Sizing gold nanoparticles by optical extinction spectroscopy

Abstract

In s t it u t e of Ph y s ic s P u bl is h in g AbstractT h e m e a s u re m e n t o f o p tic a l e x tin c tio n is u se d to d e te rm in e th e siz e o f n e a rly sp h e ric a l g o ld n a n o p a rtic le s su s p e n d e d in so lu tio n , p ro d u c e d by a re v e rse m ic e lle s p ro c e s s. T h e c o n tra st b e tw e e n th e m a x im u m a n d th e m in im u m in th e e x tin c tio n sp e c tra a ro u n d 4 5 0 a n d 5 2 0 n m sh o w s a lin e a r d e p e n d e n c e w ith th e m e a n ra d iu s o f th e g o ld p a rtic le s le ss th a n 3 n m ; how ever, th e m e th o d c a n b e u se d to siz e p a rtic le s u p to 7 n m . E x p e rim e n ta l re s u lts for ex tin c tio n sp e c tra c a n b e fitte d b y M ie s th e o ry i f th e o p tic a l co n sta n ts fro m b u lk m a te ria l v alu es a re m o d ifie d b y in tro d u c in g th e lim ita tio n o f th e m e a n fre e p a th d u e to c o llisio n s o f c o n d u c tio n e le c tro n s w ith th e b o u n d a ry o f th e n a n o p a rtic le s.

Fine structure of gold nanoparticles stabilized by buthyldithiol: Species identified by Mössbauer spectroscopy

“…4A) Taking into account the shape of the curve as well as the size of the synthesized nanoparticles the registered spectrum is in good agreement with the experimental results published previously [25,26]. The characteristic plasmonic band appears at around 500 nm, indicating a decrease in particle size [39]. The intensity of this band is small, the smallest particles probably do not contribute to the signal since plasmon excitation does not develop on them [7].…”

Evaluation of Optical Properties of Ag, Cu, and Co Nanoparticles Synthesized in Organic Medium

“…For metals where there is a substantial bound electron component, like cobalt, the dielectric function can be decomposed into two terms: free-electron term and interband term [12]. Consequently, dielectric function becomes additive from two components: free-electron term and bound-electron term [12]:…”

“…Consequently, dielectric function becomes additive from two components: free-electron term and bound-electron term [12]:…”

Determination of size and refractive index of single gold nanoparticles using an optofluidic chip

“…12 For real-time measurement, direct imaging using CCD is essentially impossible due to the diffraction limit. [13][14][15][16] For refractive index measurement, emissivity measurement technique, 17 spectroscopic ellipsometry, 18 reflection and transmission measurements 19 and optical spectrum 20 are not feasible for real-time measurement. And they are incapable to measure the refractive index of single gold nanoparticles.…”

“…In addition, real-time optical spectrum is difficult to be applied to the single nanoparticle level. 20 As a result, it remains a great challenge to determine the diameter and refractive index of single gold nanoparticles in real-time, which imposes barrier in practical applications.…”