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Analysis of SiO<sub>2</sub> particle size using photon correlation spectroscopy
Kim, Hyunki,Lee, Jaeran,Kim, Sok Won Elsevier 2018 OPTIK -STUTTGART- Vol.157 No.-
<P><B>Abstract</B></P> <P>In this study, fixed SiO<SUB>2</SUB> particle sizes were observed using a photon correlation spectroscopy (PCS) system. PCS measurements were carried out using samples of fixed SiO<SUB>2</SUB> particles uniformly dispersed on the surface of a cover glass and particles moving in a liquid. The monodispersed spherical SiO<SUB>2</SUB> particles were made using the Stöber process with tetraethyl orthosilicate (TEOS) concentrations of 0.1M, 0.2M, and 0.3M. The solid sample was made by fixing the particles on a cover glass by self-assembly, and the liquid sample was made by dispersing particles in distilled water. The fixed particle sizes on the surface were measured by PCS as 263.1±21.7nm, 309.3±28.2nm, and 425.4±14.6nm for TEOS concentrations of 0.1M, 0.2M, 0.3M respectively. The corresponding liquid colloidal particle sizes were measured as 252.5±8.0nm, 322.8±23.1nm, and 423.2±12.2nm. The PCS show agreement with SEM images within ±9%.</P>
Yesul Han,이유미,김석원,Jaeran Lee 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.51
FCS (fluorescence correlation spectroscopy) is a technique used to determine the dynamic characteristics of particles in solution and was made common in the field of biophysics with the development of confocal microscopy, the high-speed photo-detector, and real-time data acquisition systems. In this study, the FCS system was composed of a commercial fluorescence microscope, a He-Ne laser (632.8 nm), a data acquisition board, and a software correlator written with LabVIEW. Autocorrelation functions were obtained using the measured fluorescence fluctuations of fluorescent beads and Q-dots (quantum dots) coated with carboxylate in distilled water. The diffusion coefficients of the beads and Q-dots in distilled water and PBS (phosphate buffered saline) solution were obtained using the viscosity of water and bead size. Also using the bead size, the viscosity of the PBS solution was calculated, and the Q-dots in water and PBS solution were compared. The result showed that the viscosity of the PBS solution was 2.5 times greater than that of water, and the sizes of Q-dots in water and PBS solution were one-third and one-sixth smaller than the known values, respectively, due to the pH variation in the solutions.
형광입자들의 크기와 농도에 따른 형광 상관 분광함수 측정
한예슬,이재란,김석원,Han, Yesul,Lee, Jaeran,Kim, Sok Won 한국광학회 2012 한국광학회지 Vol.23 No.3
형광입자의 크기와 수에 따라 형광 신호의 상관함수 변화를 측정하는 형광상관분광법을 이용하여 용액 내에서 확산 운동하는 나노크기 형광 입자들의 농도와 유체역학적 반지름을 비교하였다. 시료에 사용된 나노크기 형광 입자들은 Alexa Fluor 647, 양자점, 형광 bead이고, 증류수에서 1/10, 1/100로 입자들이 들어있는 용액을 희석하여 각 입자들에 대해 3가지의 다른 농도의 시료를 준비하였다. Alex Fluor 647의 알려져 있는 확산시간을 이용하여 형광상관분광장치의 유효초점 부피를 구하고, 각 입자들의 확산계수, 크기, 희석에 따른 농도 변화를 측정할 수 있었다. 본 연구를 통해, 자체 제작된 형광상관분광장치로 임의적으로 희석된 시료들의 농도를 약 0.1 nM ~ 10 nM의 범위에서 측정할 수 있었고, 양자점의 확산계수를 $27{\pm}1{\mu}m^2/s$로 결정할 수 있었다. The concentration and hydrodynamic radius of nano-sized fluorescence particles diffusing in solution were compared by using fluorescence correlation spectroscopy (FCS), which can measure the variation of the correlation function of a fluorescence signal by size and number of particles. The used nano-sized fluorescence particles are Alex Fluor 647, quantum dots, and fluorescence beads, and three kinds of sample solutions with different concentrations were prepared by dilution to 1/10 and 1/100 with distilled water for each kind of particles. The effective focal volumes were calculated by using the known diffusion coefficient of Alexa Fluor 647 particles, and the diffusion time, number of particles in focal volume, and variation of concentration according to the dilution could be measured by the FCS system. Through this study, we determined that the concentrations of arbitrarily diluted sample solutions can be measured by a home-built FCS setup in the range of 0.1 nM ~ 10 nM and that the diffusion coefficient of the quantum dot was $27{\pm}1{\mu}m^2/s$.
형광상관분광법을 이용한 광세기에 따른 유효 초점 부피 변화에 대한 연구
정찬배,이재란,김석원,Jeong, Chanbae,Lee, Jaeran,Kim, Sok Won 한국광학회 2013 한국광학회지 Vol.24 No.2
Using fluorescence correlation spectroscopy, we analyzed the change of effective focal volume of a confocal system with light intensity. The fluorescence correlation spectroscopy system was home-built in accordance with the He-Ne laser with a wavelength of 632.8 nm, and two kinds of samples (AlexaFluor657 and Quantum dot655) suitable for the wavelength of the laser beam were used. For each sample, we analyzed and compared the correlation functions obtained while changing the intensity of the light source in a range of 1~50 ${\mu}W$. The result shows that the radius of the focal area increases linearly through the increase of particle number and diffusion time in response to an intensity change in weak light below 10 ${\mu}W$. In the higher intensity region (>10~15 ${\mu}W$), the increasing rate of particle number and diffusion time keep increasing but at a much slower rate. Through this result, it was also found that the radius increasing rate of the focal area was reduced however, the radius still increased slightly. 형광상관분광법을 이용하여 광세기에 따른 공초점 시스템의 유효 초점 부피의 변화를 분석하였다. 형광상관분광장치는 632.8 nm 파장의 He-Ne 레이저에 맞춰서 실험실에서 자체 제작하였고, 시료 또한 레이저 파장에 적합한 두 종류의 시료 AlexaFluor647과 quantum dot 655를 사용하였다. 각 시료에 대해 광원의 세기를 1~50 ${\mu}W$ 범위내에서 변화시켜가며 얻어진 상관함수를 비교 분석하였다. 10 ${\mu}W$ 이하의 약한 광 세기에서는 세기 변화에 따라 입자수와 확산시간이 증가하는 것을 통해 초점 영역의 반지름이 선형적으로 증가하는 결과를 보였다. 반면 10~15 ${\mu}W$ 이상에서는 입자의 수와 확산 시간의 증가율은 감소하였지만 미세하게 계속해서 증가하는 결과를 보였고, 이 결과를 통해 초점영역의 반지름 역시 증가율은 감소하였지만 미세하게 증가한 것을 알 수 있었다.