R. Liang, M. Hatat-Fraile, H. He, M. Arlos, M. Servos, Y. Norman Zhou
Organic contaminants and corrosion in water treatment effluents are a current global problem and the development of effective methods to facilitate the removal of organic contaminants and corrosion control strategies are required to mitigate this problem. TiO2 nanomaterials that are exposed to UV light can generate electron-hole pairs, which undergo redox reactions to produce hydroxyl radicals from adsorbed molecular oxygen. They hydroxyl radicals are able to oxidize organic contaminants in water. This same process can be used in conjunction to protect metals from corrosion via cathodic polarization. In this work, TiO2 nanomaterials were synthesized and electrophoretically deposited on conductive substrates to serve as films or membranes. An illuminated TiO2 film on a conductive surface served as the photoanode and assisted in the cathodic protection of stainless steel (SS304) and the degradation of organic pollutants, in this case glucose. This proof-of-concept relied on photoelectrochemical experiments conducted using a potentiostat and a xenon lamp illumination source. The open-circuit potential changes that determine whether a metal is protected from corrosion under illumination was observed; and the electrical characteristics of the TiO2 film or membrane under dark and arc lamp illumination conditions were also analyzed. Furthermore, the effect of organic contaminants on the photocathodic protection mechanism and the oxidation of glucose during this process were explored.
{"title":"TiO2 membranes for concurrent photocatalytic organic degradation and corrosion protection","authors":"R. Liang, M. Hatat-Fraile, H. He, M. Arlos, M. Servos, Y. Norman Zhou","doi":"10.1117/12.2188466","DOIUrl":"https://doi.org/10.1117/12.2188466","url":null,"abstract":"Organic contaminants and corrosion in water treatment effluents are a current global problem and the development of effective methods to facilitate the removal of organic contaminants and corrosion control strategies are required to mitigate this problem. TiO2 nanomaterials that are exposed to UV light can generate electron-hole pairs, which undergo redox reactions to produce hydroxyl radicals from adsorbed molecular oxygen. They hydroxyl radicals are able to oxidize organic contaminants in water. This same process can be used in conjunction to protect metals from corrosion via cathodic polarization. In this work, TiO2 nanomaterials were synthesized and electrophoretically deposited on conductive substrates to serve as films or membranes. An illuminated TiO2 film on a conductive surface served as the photoanode and assisted in the cathodic protection of stainless steel (SS304) and the degradation of organic pollutants, in this case glucose. This proof-of-concept relied on photoelectrochemical experiments conducted using a potentiostat and a xenon lamp illumination source. The open-circuit potential changes that determine whether a metal is protected from corrosion under illumination was observed; and the electrical characteristics of the TiO2 film or membrane under dark and arc lamp illumination conditions were also analyzed. Furthermore, the effect of organic contaminants on the photocathodic protection mechanism and the oxidation of glucose during this process were explored.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122146661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electromagnetic radiation propagating through any molecular system typically experiences a characteristic change in its polarization state as a result of light-matter interaction. Circularly polarized light is commonly absorbed or scattered to an extent that is sensitive to the incident circularity, when it traverses a medium whose constituents are chiral. This research assesses specific modifications to the properties of circularly polarized light that arise on passage through a system of surface-functionalized spherical nanoparticles, through the influence of chiral molecules on their surfaces. Non-functionalized nanospheres of atomic constitution are usually inherently achiral, but can exhibit local chirality associated with such surface-bound chromophores. The principal result of this investigation is the quantification of functionally conferred nanoparticle chirality, manifest through optical measurements such as circularly polarized emission. The relative position of chiral chromophores fixed to a nanoparticle sphere are first determined by means of spherical coverage co-ordinate analysis. The total electromagnetic field received by a spatially fixed, remote detector is then determined. It is shown that bound chromophores will accommodate both electric and magnetic dipole transition moments, whose scalar product represents the physical and mathematical origin of chiral properties identified in the detected signal. The analysis concludes with discussion of the magnitude of circular differential optical effects, and their potential significance for the characterization of surface-functionalized nanoparticles.
