Gaigalas A K, Wang Lili, Choquette Steven
National Institute of Standards and Technology, Gaithersburg, MD 20899.
J Res Natl Inst Stand Technol. 2013 Jan 10;118:1-14. doi: 10.6028/jres.118.001. eCollection 2013.
A commercial spectrometer with a 150 mm integrating sphere (IS) detector was used to estimate the scattering and absorption cross sections of monodisperse polystyrene microspheres suspended in water. Absorbance measurements were performed with the sample placed inside the IS detector. The styrene absorption was non zero for wavelengths less than 300 nm. Correction for fluorescence emission by styrene was carried out and the imaginary part of the index of refraction, ni, was obtained. Absorbance measurements with the sample placed outside the IS detector were sensitive to the loss of photons from the incident beam due to scattering. The absorbance data was fitted with Lorenz-Mie scattering cross section and a correction for the finite acceptance aperture of the spectrometer. The fit parameters were the diameter, the suspension concentration, and the real part of the index of refraction. The real part of the index was parameterized using an expansion in terms of powers of the inverse wavelength. The fits were excellent from 300 nm to 800 nm. By including the imaginary part obtained from the absorbance measurements below 300 nm, it was possible to obtain a good fit to the observed absorbance data over the region 240 nm to 800 nm. The value of ni at 266 nm was about 0.0060±0.0016 for microspheres with diameters of 1.5 μm, 2.0 μm, and 3.0 μm. The scattering cross section, absorption cross section, and the quantum yield at 266 nm of microsphere with a diameter of 2.0 μm was 5.65±0.01 μm(2), 1.54±0.03 μm(2), and 0.027±0.002 respectively. The styrene absorption reduces the scattering cross section by 20 % at 266 nm.
使用一台配备150毫米积分球（IS）探测器的商用光谱仪来估算悬浮在水中的单分散聚苯乙烯微球的散射和吸收截面。将样品置于IS探测器内部进行吸光度测量。对于波长小于300纳米的情况，苯乙烯的吸收不为零。对苯乙烯的荧光发射进行了校正，并获得了折射率的虚部(n_i)。将样品置于IS探测器外部进行吸光度测量时，由于散射，对入射光束中光子的损失很敏感。吸光度数据采用洛伦兹 - 米氏散射截面进行拟合，并对光谱仪有限的接收孔径进行校正。拟合参数为直径、悬浮浓度和折射率的实部。折射率的实部通过逆波长幂次展开进行参数化。在300纳米至800纳米范围内拟合效果极佳。通过纳入从300纳米以下吸光度测量获得的虚部，可以在240纳米至800纳米区域内对观测到的吸光度数据进行良好拟合。对于直径为1.5微米、2.0微米和3.0微米的微球，在266纳米处(n_i)的值约为0.0060±0.0016。直径为2.0微米的微球在266纳米处的散射截面、吸收截面和量子产率分别为5.65±0.01微米²、1.54±0.03微米²和0.027±0.002。在266纳米处，苯乙烯的吸收使散射截面降低了20%。
