Download or read book Fabrication of Surface Enhanced Raman Scattering Substrates by Controlled Assembly and Morphology Tuning of Gold Nanoparticles written by Agampodi Swarnapali De Silva Indrasekara and published by . This book was released on 2014 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design and fabrication of nanoparticles (NPs) and NP assemblies to sustain intense electromagnetic field enhancement for surface enhanced Raman scattering (SERS)-based imaging and sensing have recently gained significant attention. In SERS, the intrinsic optical properties of plasmonic NPs are used to overcome the relatively low Raman cross-sections and thereby increase sensitivity. Sharp features in anisotropic NPs and interparticle gaps within NP assemblies have been identified as the locations where the highest SERS enhancements can be achieved, also known as "hot spots". Many attempts have been reported that deal with the bottom-up assembly of NPs to achieve highly reproducible, sensitive, and well characterized SERS substrates, but it still remains a challenge to attain monodisperse, highly reproducible "hot spots" and directional assembly. The focus of this dissertation is to develop synthetic protocols for controlled engineering of NPs with SERS "hot spots", and thereby to contribute to the advancement of SERS-based sensing and imaging applications. In this dissertation, the development of SERS substrates has evolved from dimers of spherical gold NPs (SP), to star-shaped gold NPs (ST), and finally to assembled superstructures of ST and SPs. The kinetically controlled assembly of SPs into dimers was achieved by using Raman active dithiolated linker molecules, with the highest yield reported for this method to the best of our knowledge, leading to SERS tags with a reproducible SERS enhancement on the order of 105. NP dimers, surface-functionalized to target U87 glioblastoma cancer cells, demonstrated a fast, reliable, and selective SERS-based detection of the diseased cells that outperforms fluorescence. The morphology of the STs was modified to possess longer and sharper spikes with a narrower tip curvature thereby increasing the electromagnetic field localization at the tips. SERS substrates were designed by periodically and reproducibly immobilizing STs on a planar substrate with high surface coverage and limited to no clustering, thus enabling femtomolar detection of organic analytes with an outstanding 109 SERS enhancement. Finally, the core-satellite assemblies of ST with SPs were achieved through conjugation linker chemistry. These assemblies demonstrated SERS enhancement of two orders of magnitudes greater than isolated STs thereby improving the sensitivity of potential SERS-based imaging and sensing applications.
Download or read book Fabrication Characterization and Optical Properties of Three dimensional Colloidal Gold Nanostructures written by Christopher James Addison and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 3-Dimensional nanostructures were constructed through the alternate immersion of aderivatized glass slide in solutions of propanedithiol and gold nanoparticles. The size andshape of the surface features could be controlled based on the number of nanoparticledepositions. Characterization of the substrates was performed using W-Visspectroscopy and atomic force microscopy. The multilayer nanoparticle substrates wereexamined for their suitability in surface-enhanced Raman scattering (SERS) by obtainingthe SERS spectrum of oxazine-720 on the substrates. A dramatic increase in the SERSsignal is noted with increasing nanoparticle layers and reaches a maximum for 11nanoparticle-layer depositions. The enhancement is attributed to the underlying surfacemorphology: Surface features on the order of 40 nm in size yield the greatest SERSenhancement due to surface plasmon (SP) excitation. The non-linear optical properties of colloidal nanostructures were examined using secondharmonic generation (SHG). A pronounced second harmonic emission was noted for 13nanoparticle layers and was attributed to SP excitation to yield surface-enhanced SHG. The self-assembly of gold nanorods to form 3-dimensional nanostructures was examined. While the self-assembly was not successful, the aggregated gold nanorods exhibited alarge SERS enhancement. This suggests that the incorporation of gold nanorods intoSERS substrates is a viable avenue for future research.