{"title":"Surface functionalized spherical nanoparticles: an optical assessment of local chirality","authors":"J. M. Leeder, Henryk T. Haniewicz, D. Andrews","doi":"10.1117/12.2186514","DOIUrl":"https://doi.org/10.1117/12.2186514","url":null,"abstract":"Electromagnetic radiation propagating through any molecular system typically experiences a characteristic change in its polarization state as a result of light-matter interaction. Circularly polarized light is commonly absorbed or scattered to an extent that is sensitive to the incident circularity, when it traverses a medium whose constituents are chiral. This research assesses specific modifications to the properties of circularly polarized light that arise on passage through a system of surface-functionalized spherical nanoparticles, through the influence of chiral molecules on their surfaces. Non-functionalized nanospheres of atomic constitution are usually inherently achiral, but can exhibit local chirality associated with such surface-bound chromophores. The principal result of this investigation is the quantification of functionally conferred nanoparticle chirality, manifest through optical measurements such as circularly polarized emission. The relative position of chiral chromophores fixed to a nanoparticle sphere are first determined by means of spherical coverage co-ordinate analysis. The total electromagnetic field received by a spatially fixed, remote detector is then determined. It is shown that bound chromophores will accommodate both electric and magnetic dipole transition moments, whose scalar product represents the physical and mathematical origin of chiral properties identified in the detected signal. The analysis concludes with discussion of the magnitude of circular differential optical effects, and their potential significance for the characterization of surface-functionalized nanoparticles.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"91 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122409069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. M. Sadeghi, Waylin J Wing, K. Patty, Q. Campbell
It is well known that irradiation of colloidal quantum dots can dramatically enhance their emission efficiencies, leading to so-called photoinduced fluorescence enhancement (PFE). This process is the result of the photochemical and photophysical properties of quantum dots and the way they interact with the environment in the presence of light. It has been shown that such properties can be changed significantly using metal oxides. Using spectroscopic techniques, in this paper we investigate emission of different types of quantum dots (with and without shell) in the presence of metal oxides with opposing effects. We observed significant increase of PFE when quantum dots are deposited on about one nanometer of aluminum oxide, suggesting such oxide can profoundly increase quantum yield of such quantum dots. On the other hand, copper oxide can lead to significant suppression of emission of quantum dots, making them nearly completely dark instantly.
{"title":"Control of photoinduced fluorescence enhancement of colloidal quantum dots using metal oxides","authors":"S. M. Sadeghi, Waylin J Wing, K. Patty, Q. Campbell","doi":"10.1117/12.2188512","DOIUrl":"https://doi.org/10.1117/12.2188512","url":null,"abstract":"It is well known that irradiation of colloidal quantum dots can dramatically enhance their emission efficiencies, leading to so-called photoinduced fluorescence enhancement (PFE). This process is the result of the photochemical and photophysical properties of quantum dots and the way they interact with the environment in the presence of light. It has been shown that such properties can be changed significantly using metal oxides. Using spectroscopic techniques, in this paper we investigate emission of different types of quantum dots (with and without shell) in the presence of metal oxides with opposing effects. We observed significant increase of PFE when quantum dots are deposited on about one nanometer of aluminum oxide, suggesting such oxide can profoundly increase quantum yield of such quantum dots. On the other hand, copper oxide can lead to significant suppression of emission of quantum dots, making them nearly completely dark instantly.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122666286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. E. Sánchez Godoy, R. Rodríguez-Rojas, J. Castañeda-Contreras, V. Marañon-Ruiz, H. Pérez-Ladrón de Guevara, T. López-Luke, De la Rosa-Cruz
A technique to fabricate dye (rhodamine B) sensitized solar cells based on Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles are reported. The TiO2 was synthesized using the sol-gel method and the ZnO was synthesized by hydrolysis method to obtain nanoparticles of ~ 5 nm and 150 nm respectively. ZnO was doped with Al3+ in order to enhance the photovoltaic efficiency to promote the electrons mobility. The photovoltaic conversion characterization of films of TiO2, ZnO and ZnO:Al3+ nanoparticles is also reported. The generated photocurrent was measured by two methods; one of those uses a three electrode electrochemical cell and the other use an electronic array where the cells were exposed to UV lamp and the sun light. The role of the TiO2, ZnO and Al3+ doped ZnO nanoparticles is discussed to obtain a better efficiency in the generation of photocurrent (PC). The results exhibited by the electrochemical cell method, efficiencies of 0.55 (PC=187 μA/cm2) and 0.22 (PC=149 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44. While using the electronic array the results exhibited efficiencies of 0.31 (PC=45 μA/cm2) and 0.09 (PC=16 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44 and 0.48 for electrochemical cell and electronic array respectively. This shows that Al3+ enhances the photogenerated charge carriers increasing the mobility of electrons.
