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Plasmonics can achieve the tight optical confinement and localization in the subwavelength domain. Surface plasmon polaritons (SPPs) are closely related to coupling to emitters in excitation and emission, waveguiding, and active modulating on the nanoscale. Due to these phenomenon, plasmonic nanostructures can be used for applications, such as light emission, photodetection, optical sensing, and spectroscopy. Conventional plasmonic nanostructures can support plasmonic modes, and it is typically optimized for a single wavelength window with planar plasmonic structures. Recent studies have reported some in-plane composite nanostructures and core-shell geometries can induce multiple plasmonic responses. However, it is challenging to achieve the control of individual plasmonic response due to the interdependent spectral tunability with changes in their in-plane geometries. In this dissertation, the concept of out-of-plane engineered nanoantenna structures is introduced, numerically calculated, and experimentally demonstrated. The nanolaminated MIM plasmonic structures show multiresonant plasmonic responses in the same antenna and each wavelength band can be tunable individually with different thicknesses of dielectric layers. The nanolaminated plasmonic structures has been reported for a scalable Surface-enhanced Raman spectroscopy (SERS) substrate for single-molecule sensitive and label-free chemical analysis. Due to the strong optical field confinement, the nanolaminated SERS substrates achieve increased SERS enhancement factor (EF) up to 1.6 x 108 with proper partial etching of dielectric layers. Furthermore, the nanolaminated MIM plasmonic structures have been successfully integrated with micro-scale pillar arrays to control the surface wettability for ultrasensitive SERS measurements. The hierarchical micro/nano plasmonic surface has densely packed intrinsic SERS-active hot spots that give rise to SERS EFs exceeding 107. This platform can take full advantage of low surface energy to control and measure the analyte in water droplets. Leidenfrost evaporation-assisted SERS sensing on the hierarchical substrates provides the way for ultrafast and ultrasensitive biochemical detections without a need for additional surface modifications and chemical treatments. / Doctor of Philosophy / The life in the 21th century has benefited from the technical revolutions of computational power that is based on the manipulation/storage of electrons. As predicted in Moore's law, the size of electronic microchip would go down, and the computational power has been enhanced due to the increase of transistor integration density. However, the two major factors, such as energy dissipation of electrons and signal delay of electronic circuit, limit the communication speed of electronics. These barriers have caused slowdown in the performance of computational power. Photonic solutions have been offered to solve the limitations based on the larger bandwidth and a rare energy dissipation, compared to electronic counterparts. Moreover, optical communications typically demand much lighter channel to deliver similar power/information than practical electrical cables do. Thus, light manipulation/enhancement techniques are envisioned to overcome the limitations and guide to the methodology of interconnections between the electronic circuits and optical platforms. Plasmonics can achieve the nanoscale light confinement and localization in the subwavelength domain. This strong confinement is originated from the coupling between the photons and the electron gas on the metal that results in surface plasmon polariton (SPP). SPPs are closely related to coupling to emitters in excitation and emission, waveguiding, and active modulating on the nanoscale. Due to these phenomenon, plasmonic nanostructures can be used for applications, such as light emission, photodetection, optical sensing, and spectroscopy. In this dissertation, the concept of out-of-plane engineered nanoantenna structures is introduced, numerically calculated, and experimentally demonstrated. This vertically stacked nanoantenna structure is composed of metal-insulator-metal (MIM) laminates fabricated by physical vapor deposition techniques. Although conventional plasmonic nanostructures can support plasmonic modes, it is typically optimized for a single wavelength window. The nanolaminated MIM nanostructures, by contrast, can induce multiresonant plasmonic response in the same antenna with several advantages: (1) reduced individual footprint size and volume of nanoantenna, (2) accurate control of layer thicknesses by thin film deposition technique for resonance tuning, (3) easier integration with other functional materials as gap layers, and (4) efficient transport of charge carriers or heat in nanolaminated layers. As a result of the tight optical field confinement, the nanolaminated plasmonic structures can be used for sensing application called Surface-enhanced Raman spectroscopy (SERS), which is a promising sensing platform for label-free biochemical analysis at the single-molecule level. Partial oxide etching process enables the analyte molecules to accommodate in strong enhancement region of the nanolaminated structures, resulting in amplified unique Raman features of molecular compounds as a finger print. The SERS enhancement factor is increased by one order of magnitude achieving 1.6x108. Furthermore, the nanolaminated plasmonic structures have been integrated with micro-scale pillar arrays to control the surface wettability for ultrasensitive SERS measurements.