Download or read book Fabrication Characterization and Optical Properties of Three dimensional Colloidal Gold Nanostructures written by Christopher James Addison and published by . This book was released on 2005 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: 3-Dimensional nanostructures were constructed through the alternate immersion of aderivatized glass slide in solutions of propanedithiol and gold nanoparticles. The size andshape of the surface features could be controlled based on the number of nanoparticledepositions. Characterization of the substrates was performed using W-Visspectroscopy and atomic force microscopy. The multilayer nanoparticle substrates wereexamined for their suitability in surface-enhanced Raman scattering (SERS) by obtainingthe SERS spectrum of oxazine-720 on the substrates. A dramatic increase in the SERSsignal is noted with increasing nanoparticle layers and reaches a maximum for 11nanoparticle-layer depositions. The enhancement is attributed to the underlying surfacemorphology: Surface features on the order of 40 nm in size yield the greatest SERSenhancement due to surface plasmon (SP) excitation. The non-linear optical properties of colloidal nanostructures were examined using secondharmonic generation (SHG). A pronounced second harmonic emission was noted for 13nanoparticle layers and was attributed to SP excitation to yield surface-enhanced SHG. The self-assembly of gold nanorods to form 3-dimensional nanostructures was examined. While the self-assembly was not successful, the aggregated gold nanorods exhibited alarge SERS enhancement. This suggests that the incorporation of gold nanorods intoSERS substrates is a viable avenue for future research.
Download or read book New Ultrasensitive Bimetallic Substrates for Surface Enhanced Raman Scattering written by Mohammad Yehia Khaywah and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driven by the interest in finding ultrasensitive sensors devices, reliable surface enhanced Raman scattering (SERS) based substrates are fabricated. Silver and gold nanoparticles are two of the best candidates for SERS substrates where Ag nanoparticles exhibit large enhancing ability in Raman intensity while Au nanostructures are stable in biological systems. Hence, combining the two metals in bimetallic nanostructures appeared to be a promising approach in order to sum the merits of Au surface properties and Ag enhancing ability. Thermal annealing of thin metallic films is used as a simple and relatively inexpensive technique to elaborate homogenous and reproducible Ag/Au bimetallic nanoparticles SERS substrates with high enhancing ability. The fabricated nanoparticles proved their enhancing stability even after one year of fabrication. Manipulating the composition of Ag/Au bimetallic NPs resulted in tuning the Localized Surface Plasmon Resonance (LSPR) over the whole visible spectrum, where the substrates are characterized with higher SERS enhancement when they exhibit LSPR closer to the Raman excitation wavelength. Additionally, bimetallic nanoparticles patterns with different size, composition and lattice constants have been conducted by electron beam lithography. The systematic study of their interesting plasmonic and SERS enhancing properties revealed maintenance in the LSPR-SERS relation by changing the nanoparticle size.
Download or read book Self Organized Arrays of Gold Nanoparticles written by Luca Anghinolfi and published by Springer Science & Business Media. This book was released on 2012-06-16 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses the fabrication and investigation of the optical response of gold nanoparticle arrays supported on insulating LiF(110) nanopatterned substrates. Motivated by the discovery of the intriguing effects that arise when electromagnetic radiation interacts with metallic nanostructures, the thesis focuses on the application of bottom-up approaches to the fabrication of extended-area plasmonic nanostructures, and the optimization of their optical response. By developing a sophisticated effective-medium model and comparing the experimental findings with model calculations, the author explores the role of the interparticle electromagnetic coupling and array dimensionality on the collective plasmonic behavior of the array, giving insights into the physical mechanisms governing the optical response.