{"title":"Photovoltaic study of dye sensitized solar cells based on TiO2, ZnO:Al3+ nanoparticles","authors":"H. E. Sánchez Godoy, R. Rodríguez-Rojas, J. Castañeda-Contreras, V. Marañon-Ruiz, H. Pérez-Ladrón de Guevara, T. López-Luke, De la Rosa-Cruz","doi":"10.1117/12.2188677","DOIUrl":"https://doi.org/10.1117/12.2188677","url":null,"abstract":"A technique to fabricate dye (rhodamine B) sensitized solar cells based on Titanium Oxide (TiO2) and Zinc Oxide (ZnO) nanoparticles are reported. The TiO2 was synthesized using the sol-gel method and the ZnO was synthesized by hydrolysis method to obtain nanoparticles of ~ 5 nm and 150 nm respectively. ZnO was doped with Al3+ in order to enhance the photovoltaic efficiency to promote the electrons mobility. The photovoltaic conversion characterization of films of TiO2, ZnO and ZnO:Al3+ nanoparticles is also reported. The generated photocurrent was measured by two methods; one of those uses a three electrode electrochemical cell and the other use an electronic array where the cells were exposed to UV lamp and the sun light. The role of the TiO2, ZnO and Al3+ doped ZnO nanoparticles is discussed to obtain a better efficiency in the generation of photocurrent (PC). The results exhibited by the electrochemical cell method, efficiencies of 0.55 (PC=187 μA/cm2) and 0.22 (PC=149 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44. While using the electronic array the results exhibited efficiencies of 0.31 (PC=45 μA/cm2) and 0.09 (PC=16 μA/cm2) for TiO2 and undoped ZnO respectively. However, when ZnO is doped with Al3+ at the higher concentration the efficiency was 0.44 and 0.48 for electrochemical cell and electronic array respectively. This shows that Al3+ enhances the photogenerated charge carriers increasing the mobility of electrons.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"216 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122610093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Kanouni, A. Brézini, R. Graine, F. Arab, A. Assali
Transmissions and resonant tunneling of two-dimensional (2D) photonic superlattices (PhSLs) are discussed. We consider PhSL composed of two alternating 2D-photonic crystals. The structure is denoted as A/B/A/B……A/B, where photonic crystals A and B act as photonic wells and barriers, respectively. The transmission coefficient is calculated using the Transfer Matrix Method (TMM) in combination with Bloch theorem. The transmission spectra of the PhSLs indicate that the formation of photonic miniband and minigap inside the wells. The positions and number of the minibands can be artificially tuned by varying the well width. By appropriately choosing the structure parameters, these interesting results can be used to develop new photonic devices.
{"title":"Resonant tunneling in 2D-photonic superlattices","authors":"F. Kanouni, A. Brézini, R. Graine, F. Arab, A. Assali","doi":"10.1117/12.2185923","DOIUrl":"https://doi.org/10.1117/12.2185923","url":null,"abstract":"Transmissions and resonant tunneling of two-dimensional (2D) photonic superlattices (PhSLs) are discussed. We consider PhSL composed of two alternating 2D-photonic crystals. The structure is denoted as A/B/A/B……A/B, where photonic crystals A and B act as photonic wells and barriers, respectively. The transmission coefficient is calculated using the Transfer Matrix Method (TMM) in combination with Bloch theorem. The transmission spectra of the PhSLs indicate that the formation of photonic miniband and minigap inside the wells. The positions and number of the minibands can be artificially tuned by varying the well width. By appropriately choosing the structure parameters, these interesting results can be used to develop new photonic devices.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"136 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116532790","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Epsilon-near-zero (ENZ) metamaterials are designed to exhibit a near-zero response for the real part of the dielectric permittivity at a given frequency or in a specific frequency range. Typically, this frequency range is relatively small. In this paper, we present an approach to broaden this range by controlling the size of the nanoparticles embedded in a thin film. Noble metal nanoparticles exhibit an external size effect that redshifts the Surface Plasmon Resonance frequency with an increase of the size of the particles. The absorption spectrum of a material can be directly related to its dielectric permittivity via the Kramers-Kronig relations. We use the Kramers-Kronig relations to retrieve the complex effective dielectric permittivity of a composite film, which is designed to exhibit ENZ behavior over a broad frequency range. We synthesize a composite thin film embedded with metal nanoparticles of a broad size distribution. Such a material exhibits a broad SPR, and, in turn, broadband ENZ behavior.