Dopamine and serotonin are two neurotransmitters known to both play a very important role in the human brain. For example, the death of dopamine producing neurons in a region of the brain known as the substantia nigra are known to cause the motor symptoms of Parkinson's disease. Also, many antidepressants are believed to work by increasing the extracellular level of serotonin in the brain. For the first time, it is now possible to measure the release of these two chemicals at sub-second time resolution in a human brain using a technique known as fast-scan cyclic voltammetry, for example from patients undergoing deep brain stimulation (DBS) electrode implantation surgery. In this work, we aimed to assess the feasibility of obtaining veridical dual measurements of serotonin and dopamine from substrates with mixtures of both chemicals. In the wet lab, data was collected on known concentrations of dopamine and serotonin and then used to make models capable of estimating the concentration of both chemicals from the voltammograms recorded in the patients. A method of linear regression known as the elastic net was used to make models from the wet lab data. The wetlab data was used to compare the performance of univariate and multivariate type models over various concentration ranges from 0-8000nM of dopamine and serotonin. Cross validation revealed that the multivariate model outperformed the univariate model both in terms of the linear correlation between predictions and actual values, and pH induced noise. The pH induced noise for the univariate model was 3.4 times greater for dopamine and 4.1 times greater for serotonin than the multivariate model. Raman spectroscopy was also investigated as a possible alternative to fast-scan cyclic voltammetry. Raman spectroscopy could have several benefits over fast-scan cyclic voltammetry, including the ability to chronically implant the measurement probe into a patient's brain and make observations over a long period of time. Raman spectroscopy data was collected on known concentrations of dopamine to investigate its potential in making in vivo measurements, however this data collection failed. Therefore, simulations were made which revealed the potential of the elastic net algorithm to determine the Raman spectra of several neurotransmitters simultaneously, even when they are in mixtures and the spectra are obstructed by the noisy background. The multivariate type model outperformed the univariate type model on Raman spectroscopy data and was able to predict dopamine with an error of 805nM RMS and serotonin with an error of 475nM RMS after being trained on concentrations smaller than 5uM of both dopamine and serotonin. In addition, the original Raman spectra of both neurotransmitters was extracted from the noise and reproduced very accurately by this method. / Master of Science

H2O and CO2 concentrations of the glass phase in melt inclusions (MI) are commonly used both as a barometer and to track magma degassing behavior during ascent due to the strong pressure dependence of H2O and CO2 solubilities in silicate melts. A requirement for this method to be valid is that the glass phase in the MI must represent the composition of the melt that was originally trapped. However, melt inclusions commonly contain a vapor bubble that formed after trapping. Such bubbles may contain CO2 that was originally dissolved in the melt. In this study, we determined the contribution of CO2 in the vapor bubble to the overall CO2 content of MI based on quantitative Raman analysis of the vapor bubbles in MI from the 1959 Kilauea Iki, 1960 Kapoho, 1974 Fuego volcano, and 1977 Seguam Island eruptions. The bubbles contain up to 90% or more of the total CO2 in some MI. Reconstructing the original CO2 content by adding the CO2 in the bubble back into the melt results in an increase in CO2 concentration by as much an order of magnitude (1000s of ppm), corresponding to trapping pressures that are significantly greater (by 1 to >3 kbars) than one would predict based on analysis of the volatiles in the glass alone. Many MI also showed the presence of a carbonate mineral phase; failure to include its contained CO2 when reconstructing the CO2 content of the originally trapped melt may introduce significant errors in the calculated volatile budget. / Master of Science