Download or read book Principles of Surface Enhanced Raman Spectroscopy written by Eric Le Ru and published by Elsevier. This book was released on 2008-11-17 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: SERS was discovered in the 1970s and has since grown enormously in breadth, depth, and understanding. One of the major characteristics of SERS is its interdisciplinary nature: it lies at the boundary between physics, chemistry, colloid science, plasmonics, nanotechnology, and biology. By their very nature, it is impossible to find a textbook that will summarize the principles needed for SERS of these rather dissimilar and disconnected topics. Although a basic understanding of these topics is necessary for research projects in SERS with all its many aspects and applications, they are seldom touched upon as a coherent unit during most undergraduate studies in physics or chemistry. This book intends to fill this existing gap in the literature. It provides an overview of the underlying principles of SERS, from the fundamental understanding of the effect to its potential applications. It is aimed primarily at newcomers to the field, graduate students, researchers or scientists, attracted by the many applications of SERS and plasmonics or its basic science. The emphasis is on concepts and background material for SERS, such as Raman spectroscopy, the physics of plasmons, or colloid science, all of them introduced within the context of SERS, and from where the more specialized literature can be followed. Represents one of very few books fully dedicated to the topic of surface-enhanced Raman spectroscopy (SERS) Gives a comprehensive summary of the underlying physical concepts around SERS Provides a detailed analysis of plasmons and plasmonics
Download or read book Surface Enhanced Vibrational Spectroscopy written by Ricardo Aroca and published by John Wiley & Sons. This book was released on 2006-05-01 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface Enhanced Vibrational Spectroscopy (SEVS) has reached maturity as an analytical technique, but until now there has been no single work that describes the theory and experiments of SEVS. This book combines the two important techniques of surface-enhanced Raman scattering (SERS) and surface-enhanced infrared (SEIR) into one text that serves as the definitive resource on SEVS. Discusses both the theory and the applications of SEVS and provides an up-to-date study of the state of the art Offers interpretations of SEVS spectra for practicing analysts Discusses interpretation of SEVS spectra, which can often be very different to the non-enhanced spectrum - aids the practicing analyst
Download or read book Deep Eutectic Solvents written by Diego J. Ramón and published by John Wiley & Sons. This book was released on 2020-01-13 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: A useful guide to the fundamentals and applications of deep eutectic solvents Deep Eutectic Solvents contains a comprehensive review of the use of deep eutectic solvents (DESs) as an environmentally benign alternative reaction media for chemical transformations and processes. The contributors cover a range of topics including synthesis, structure, properties, toxicity and biodegradability of DESs. The book also explores myriad applications in various disciplines, such as organic synthesis and (bio)catalysis, electrochemistry, extraction, analytical chemistry, polymerizations, (nano)materials preparation, biomass processing, and gas adsorption. The book is aimed at organic chemists, catalytic chemists, pharmaceutical chemists, biochemists, electrochemists, and others involved in the design of eco-friendly reactions and processes. This important book: -Explores the promise of DESs as an environmentally benign alternative to hazardous organic solvents -Covers the synthesis, structure, properties (incl. toxicity) as well as a wide range of applications -Offers a springboard for stimulating critical discussion and encouraging further advances in the field Deep Eutectic Solvents is an interdisciplinary resource for researchers in academia and industry interested in the many uses of DESs as an environmentally benign alternative reaction media.
