激光光散射测量荧光/磷光体系溶液结构的原理和方法
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摘要
通过对商业化激光光散射谱仪改造升级,以4种不同波长的激光785、632.8、532和457 nm作为独立光源,可以根据不同的荧光体系选择不同的入射激光,有效避免荧光、磷光对散射光信号的干扰,从而使激光光散射谱仪能用于荧光/磷光等吸光材料溶液结构的测定.非荧光和荧光聚苯乙烯小球标准样品的测定都验证了改造后仪器测量结果的准确性和精确性.实验结果表明,当荧光体系对入射光有吸收时,动态光散射的相关函数与静态光散射得到的均方回转半径都不能反映荧光样品的真实溶液结构,此时的结果只能作为定性参考,只有选择样品无吸收的入射光波长,符合(准)弹性散射时,所测结果才能反映样品的真实结构.单分子荧光谱仪的对照实验证实了改造光散射谱仪的正确性与必要性.
As a typical elastic scattering technique,laser light scattering results cannot precisely describe the solution structure when the samples absorb incident light. Therefore,commercial laser light scattering instrument has been modified and upgraded to utilize four independent lasers,e. g. 785 nm,632. 8 nm,532 nm and 457 nm,respectively as the light sources. By switching the wavelengths of incident lasers to avoid the sample absorption,the instrument can be widely used in fluorescent / phosphorescence solution systems.Spherical polystyrene nanoparticles with and without fluorescent dyes are used to calibrate the modified instrument. It is found that the height of the normalized intensity-intensity time correlation function decreases with the increase of the scattering angle when the sample absorbs the incident laser light. Such a correlation function fails to describe the sample solution structure,because the corresponding hydrodynamic radius distribution shows two modes and the average characteristic line width < Г > versus the square of scattering vector q2 does not fit a good linear relationship any more. Therefore,another laser which is not absorbed by the sample is used to do the calibration again. The corresponding intensity-intensity time correlation functions and the fitting results can precisely describe the solution structure. Fluorescence correlation spectroscopy( FCS) is also conducted to further prove the results obtained from the modified laser light scattering instrument are precise and accurate.
As a typical elastic scattering technique,laser light scattering results cannot precisely describe the solution structure when the samples absorb incident light. Therefore,commercial laser light scattering instrument has been modified and upgraded to utilize four independent lasers,e. g. 785 nm,632. 8 nm,532 nm and 457 nm,respectively as the light sources. By switching the wavelengths of incident lasers to avoid the sample absorption,the instrument can be widely used in fluorescent / phosphorescence solution systems.Spherical polystyrene nanoparticles with and without fluorescent dyes are used to calibrate the modified instrument. It is found that the height of the normalized intensity-intensity time correlation function decreases with the increase of the scattering angle when the sample absorbs the incident laser light. Such a correlation function fails to describe the sample solution structure,because the corresponding hydrodynamic radius distribution shows two modes and the average characteristic line width < Г > versus the square of scattering vector q2 does not fit a good linear relationship any more. Therefore,another laser which is not absorbed by the sample is used to do the calibration again. The corresponding intensity-intensity time correlation functions and the fitting results can precisely describe the solution structure. Fluorescence correlation spectroscopy( FCS) is also conducted to further prove the results obtained from the modified laser light scattering instrument are precise and accurate.
引文
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2 Wu C,Zhou S Q.Phys Rev Lett,1996,77(14):3053~3055
3 Cheng H,Shen L,Wu C.Macromolecules,2006,39(6):2325~2329
4 Liu M Z,Cheng R S,Wu C.Eur Polym J,1999,35(10):1907~1910
5 Wu C,Zhou S Q.Macromolecules,1997,30(3):574~576
6 Gao Jun(高均),Wu Chi(吴奇).Acta Polymerica Sinica(高分子学报),1997,(3):324~330
7 Zuo Ju(左榘),Niu Aizhen(牛爱珍),An Yingli(安英丽),He Binglin(何炳林),Ran Shaofeng(冉少峰),Liang Dehai(梁德海).Acta Polymerica Sinica(高分子学报),1998,(4):419~423
8 Xu Jiankuan(徐建宽),He Zhimin(何志敏),Zuo Ju(左榘),Acta Polymerica Sinica(高分子学报),2002,(1):58~62
9 Zhou C L,Zhao Y,Jao T C,Wu C,Winnik M A.J Phys Chem B,2002,106(37):9514~9521
10 Cheng H,Wu C,Winnik M A.Macromolecules,2004,37(13):5127~5129
11 Wu C,Zhou S Q.Macromolecules,1996,29(5):1574~1578
12 Dai Z J,Ngai T,Wu C.Soft Matter,2011,7(9):4111~4121
13 Jin F,Wu C.Phys Rev Lett,2006,96(23):237801
14 Wu C,Li LW.Polymer,2013,54(5):1463~1465
15 Li J F,Li W,Huo H,Luo S Z,Wu C.Macromolecules,2008,41(3):901~911
16 Li J F,Ngai T,Wu C.Polym J,2010,42(8):609~625
17 Zhao Y,Liang H J,Wang S G,Wu C.J Phys Chem B,2001,105(4):848~851
18 Zhang G Z,Winnik F M,Wu C.Phys Rev Lett,2003,90(3):035506
19 Yan J J,Ji W X,Chen E Q,Li Z C,Liang D H.Macromolecules,2008,41(13):4908~4913
20 Chu B.Laser Light Scattering:Basic Principles and Practice.Boston:Academic Press,1991.34~61
21 Han C C,Akcasu A Z.Plane Waves,Scattering,and Polymers,in Scattering and Dynamics of Polymers.Singapore:John Wiley&Sons(Asia)Pte Ltd,2011.1~26
22 Huang Y,Cheng H,Han C C.Macromolecules,2010,43(23):10031~10037
23 Huang Y,Cheng H,Han C C.Macromolecules,2011,44(12):5020~5026
24 Wei G M,Yao D D,Li Z Y,Hu Y,Cheng H,Han C C.Macromolecules,2013,46(3):1212~1220
25 Han C C,Akcasu A Z.Fluctuations,Correlation,and Static/Dynamic Scattering,in Scattering and Dynamics of Polymers.Singapore:John Wiley&Sons(Asia)Pte Ltd,2011.27~102