Fluids are associated with a wide range of physical and chemical processes in the Earth, including transporting and concentrating important ore elements such as Cu, Au, Zn, and Pb. Significant amounts of fluid may be generated as a result of dehydration or decarbonation reactions, and the volatile content of a magma is directly linked to the explosivity of eruptions. In most cases, small amounts of the fluids involved in the formation or alteration of rocks are trapped within minerals in the form of fluid inclusions. These fluid inclusions may be studied to understand the composition and pressure and temperature of the original fluid involved in the geologic process of interest, however, an understanding of the composition of the fluid as well as how the fluid behaves under changing pressure and temperature conditions is essential to reconstruct the fluid evolution path based on data obtained from fluid inclusions. Several analytical techniques are involved in the study of fluids, including fluid inclusion microthermometry and Raman spectroscopy. Microthermometry is the heating/cooling of fluid inclusions to observe and record temperatures of phase changes which, in turn, are used to determine properties such as salinity (based on the freezing point depression of liquid), or density based on the temperature at which all phases within the fluid inclusion homogenize to a single phase. Raman spectroscopy is a non-destructive analytical technique that measures the vibrational frequency of molecules in a given material. The Raman spectral properties of fluids act as a "fingerprint" of the chemical species within the fluid and serve to identify both the presence of chemical species, such as H2O, N2, CO2, and CH4, and the density of the fluid. Microthermometric and Raman spectroscopic experiments involving synthetic fluid systems are necessary to elucidate the pressure-volume-temperature-composition (PVTX) and Raman spectral behavior of the fluid systems, which then aids in the study and characterization of natural fluids. In chapter 1, the partitioning of NaCl and KCl between coexisting immiscible fluid phases during boiling is experimentally determined at temperatures and pressures relevant to magmatic-hydrothermal systems using synthetic fluid inclusions. The partitioning behavior is then combined with literature data to calculate the Na/K ratio of the original silicate melt phase in a magma body before the exsolution of a fluid phase. In chapter 2, we explore the Raman spectral behavior of N2, CO2, and CH4 in pure, single-component systems from PT conditions corresponding to the liquid-vapor curve to elevated temperatures and pressures, and relate the changes in the spectral behavior to changes in the bonding environment of the molecules through intermolecular attraction and repulsion. In chapter 3, the observations and relationships determined for pure fluids and described in chapter 2 are used to explore the Raman spectral properties of N2, CO2, and CH4 in the N2-CO2-CH4 ternary system and the manner in which the spectral behavior of each component in the system varies with changing temperature, pressure, molar volume, and fugacity. / Doctor of Philosophy / Water and other fluids play an important role in the formation of mineral deposits that are the source of the many metals, such as copper, silver, gold, and others, that are needed by a modern technological society. In addition, water and other fluids affect the way rocks behave under stress and can promote earthquakes and influence the explosivity of volcanoes. When minerals in a rock form, often small amounts of the fluid will be trapped within the minerals in the form of fluid inclusions. These fluid inclusions contain samples of the fluid involved in the geologic process of interest and can be studied using a variety of methods to determine the chemistry and the temperature and pressure conditions of rock formation. Two of the many methods used to study fluid inclusions are microthermometry and Raman spectroscopy. Microthermometry involves heating and/or cooling the fluid inclusion while it is being observed on a microscope, and this method can be used to determine the salinity of water in the inclusion and the fluid density. The density of the fluid may then be used to determine the pressure or temperature at which the fluid was encapsulated into the rock, and by extension the temperature and pressure at which the rock formed. Raman spectroscopy is an analytical technique in which a rock or fluid is illuminated using a laser. The laser light interacts with the rock or fluid and gains or loses energy, and this change in energy serves as a "fingerprint" to identify the molecules in the rock or fluid. The Raman spectrum can also be used to determine fluid density because the signal generated when the laser interacts with the fluid depends on the density of the fluid. Experiments on fluids at carefully-controlled laboratory conditions are necessary to understand the behavior of fluids trapped in natural samples. In chapter 1, the preference of sodium and potassium to go into either a liquid or a gas phase during boiling at high pressures and temperatures is determined. In chapter 2, gases containing only nitrogen, carbon dioxide, or methane are studied using Raman spectroscopy and the changes in the Raman behavior of the gases with changing pressure and temperature are related to molecular interactions. In chapter 3, the results from chapter 2 are used to understand the Raman behavior of nitrogen, carbon dioxide, and methane in gas mixtures as pressure and temperature are changed and how this relates to the interactions of the molecules.

Raman and/or infrared (IR) bandshape analysis to probe molecular dynamics in liquids has become a rapidly expanding field of study in recent years. Determination of spinning and tumbling diffusion constants, Dι and D⊥, which characterize the reorientation of symmetric-top moleclues has been successfully studied in a number of D6H and D3H molecules. For molecules of CV3 symmetry, however, previous attempts to extract spinning diffusion constants from Raman doubly degenerate vibrations (E mode) have proved unsuccessful. Presented here is a new methodology which resolves the problems encountered by former researchers through calculation of Dι utilizing the narrower Lorentzian component of E vibrations.

No / This paper reviews the contributions of analytical Raman spectroscopy to the non-destructive characterisation of biological materials of relevance to forensic science investigations, including the sourcing of resins and the identification of the biodegradation of art and archaeological artefacts. The advantages of Raman spectroscopy for non-destructive analysis are well-appreciated; however, the ability to record molecular information about organic and inorganic species present in a heterogeneous specimen at the same time, the insensitivity of the Raman scattering process to water and hydroxyl groups, which removes the necessity for sample desiccation, and the ease of illumination for samples of very small and very large sizes and unusual shapes are also apparent. Several examples are used to illustrate the application of Raman spectroscopic techniques to the characterisation of forensic biomaterials and for the preservation of cultural heritage through case studies in the following areas: wall-paintings and rock art, human and animal tissues and skeletal remains, fabrics, resins and ivories.

No / The Raman and mass spectra of 1,4-diphenylbuta-1,3-diene and several of its monomethyl and dimethyl homologues are reported and discussed, with a view to developing a spectroscopic protocol for detecting the presence and position of a methyl group in these compounds. Raman spectroscopy and mass spectrometry are shown to provide complementary information, by which the four available monomethyl homologues may be readily distinguished from each other and 1,4-diphenylbuta-1,3-diene itself. The utility of these 1,4-diarylbutadienes as model compounds for carotenoids and related materials, which may serve as indicators of extinct or extant extraterrestrial life, is considered.

No / The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.