Download or read book Controlled Assembly of Metal Nanoparticles with Enhanced Optical Properties written by Zhaoxia Qian and published by . This book was released on 2014 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Controlled synthesis of metal nanoparticles is an important area of study because of the unique size and shape dependent properties of such nanoparticles. For example, gold and silver nanoparticles show distinct surface Plasmon resonance (SPR) bands varying with the size, shape and surface morphology of the nanoparticles. The assembly of these nanoparticles usually exhibit interesting collective optical properties different from their individual components. However, controlled synthesis and assembly of metal nanoparticles with high yield and enhanced optical properties is still challenging. In this thesis, I presented the synthesis of ultrathin gold/silver nanowires and sub-50 nm gold triangular nanoprisms by adopting silver seeds and benzyl dimethyl hexadecyl ammonium chloride (BDAC) in a seed-mediated growth method. Furthermore, I developed a templated surfactant-assisted seed growth method to synthesize gold nanoshells with varying surface morphologies by changing the type of surfactants and ions in the growth solution. The optical properties of the nanoshells could be controlled over a wide wavelength range by varying the surface morphology. By using a combination of BDAC surfactant and template surfactant-assisted seed growth method, isotropic shell-type gold nanoparticle clusters, or raspberry-like meta-molecules (raspberry-MMs), were successfully synthesized. The raspberry-MMs exhibited interesting far field and near field optical properties. The raspberry-MMs showed unusually strong magnetic resonances, yielding broad SPR bands in the visible and near-IR region. Both experimental data and finite-difference time-domain (FDTD) simulations showed that the magnetic dipole can be even larger than that of the electric dipole resonance in large raspberry-MMs. Moreover, I utilized Raman spectroscopy as a tool to probe the near field optical properties of the raspberry-MMs. Due to the existence of a large number of hotspots at the gaps among gold beads within individual raspberry-MMs, individual raspberry-MMs proved to be efficient Raman substrate. Importantly, the contribution from hotspots created at the gap between two adjacent raspberry-MMs is negligible compared to that from a large number of hotspots on individual raspberry-MMs. Consequently, the Raman signal intensity of the analyte molecules on the raspberry-MM dimers exhibited quite narrow distribution and is weakly dependent on the distance between the two raspberry-MMs. This paved the way for fabricating large-area raspberry-MM films which can serve as macroscopic efficient and reproducible Raman substrate. The robustness and tunability of the synthetic method presented in this thesis, the strong magnetic responses of the raspberry-MMs and the efficient Raman enhancement from single raspberry-MM, raspberry-MM dimer and films can lead to large-scale manufacture and wide applications of magnetic metamaterials as well as commercialization of uniform Raman substrate.
Download or read book The Rational Design and Lithographic Fabrication of Surface Enchanced i e Enhanced Raman Spectroscopy Substrates written by and published by . This book was released on 2008 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analytical capabilities of surface-enhanced Raman spectroscopy (SERS) reside in the performance characteristics of the SERS-active substrate. Signal enhancement observed in SERS is attributable to the presence of noble metal nanostructures on substrate surfaces. The rational design and control of variables such as shape and size, and distribution, density, and spacing of these nanostructures can lead to substrates that have greater analytical sensitivity and yield more reproducible enhancement. Through systematic control of the morphology of our SERS substrates, we have created ordered periodic arrays as well as random aggregates of nanoscale particles using electron beam lithography (EBL). A unique aspect of these EBL-created substrates is that the morphology is known with great precision. Once fabricated, the arrays and/or aggregates are coated with a SERS-active noble metal through physical vapor deposition (PVD). Both the uniform and random lithographically produced nanopatterns are studied by surface enhanced Raman spectroscopy to examine the Stokes responses of various analytes, while scanning electron microscopy (SEM) is used to examine pattern surfaces post lithographic development and post noble metal deposition. In the case of the ordered structures, raw and normalized SERS data is seen to correlate with data from simple electrostatic calculations as well as the broad background continuum underlying each spectrum collected. Borrowing from the biological concepts of cloning and combinatorial chemistry, random morphology patterns are designed and spectrally mapped to locate "hot spots" within aggregates. Regardless of the type of substrate, ordered or random, by using EBL, the substrates can be reproducibly fabricated, yielding consistent analyte environments each time the substrate is created.
