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hu59828141

木虫 (小有名气)

应助: 1 (幼儿园)
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帖子: 88
在线: 22小时
虫号: 908617
注册: 2009-11-21
专业: 生物物理、生物化学与分子

[求助] DLS动态光散射仪Mean Diameter比Effective Diameter小，请问为什么？

各位木虫龘龘，我是刚接触DLS动态光散射仪，不是很懂，通过水合粒径分析，给出我几个值，分别是：Effective Diameter、Lognormal Size Distribution Results、Multimodal Size Distribution Results，但是我的effective diameter是19.9纳米的时候，其他的两个results中的值都要小于effective diameter，比如Multimodal Size Distribution Results中的Mean Diameter只有11.246，请问哪个值才是准确的？为什么Mean Diameter要小于Effective Diameter？请帮我解释一下，谢谢各位龘龘
以下是DLS给出的数据：
**** Brookhaven Instruments Corp.****
ZetaPlus Particle Sizing Software Version 4.11
Sample Identification:64-1min (Combined)
Operator Identification: hhl
Notes: 2016-04-29
Measurement Date: Apr 29, 2016
Measurement Time: 22:52:06
Batch: 0

**** Measurement Parameters ****
Temperature = 20.0
Suspension = Water
Viscosity = 1.002 cp
Ref.Index Fluid = 1.331
Angle = 90.00
Wavelength = 659.0 nm
Dust Cutoff = 20.00
Runs Completed = 5
Run Duration = 00:00:10
Total Elapsed Time = 00:00:50
Average Count Rate = 439.1 kcps
Ref.Index Real = 1.000
Ref.Index Imag = 4.400

**** Measurement Results ****
64-1min (Combined)
Effective Diameter: 19.9
Polydispersity: 0.233
Baseline Index: 8.2/100.00%
Elapsed Time = 00:00:50

Run Eff. Diam. (nm) Half Width (nm) Polydispersity Baseline Index
---------------------------------------------------------------------------
  1       18.3             6.6             0.129       9.1/100.00%
  2       18.8             8.8             0.218       7.6/100.00%
  3       20.3             9.9             0.237       9.1/100.00%
  4       21.4          10.7             0.250       5.8/100.00%
  5       22.2          11.7             0.279       7.0/100.00%
---------------------------------------------------------------------------
Mean       20.2             9.5             0.223       7.7/100.00%
Std.Error    0.7             0.9             0.025       0.6/  0.00
Combined    19.9             9.6             0.233       8.2/100.00%

**** Lognormal Size Distribution Results ****
GSD: 1.580
d(nm)  G(d) C(d) | d(nm)  G(d) C(d) | d(nm)  G(d) C(d)
--------------------------------------------------------------
   3.3 26 5  |    6.1 97 40  |    9.2 80 75
   3.9 44 10  |    6.5 99 45  |    9.9 70 80
   4.4 58 15  |    6.9  100 50  | 10.8 58 85
   4.7 70 20  |    7.3 99 55  | 12.1 44 90
   5.1 80 25  |    7.7 97 60  | 14.2 26 95
   5.5 87 30  |    8.1 93 65  |
   5.8 93 35  |    8.6 87 70  |

**** Multimodal Size Distribution Results ****
Mean Diameter: 11.246
Relative Variance: 0.008
Skew: 13.569

d(nm)  G(d) C(d) | d(nm)  G(d) C(d) | d(nm)  G(d) C(d)
--------------------------------------------------------------
   8.5 0 0  | 16.3 0  100  | 31.3 0  100
   9.0 0 0  | 17.3 0  100  | 33.2 0  100
   9.6 0 0  | 18.4 0  100  | 35.2 0  100
10.2 51 16  | 19.5 0  100  | 37.4 0  100
10.8 95 46  | 20.7 0  100  | 39.7 0  100
11.4  100 78  | 21.9 0  100  | 42.1 0  100
12.1 54 95  | 23.3 0  100  | 44.6 0  100
12.9 16  100  | 24.7 0  100  | 47.4 0  100
13.7 0  100  | 26.2 0  100  | 50.2 0  100
14.5 0  100  | 27.8 0  100  | 53.3 0  100
15.4 0  100  | 29.5 0  100  | 56.6 0  100

**** Lognormal Size Distribution Results/Spreadsheet Format  ****
3.3, 26,  5
3.9, 44, 10
4.4, 58, 15
4.7, 70, 20
5.1, 80, 25
5.5, 87, 30
5.8, 93, 35
6.1, 97, 40
6.5, 99, 45
6.9,100, 50
7.3, 99, 55
7.7, 97, 60
8.1, 93, 65
8.6, 87, 70
9.2, 80, 75
9.9, 70, 80
  10.8, 58, 85
  12.1, 44, 90
  14.2, 26, 95

**** Multimodal Size Distribution Results/Spreadsheet Format ****
8.5,  0,  0
9.0,  0,  0
9.6,  0,  0
  10.2, 51, 16
  10.8, 95, 46
  11.4,100, 78
  12.1, 54, 95
  12.9, 16,100
  13.7,  0,100
  14.5,  0,100
  15.4,  0,100
  16.3,  0,100
  17.3,  0,100
  18.4,  0,100
  19.5,  0,100
  20.7,  0,100
  21.9,  0,100
  23.3,  0,100
  24.7,  0,100
  26.2,  0,100
  27.8,  0,100
  29.5,  0,100
  31.3,  0,100
  33.2,  0,100
  35.2,  0,100
  37.4,  0,100
  39.7,  0,100
  42.1,  0,100
  44.6,  0,100
  47.4,  0,100
  50.2,  0,100
  53.3,  0,100
  56.6,  0,100

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