過24小時(shí)。0>Folded capillary cell<0>彎曲式毛細(xì)管樣品池<00>Fill the cell as described below<0>如下所述填充樣品池：<0n 0>Prepare the sample in a syringe of at least 1ml capacity.<0>用注射器取至少1ml樣品。<0n 0>Place the sample syringe into one of the sample ports.<0>將注

50、射器與樣品池一端連接。<0n 0>Slowly inject the sample through the cell_, checking that all air bubbles are removed.<0>將樣品緩慢注射入樣品池，檢查是否除去所有氣泡。<00>If a bubble forms under the sample port, pull the syringe plunger back to draw the bubble into the syringe body and then reinject.<0>如果在樣品池端口下形

51、成一個(gè)氣泡，將注射器活塞拉回，使氣泡吸回注射器體，再重新注 射。<0n 0>Once sample starts to emerge from the second sample port, insert a stopper_.<0>一旦樣品開始從第二個(gè)樣品端口冒出，插入塞子。<0n 0>Remove the syringe and replace with a second stopper_.<0>移去注射器，插入第二個(gè)塞子。<0n 0>No bubbles should be seen within the clear capil

52、lary area of the cell.<0>在樣品池的透明毛細(xì)區(qū)域，不應(yīng)看到任何氣泡。<0 0>If necessary tap the cell lightly to dislodge them.<0>必要時(shí)，輕拍樣品池以驅(qū)逐氣泡。<0 0>Check that the cell electrodes are still completely covered.<0>檢查樣品池電極是否仍然完全被樣品淹沒。<0n 0>Remove any liquid that may have spilt onto the elec

53、trodes.<0>移去濺在外部電極上的任何液體。<0注意：進(jìn)行測量之前，必須配置塞子。粒徑測量原理什么是動(dòng)態(tài)光散射？ <00>The Zetasizer Nano series performs size measurements using a process called Dynamic Light Scattering (DLS)<0>Zetasizer Nano系列使用稱為動(dòng)態(tài)光散射（DLS）的過程進(jìn)行粒徑測量。<00>Dynamic Light Scattering (also known as PCS - Photon Cor

54、relation Spectroscopy) measures Brownian motion and relates this to the size of the particles.<0>動(dòng)態(tài)光散射（也稱為PCS 光子相關(guān)光譜）測量布朗運(yùn)動(dòng)，并將此運(yùn)動(dòng)與粒徑相關(guān)。<0 0>It does this by illuminating the particles with a laser and analysing the intensity fluctuations in the scattered light.<0>這是通過用激光照射粒子，分析散射光的光

55、強(qiáng)波動(dòng)實(shí)現(xiàn)的。<00>Scattering intensity fluctuations<0>散射光波動(dòng)<00>If a small particle is illuminated by a light source such as a laser, the particle will scatter the light in all directions.<0>如果小粒子被光源如激光照射，粒子將在各個(gè)方向散射。<00>If a screen is held close to the particle, the screen will

56、 be illuminated by the scattered light.<0>如果將屏幕靠近粒子，屏幕即被散射光照亮。<0 0>Now consider replacing the single particle with thousands of stationary particles.<0>現(xiàn)在考慮以千萬個(gè)粒子代替單個(gè)粒子。<0 0>The screen would now show a speckle pattern as shown below.<0>屏幕將出現(xiàn)如下所示的散射光斑。<00>The speck

57、le pattern will consist of areas of bright light and dark areas where no light is detected.<0>散射光斑由明亮和黑暗的區(qū)域組成，在黑暗區(qū)域不能監(jiān)測到光。<00>What causes these bright and dark areas?<0>什么引起這些明亮區(qū)域和黑暗區(qū)域？<00>The diagram below shows the propagated waves from the light scattered by the particles.

58、<0>下圖顯示粒子散射光的傳播的波動(dòng)。<00>The bright areas of light are where the light scattered by the particles arrive at the screen with the same phase and interferes constructively to form a bright patch.<0>光的明亮區(qū)域是：粒子散射光以同一相位到達(dá)屏幕，相互疊加相干形成亮斑。<0 0>The dark areas are where the phase additions

59、 are mutually destructive and cancel each other out.<0>黑暗區(qū)域是：不同相位達(dá)到屏幕互相消減。<00>In the above example we said that the particles are not moving.<0>在上例中，我們說粒子是不運(yùn)動(dòng)的。<0 0>In this situation the speckle pattern will also be stationary - in terms of both speckle position and speckle s

60、ize.<0>在這種情況下，散射光斑也將是靜止的 即散射光斑位置和散射光斑大小都是不變的。<00>In practice, particles suspended in a liquid are never stationary.<0>實(shí)際上，懸浮于液體中的粒子從來不是靜止的。<0 0>The particles are constantly moving due to Brownian motion.<0>由于布朗運(yùn)動(dòng)，粒子不停地運(yùn)動(dòng)。<0 0>Brownian motion is the movement of par

61、ticles due to the random collision with the molecules of the liquid that surrounds the particle.<0>布朗運(yùn)動(dòng)是由于與環(huán)繞粒子的分子隨機(jī)碰撞引起的粒子運(yùn)動(dòng)。<0 0>An important feature of Brownian motion for DLS is that small particles move quickly and large particles move more slowly.<0>對DLS來說，布朗運(yùn)動(dòng)的一個(gè)重要特點(diǎn)是：小粒子運(yùn)動(dòng)快

62、速，大顆粒運(yùn)動(dòng)緩慢。<0 0>The relationship between the size of a particle and its speed due to Brownian motion is defined in the Stokes-Einstein equation.<0>在Stokes - Einstein方程中，定義了粒徑與其布朗運(yùn)動(dòng)所致速度之間的關(guān)系。<00>As the particles are constantly in motion the speckle pattern will also appear to move.<0>由于粒子在不停地運(yùn)動(dòng)，散射光斑也將出現(xiàn)移動(dòng)。<0 0>As the particles move around, the constructive and destructive phase addition of the s