Download or read book Fabrication of Surface Enhanced Raman Scattering SERS Substrates Made from Nanoparticle Printing Inks for Detection of Biological Molecules written by Manuel Alejandro Figueroa and published by . This book was released on 2013 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface enhanced Raman scattering ΔΟΠ� ϝαπ ϛδλδοαϟδγ ϛοδαϟ ζλϟδοδπϟ απ α προεαϐδ αλαιυϟζϐαι ϟδϐϝλζξρδ βδϐαρπδ ζϟ ϐαλ νομγρϐδ ακνιζεζϐαϟζμλ εαϐϟμοπ βδϟςδδλ »«��»«»“� Πζισδο αλγ ϛμιγ αοδ ϟϝδ κμπϟ ςζγδιυ ρπδγ ϐμκνμλδλϟπ απ ϟϝδζο πζφδ αλγ πϟορϐϟροδ αιιμςπ εμο ιζϛϝϟ ϟμ ζλγρϐδ ϐμλγρϐϟζμλ διδϐϟομλπ ϟμ μπϐζιιαϟδ ιμϐαιιυ ςζϟϝζλ ϟϝδ λαλμναοϟζϐιδ πϟορϐϟροδ� �ϝδλ α κμιδϐριδ ιζδπ ζλ ϟϝδ ζλϟδοναοϟζϐιδ πναϐδ βδϟςδδλ ϟςμ λαλμναοϟζϐιδπ� ϝζϛϝιυ γδϟαζιδγ σζβοαϟζμλαι ζλεμοκαϟζμλ βδϐμκδπ γδϟδϐϟαβιδ� Ϟϝδ μβηδϐϟζσδ με ϟϝζπ πϟργυ ζπ ϟμ οδνομγρϐζβιυ εαβοζϐαϟδ πρϐϝ αλ αοοαλϛδκδλϟ ζλ α λαλμναοϟζϐιδ πρβπϟοαϟδ ςϝζιδ καζλϟαζλζλϛ πϟαβζιζϟυ� Ζλ ϟϝζπ ςμοθ� λαλμναοϟζϐιδ νοζλϟζλϛ ζλθπ �� ϐμιιμζγαι λαλμναοϟζϐιδπ δλϐανπριαϟδγ βυ α πϟαβζιζφζλϛ ιζϛαλγ �� αοδ ρπδγ απ ϟϝδ καζλ ϐμκνμλδλϟ με ΠΔΟΠ πρβπϟοαϟδπ� Ϟϝδ ιζϛαλγ πϝδιι ζπ ναοϟζαιιυ οδκμσδγ βυ ϐμλϟομιιδγ ϝδαϟζλϛ� ςϝζϐϝ οδγρϐδπ πναϐζλϛ βδϟςδδλ λαλμναοϟζϐιδπ ϐοδαϟζλϛ α βομαγ γζπϟοζβρϟζμλ με ζλϟδοναοϟζϐιδ γζπϟαλϐδπ� Πζκζιαο ϟμ εοαϐϟαι αϛϛοδϛαϟδπ ϟϝζπ αοοαλϛδκδλϟ αιιμςπ ιμϐαιζφδγ νιαπκμλπ ϟμ λαϟροαιιυ οδπμλαϟδ μσδο α βομαγ οαλϛδ με πνδϐϟοαι εοδξρδλϐζδπ� Κζϐομςασδ αβπμονϟζμλ ζπ αννιζδγ απ α λμλ�ζλσαπζσδ κδϟϝμγ ϟμ πδλπζϟζσδιυ κμλζϟμο λαλμναοϟζϐιδ πζλϟδοζλϛ ζλ μογδο ϟμ ϛαρϛδ ϟϝδ πρβπϟοαϟδπ ͅϟρλζλϛ εμο ιαοϛδ ακνιζεζϐαϟζμλ εαϐϟμοπ� Ϟϝδ ϛιμβαι αοοαλϛδκδλϟ με λαλμναοϟζϐιδπ ϝαπ αιςαυπ βδδλ γζεεζϐριϟ ϟμ κδαπροδ γροζλϛ ϝδαϟζλϛ ϟϝομρϛϝ Γ� οδπζπϟζσζϟυ κδαπροδκδλϟπ αλγ προεαϐδ ζκαϛζλϛ ϟδϐϝλζξρδπ� Κζϐομςασδ αβπμονϟζμλ μϐϐροπ ζλ ϟϝδ ςδαθ οδπζπϟζσδ ιζλθπ εμοκδγ βδϟςδδλ ναοϟζϐιδπ γροζλϛ πζλϟδοζλϛ γρδ ϟμ ϟϝδ κζϐομςασδ ιμππδπ ζλ ιμμπδιυ ϐμρνιδγ ναοϟζϐιδπ� Βυ νιαϐζλϛ ϟϝδ πρβπϟοαϟδ ζλ α κζϐομςασδ ϐασζϟυ� αβπμονϟζμλ ϐαλ βδ κμλζϟμοδγ ϛιμβαιιυ γροζλϛ ϝδαϟζλϛ� Ϟϝδ ιαοϛδπϟ ΠΔΟΠ ακνιζεζϐαϟζμλ εαϐϟμοπ μϐϐρο αϟ α πϟαϛδ ζκκδγζαϟδιυ νοδϐδγζλϛ ϟϝδ ιαοϛδπϟ κζϐομςασδ αβπμονϟζμλ ϛαζλπ� Ϟϝζπ νομσζγδπ α ρπδερι κδϟϝμγ εμο γδϟδοκζλζλϛ α ϟϝδοκαι ςζλγμς εμο ϝδαϟζλϛ ςϝδλ μνϟζκζφζλϛ ΠΔΟΠ πρβπϟοαϟδπ� Εζλαιιυ� ϟϝδπδ μνϟζκζφδγ ΠΔΟΠ πρβπϟοαϟδπ αοδ ρπδγ ϟμ γδϟδϐϟ ϝυαιρομλζϐ αϐζγ� Ϟϝζπ ϐμκνιδτ κμιδϐριδ ζπ α νμϟδλϟζαι βζμκαοθδο εμο ζλειακκαϟμου γζπδαπδπ βρϟ ζϟ ϝαπ μλιυ βδδλ γδϟδϐϟδγ αϟ α ϐμλϐδλϟοαϟζμλ με ͵ κϛ�κΙ μλ ϐμκκδοϐζαιιυ ασαζιαβιδ ΠΔΟΠ πρβπϟοαϟδπ� Ϝδοδ ζϟ ζπ πϝμςλ ϟϝαϟ ερλϐϟζμλαιζφζλϛ ϟϝδ ΠΔΟΠ πρβπϟοαϟδ ςζϟϝ α πδιε�αππδκβιδγ κμλμιαυδο ιμςδοπ ϟϝδ ιζκζϟ με γδϟδϐϟζμλ ϟμ ͵« �ơϛ�κΙ� ΠΔΟΠ αλαιυπζπ αιπμ νομσζγδπ πϟορϐϟροαι γδϟαζιπ αβμρϟ ϟϝδ ϐμλεμοκαϟζμλ με ϟϝδ κμιδϐριδ γροζλϛ αγπμονϟζμλ�
Download or read book Surface enhanced Raman Scattering of Metal Nanoparticle Assembly in Agarose and Highly Ordered Metal Nanorod Arrays written by Martin Keating and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines metal nanoparticle/agarose (MNPA) gel composites and highly ordered metal nanorod arrays, fabricated by guided nucleation during oblique angle deposition (OAD), as surface-enhanced Raman scattering (SERS) substrates. The effectiveness of MNPA has been effectively demonstrated previously using silver nanoparticles (AgNPs), but it is poorly understood how different NP growth conditions affect the SERS response. SERS intensity of gold and silver NPA is examined in detail as a function of salt and (by default) reducing solution concentration, and the effect of using different reductants is also investigated; reproducibility of selected gels is carefully explored. In addition, SERS of highly ordered Ag and copper (Cu) nanoarrays is examined in depth. Normally, OAD generates a random nanorod distribution on flat supports, where nucleation is a random process. This however hinders the control of geometrical parameters such as rod separation and diameter which directly affect the SERS response, an effect mitigated by introducing a guiding element to influence nucleation. Until recently, only semiordered SERS-active Ag nanorod arrays had been accomplished by OAD. These however depended on time-consuming and expensive electron beam lithography (EBL) to write a template to guide nucleation and the subsequent growth of nanorods. Importantly, lengthy fabrication times force a practical upper size limit on the substrate, meaning it is exceedingly small which drastically reduces its potential for sensing applications. It also severely restricts the number of substrates which can be produced in a given time. This thesis addresses these issues via the construction of highly ordered, SERS-active, large-area Ag and Cu nanorod arrays, using a cheap, large-scale, nanoimprinted polymer template to influence nucleation during the initial stages of OAD. Moreover, OAD is a high throughput method, as it permits the simultaneous fabrication of several substrates during a relatively short deposition cycle.
