Showing 5 results for Gold Nanoparticles
Mina Eslamifar, Nastaran Mansour,
Volume 6, Issue 1 (10-2012)
Abstract
In this work, thermo-optical properties of gold nanoparticle colloids are studied using continuous wave (CW) laser irradiation at 532 nm. The nanoparticle colloids are fabricated by 18 ns pulsed laser ablation of pure gold plate in the distilled water. The formation of the nanoparticles has been evidenced by optical absorption spectra and transmission electron microscopy. The nonlinear optical properties of gold nanoparticles colloids are investigated by closed Z-scan under irradiation of a low power CW laser. It will be shown that the thermal lens model is in excellent agreement with the experimental results of samples. The aperture-limitted optical limiters based on the nonlinear refraction of colloidal solution are presented. The tunability of limiting threshold of optical limiters can be accomplished by engineering of the experimental geometry.
Dr. Faegheh Hajizadeh, Dr. S.nader S. Reihani,
Volume 7, Issue 1 (6-2013)
Abstract
Thanks to their unique optical and electromagnetic properties, noble-metal nanoparticles are proven very useful in many scientific fields, from nanotechnology to biology, including detection of cancer cells. Irradiated gold nanoparticles, as a nano-smolder could be widely used in biomedical contexts such as tumor therapy. Laser destruction of a cancerous tissue depends on thermal and physical properties of the tissue, therefore temperature quantification of an irradiated metallic nanoparticle in different materials could be followed by interesting applications. In this research we quantify the temperature of irradiated gold nanoparticles in paraffin which is the most commonly used material for embedding of biological tissues in pathology. We have shown that the temperature increase rate for irradiated gold nanoparticles with diameters of 78 nm, 97 nm, and 149 nm are 1.31, 1.40, and 2.28 ◦C/mW, respectively. Considering that the conductivity of a biological tissue is an important parameter on temperature raise and destruction, these results could yield a valuable insight into the cancer therapy.
Foozieh Sohrabi, Seyedeh Mehri Hamidi,
Volume 13, Issue 2 (12-2019)
Abstract
Compared to the long history of plasmonic gratings, there are only a few studies regarding the bandgap in the propagation of plasmonic surface waves. Considering the previous studies on interpretation of plasmonic bandgap formation, we discuss this phenomenon using the effect of both surface plasmon polariton (SPP) and localized surface plasmon (LSP) for our fabricated one-dimensional metallic-polymeric grating. This structure is composed of metallic grating on the surface of PDMS with different concentration of embedded gold nanoparticles. By sweeping the incident angles, we have seen that the SPP, LSP and their coupling cause two gaps in reflection regime which are originated from SPP supported by thin film gold film and LSP supported by gold nanoparticles. The first gap is attributed to the patterned metallic film because it vanishes by increasing the nanoparticles which may destroy the pattern while the second gap can be formed by embedded nanoparticles because it becomes more considerable by raising the incubation time. Therefore, the drowning time of patterned samples (e.g. 24h, 48h, and 72h) in HAuCl4 plays the key role in adjustability of plasmonic bandgap. Notably, the interaction between SPP and LSP can be the origin of the shift in gap center from 300 to 550. To best of over knowledge, this study is the first study on the plasmonic band gap as a function of both SPP and LSP.
Parisa Khajegi, Majid Rashidi-Huyeh,
Volume 15, Issue 1 (1-2021)
Abstract
Nobel metal nanoparticles (NPs) are widely used in various applications including optical and biological sensors, biomedicine, photocatalysts, electronics, and photovoltaic cells. The optical properties of gold NPs are surveyed in this paper under the Localized Surface Plasmon Resonance (LSPR) effect, which increases the light absorption and scattering at the LSPR wavelength. This LSPR frequency depends on various factors, including the shape and size of the particles as well as incident electromagnetic polarization. Here, the optical response of gold NPs with different shapes and sizes are investigated using the finite element method (FEM). The results show that the bandwidth, amplitude, and LSPR wavelength depend on the shape and dimensions of the NPs as well as the polarization of the incident light. The LSPR wavelength changes from 500 to 650 nm for different shapes of the gold NPs including sphere, octahedral, cube, ellipsoid, triangle, and with identical volume. To study the NP size effect on the optical properties, the absorption and scattering cross-sections (CSs) are also investigated for different sizes of NPs. The results show a redshift in the LSPR wavelength by increasing the NP size.
Hanie Yazdanfar , Seyedeh Mehri Hamidi, Neda Roostaei, Younes Mazhdi, Asieh Soheilian,
Volume 16, Issue 1 (1-2022)
Abstract
ta charset="UTF-8" >Color vision deficiency (CVD) is a disorder in which patients cannot distinguish specific colors. In the last few decades, the researchers have attempted to find a solution to cure this deficiency, despite valuable attempts by scientists, a promising and effective remedy has not been attained yet. As curing of CVD with the tinted or dyed glasses and lenses in colorblind patients is not satisfying, in this work, we have studied a novel and simple method using plasmonic gold nanoparticles in the contact lenses to improve CVD based on surface plasmon resonance of gold nanoparticles in the visible spectral range. In this technique, the dispersion of gold particles into the contact lens and transforming them to plasmonic gold nanoparticles provides a color filter that can be applied in the correction of the red-green type of colorblindness.The modified lens blocks a narrow band centered at 560nm, the wavelength that vision spectra of CVD patients overlap at those ones.