{"title":"Broadband epsilon-near-zero metamaterials based on metal-polymer composite thin films","authors":"P. Pinchuk, K. Jiang","doi":"10.1117/12.2187283","DOIUrl":"https://doi.org/10.1117/12.2187283","url":null,"abstract":"Epsilon-near-zero (ENZ) metamaterials are designed to exhibit a near-zero response for the real part of the dielectric permittivity at a given frequency or in a specific frequency range. Typically, this frequency range is relatively small. In this paper, we present an approach to broaden this range by controlling the size of the nanoparticles embedded in a thin film. Noble metal nanoparticles exhibit an external size effect that redshifts the Surface Plasmon Resonance frequency with an increase of the size of the particles. The absorption spectrum of a material can be directly related to its dielectric permittivity via the Kramers-Kronig relations. We use the Kramers-Kronig relations to retrieve the complex effective dielectric permittivity of a composite film, which is designed to exhibit ENZ behavior over a broad frequency range. We synthesize a composite thin film embedded with metal nanoparticles of a broad size distribution. Such a material exhibits a broad SPR, and, in turn, broadband ENZ behavior.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124150999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. G. Ortega-Mendoza, C. Hernández-Álvarez, A. Padilla-Vivanco, C. Toxqui-Quitl, P. Zaca-Morán, F. Chávez, O. Goiz
An optical method to obtain a colloidal solution starting from a mixture of silver nanopowder and ethanol is presented. The particles of the silver nanopowder do not exhibit a specific shape, however in the colloidal solution are spherical. This method is carry out when the mixture is irradiated with a pulsed laser at 532 nm via optical fiber. Due to a stronger absorption of the laser light by silver nanoparticles arise both photofragmentation and photomelting processes. The photomelting process starts when the laser energy is 5 mJ/cm2, inducing an enlargement of nanoparticles whereas the photofragmentation occurs when the laser energy is 25 mJ/cm2 causing a reduction on their sizes (the higher energy is, the smaller nanoparticles are). Results show that it is possible to obtain a colloidal silver solution and to control the particle size by adjusting the laser energy. Experiments were performed at 5 and 25 mJ/cm2, and the results are presented.
{"title":"Photomelting and photofragmentation of silver nanoparticles suspended in ethanol","authors":"J. G. Ortega-Mendoza, C. Hernández-Álvarez, A. Padilla-Vivanco, C. Toxqui-Quitl, P. Zaca-Morán, F. Chávez, O. Goiz","doi":"10.1117/12.2188730","DOIUrl":"https://doi.org/10.1117/12.2188730","url":null,"abstract":"An optical method to obtain a colloidal solution starting from a mixture of silver nanopowder and ethanol is presented. The particles of the silver nanopowder do not exhibit a specific shape, however in the colloidal solution are spherical. This method is carry out when the mixture is irradiated with a pulsed laser at 532 nm via optical fiber. Due to a stronger absorption of the laser light by silver nanoparticles arise both photofragmentation and photomelting processes. The photomelting process starts when the laser energy is 5 mJ/cm2, inducing an enlargement of nanoparticles whereas the photofragmentation occurs when the laser energy is 25 mJ/cm2 causing a reduction on their sizes (the higher energy is, the smaller nanoparticles are). Results show that it is possible to obtain a colloidal silver solution and to control the particle size by adjusting the laser energy. Experiments were performed at 5 and 25 mJ/cm2, and the results are presented.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123218464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advanced power generation technologies including solid oxide fuel cells require advancements in sensor technologies for efficient operation. Gas sensors for SOFC anode streams must be stable in high temperature and under reducing atmospheres. Optical sensing technologies offer the potential for good stability and sensing response under harsh conditions but are relatively new as compared to alternative sensing approaches and require significant developments in underlying device and enabling materials technology. In this paper, the near infrared optical sensing response of La0.8Sr0.2MnO3, a representative correlated perovskite material, is presented. Hydrogen sensing performance was measured in laboratory scale sensing experiments in the range of 1-4% hydrogen. The effect of oxygen on sensor recovery behavior was also examined. The films show a large, recoverable response to the introduction of hydrogen to the gas stream. The results presented here suggest this unique class of materials is a strong candidate for future sensor development efforts targeted at optical sensor applications but also requires additional fundamental research to understand the mechanistic origin of observed optical sensing responses.