Download or read book A Study on the Synthesis and Properties of Gold Nanoparticles and Their Applications to Surface Enhanced Raman Spectroscopy written by Daniel Robert Soden and published by . This book was released on 2016 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface enhanced Raman substrates represent a critical step in the sensitivity augmentation of Raman spectroscopy, but due to the time and expertise currently required in the synthesis process, they have not been fully realized within an industrial setting. This thesis aims to investigate a new technique in surface enhanced Raman spectroscopy (SERS) substrate fabrication designed to decrease synthesis time and map the most effective growth parameters for a successful Raman intensity boost. Sputter physical vapor deposition was utilized to deposit a gold (Au) layer on an insulating substrate, and annealing treatments were applied to agglomerate the Au atoms into the sought after nanostructures conducive to the SERS effect. Substrates were characterized with a variety of techniques including scanning electron microscopy, Raman spectroscopy, and atomic force microscopy, as well as several others. Physical morphologies of the nano features are summarized as well as their impact upon spectroscopic behavior. Surface enhanced Raman intensity boost is also documented and linked back to growth parameters in order to determine effective deposition methods for a successful SERS substrate.
Download or read book Fabrication of Hierarchical Gold Nanoblades with High Surface Enhanced Raman Scattering Activity written by Jiawei He (M.S. in Engineering) and published by . This book was released on 2017 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: To obtain high sensitivity, efficiency, reproducibility and specificity, has been the goal in biochemical detection. Surface enhanced Raman scattering (SERS), which utilizes localized surface plasmon resonance (LSPR) of noble metals to significantly enhance Raman signals of molecules, is one of the most promising techniques for bio-sensing. Silver has been the dominant substrates for SERS due to its ultrahigh sensitivity. Comparing to silver, gold has its advantages in better bio-compatibility, less toxicity, and more tunable surface plasmon resonance (SPR) properties for potential photothermal applications in cancer treatment. Developing spiky gold nanostructures with sharp tips and dense junctions is the key to making its SERS performance comparable to silver. In this study, the synthesis of Au nanoblades for SERS activity with high sensitivity has been explored. By utilizing the galvanic replacement reaction between chloroauric acid (HAuCl4) and Ag nanocapsules with 3,4-dihydroxyphenylalanine (DOPA) as surfactant and reducing agent, a new spiky structure of Au nanoblades coated on Ag nanocapsules was successfully synthesized. The concentration of DOPA and reaction time can significantly affect the number and morphology of Au blades. The lengths of Au nanoblades can vary from 20 nm to 100 nm under different reaction conditions. The SEM and EDS results have demonstrated the mechanism of the growth of Au nanoblades and the role of DOPA. The formation of AgCl during galvanic reaction between HAuCl4 and Ag nanoparticles can promote non-epitaxial growth of Au on the AgCl precipitates. DOPA serves as a reducing agent to reduce HAuCl4 to Au and a capping agent to favor the growth of sharp tips. Raman test results showed that the Au nanoblades detected Raman spectra of Nile blue with a concentration as low as 10−10 M. The high sensitivity and detection limit can be attributed to the dense sharp tips and small junctions as hotspots along the whole surface of the nanocapsules, which is comparable to the state-of-the-art Ag SERS substrates
Download or read book Surface Enhanced Raman Spectroscopy written by Sebastian Schlücker and published by John Wiley & Sons. This book was released on 2011-09-19 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.