{"title":"Correlated electron perovskite films for optical sensing applications","authors":"A. Schultz, T. D. Brown, P. Ohodnicki","doi":"10.1117/12.2188924","DOIUrl":"https://doi.org/10.1117/12.2188924","url":null,"abstract":"Advanced power generation technologies including solid oxide fuel cells require advancements in sensor technologies for efficient operation. Gas sensors for SOFC anode streams must be stable in high temperature and under reducing atmospheres. Optical sensing technologies offer the potential for good stability and sensing response under harsh conditions but are relatively new as compared to alternative sensing approaches and require significant developments in underlying device and enabling materials technology. In this paper, the near infrared optical sensing response of La0.8Sr0.2MnO3, a representative correlated perovskite material, is presented. Hydrogen sensing performance was measured in laboratory scale sensing experiments in the range of 1-4% hydrogen. The effect of oxygen on sensor recovery behavior was also examined. The films show a large, recoverable response to the introduction of hydrogen to the gas stream. The results presented here suggest this unique class of materials is a strong candidate for future sensor development efforts targeted at optical sensor applications but also requires additional fundamental research to understand the mechanistic origin of observed optical sensing responses.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126275563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Gerard, Joseph Govan, A. Loudon, A. Baranov, A. Fedorov, Y. Gun’ko
The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.
{"title":"Optically active quantum dots","authors":"V. Gerard, Joseph Govan, A. Loudon, A. Baranov, A. Fedorov, Y. Gun’ko","doi":"10.1117/12.2187198","DOIUrl":"https://doi.org/10.1117/12.2187198","url":null,"abstract":"The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129294529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ByoungChang Kim, Sang-Jo Kim, Somi Kang, Sangjoon Moon, Eun-Hye Park, K. Kang
Polyaniline (PAn)-coated silica spheres have been synthesized by attaching various amounts of N-[3- (trimethoxysilyl)propyl]aniline (TMSPA) and polymerizing with ammonium persulfate. The ratios of tetraethoxy orthosilicate and TMSPA were 10:1 (PAn-A), 5:1 (PAn-B), and 3:1 (PAn-C). After polymerization of the aniline moieties the –OH absorption peak drastically reduced and the new sharp peaks appeared at 1398 cm-1 and 617 cm-1 representing C-N and C-S stretching vibrations, respectively. The polymerized spheres were soaked into the acetone for three months. New absorption peak at 1712 cm-1 representing C=O stretching vibration of an ester appears after three months storage in acetone and becomes stronger with the smaller amount of PAn. Although the sphere film color is gray when it is dried, the color turned to dark when it was wetted with methanol. Complicated solvatochromic behavior was observed for whole UV-visible range depending on the solvent. The solution color changed from clear to dark brown, brown, and yellow for the PAnA, PAnB and PAnC, respectively. The absorption peaks of the dried solution for PAn-A and PAn-B at 3230, 2972, 2926, 1712, 1434/1377, and 1051 cm-1 represent C-OH, R-CH3, R2-CH2, -C=O, C-H, and Si- O-Si absorption, respectively. Photoluminescence peak of the solution shifted toward longer wavelength with the decrease the amount of PAn. The sequence of the amount of new material formation is PAn-A > PAn-B > PAn-C.
{"title":"Optical properties of polyaniline-coated silica spheres: aging effect in acetone","authors":"ByoungChang Kim, Sang-Jo Kim, Somi Kang, Sangjoon Moon, Eun-Hye Park, K. Kang","doi":"10.1117/12.2187587","DOIUrl":"https://doi.org/10.1117/12.2187587","url":null,"abstract":"Polyaniline (PAn)-coated silica spheres have been synthesized by attaching various amounts of N-[3- (trimethoxysilyl)propyl]aniline (TMSPA) and polymerizing with ammonium persulfate. The ratios of tetraethoxy orthosilicate and TMSPA were 10:1 (PAn-A), 5:1 (PAn-B), and 3:1 (PAn-C). After polymerization of the aniline moieties the –OH absorption peak drastically reduced and the new sharp peaks appeared at 1398 cm-1 and 617 cm-1 representing C-N and C-S stretching vibrations, respectively. The polymerized spheres were soaked into the acetone for three months. New absorption peak at 1712 cm-1 representing C=O stretching vibration of an ester appears after three months storage in acetone and becomes stronger with the smaller amount of PAn. Although the sphere film color is gray when it is dried, the color turned to dark when it was wetted with methanol. Complicated solvatochromic behavior was observed for whole UV-visible range depending on the solvent. The solution color changed from clear to dark brown, brown, and yellow for the PAnA, PAnB and PAnC, respectively. The absorption peaks of the dried solution for PAn-A and PAn-B at 3230, 2972, 2926, 1712, 1434/1377, and 1051 cm-1 represent C-OH, R-CH3, R2-CH2, -C=O, C-H, and Si- O-Si absorption, respectively. Photoluminescence peak of the solution shifted toward longer wavelength with the decrease the amount of PAn. The sequence of the amount of new material formation is PAn-A > PAn-B > PAn-C.","PeriodicalId":432358,"journal":{"name":"SPIE NanoScience + Engineering","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129252635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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