Download or read book Surface Enhanced Raman Scattering written by Zhong-Qun Tian and published by John Wiley & Sons Incorporated. This book was released on 2010-06-14 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface-Enhanced Raman Spectroscopy: Principles, Experiments, and Applications is a comprehensive, up to date, and balanced treatment of the theoretical and practical aspects of Surface-Enhanced Raman Scattering (SERS), a useful branch of spectroscopy for several areas of science. This book describes the basic principles of SERS, including SERS mechanisms, performing SERS measurements, and interpreting data. Also emphasized are applications in electrochemistry; catalysis; surface processing and corrosion; Self-Assemble-Layer and L-B Films; polymer science; biology; medicine and drug analysis; sensors; fuel cells; forensics; and archaeology. It is an essential guide for student and professional analytical chemists.
Download or read book Nanomanufacturing of Gold Nanoparticle Superstructures from the bottom up written by Tingling Rao and published by . This book was released on 2013 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gold nanoparticles that can generate surface plasmons under appropriate conditions have attracted significant interest for their potential in optics, photonics, data storage and biological sensors. Developing high fidelity fabrication methods that yield gold nanoparticles with well-defined size, shape, composition and self-assembly allows manipulation of surface plasmonic properties for novel applications as well as revealing new aspects of the underlying science. This dissertation demonstrates multiple techniques that describe cost-effective "bottom-up" fabrication methods that yield gold nano-superstructures. In my initial work, I outline the solution conditions for fabricating Janus nanoparticles composed of one gold nanoparticle per micelle. Poly(ethylene oxide)-b-polystyrene (PEO-b-PS) was synthesized and processed into spherical micelles, which served as the template to induce gold nanoparticles growth within the PEO corona in situ. Organic-inorganic hybrid nanoparticle formation was controlled kinetically by manipulating the concentration of both the micelle and reducing agent (HEPES). We also found that under certain condition, PEO-b-PS yielded micelles with pearl-like morphology, which possessed concentrated PEO domains at the interface between two adjacent PS cores. Careful manipulation of reaction conditions afforded gold nanoparticles that grew from the core-shell interface to form 1-dimensional (1-D) periodical gold nanoparticle chains. Based on similar principles, gold-gold dimers were synthesized by growing a second gold nanoparticle from a gold nanoparticle template surface-functionalized with PEO ligands. Gold dimers fabricated with this method exhibited strong enhancement properties via surface-enhanced Raman scattering (SERS). Instead of kinetic control, the number of newly grown gold nanoparticles on each particle template heavily relied on the PEO density on the nanoparticle template. As the size of the particle template increased from 10 nm to 48 nm, the corresponding number of PEO chains on each particle was estimated to increase proportionally from 6 to 140. Consequently, the structure of the final products could be manipulated from gold dimer to raspberry-like structures. The third part of my work demonstrated the fabrication of 2-dimensional (2-D) gold nanoparticle arrays using peptide-derivatized block copolymer thin film templates. A triblock polystyrene-b-poly(methyl methacrylate)-b-A3 peptide (PS-b-PMMA-A3) was synthesized and processed into thin film with highly-ordered surface patterns via cold zone annealing (CZA). Gold nanoparticles were selectively immobilized onto PMMA domains due to the binding affinity of A3 peptide located at the PMMA chain end. Gold nanoparticle structures such as hexagonally-packed gold nanoparticle clusters and parallel gold nanoparticle wires have been achieved using this method. GISAXS results indicate that the hexagonal gold-hierarchical structure is constituted of two different structures: a primary structure induced by nanofeatures on the thin film template and a secondary structure formed through gold nanoparticle packing within each cluster domain. Selectivity of the thin film template to gold nanoparticles and the nanoparticle aggregation are two competing phenomena that affect resolution of the hierarchical structures.
