The promise of optical antennas is the ability to tame the light to behave in ways not achievable using traditional optical components. For example, our results here demonstrate that a careful engineering of optical antennas allow the strong, even perfect, absorption of light in ultra-thin geometries, i.e., geometries much thinner than the wavelength of light. Enabled by geometry-sensitive antenna resonances, this absorption behavior can also be realized for a broad selection of colors. A detailed theoretical analysis of the observed perfect absorption phenomenon reveals the role of incoherently interacting degenerate electric and magnetic resonances in overcoming the well-known absorption limit for infinitesimally thin films. With another set of experiments, we show that strongly absorbed optical energy in aluminum nanoantennas can be used to heat them efficiently above their melting temperature and stimulate an explosive exothermic oxidation reaction called melt-dispersion mechanism. Importantly, we see that engineering the specific geometry of the constituent particles allows an unprecedented control of aluminum ignition, both spectrally and spatially, through the fine tuning of the optical antenna resonances.

The playwright Eugene O'Neill (1888-1953) produced a body of work—thirty-one full-length plays, and twenty-one one-act plays—that was ambitious in its stylistic innovations, and daring in its thematic concerns. As recounted by historians, biographers, and critics, O'Neill's private life informed his writing process, with his various ailments serving as prompts for the stage. Whenever the theme of addiction appears, as it does in his final plays The Iceman Cometh (1939), Long Day's Journey Into Night (1941), and A Moon for the Misbegotten (1943), scholars note the autobiographical aspect as generative for his artistic output. Painted as a depressive figure whose dysfunctional upbringing made a lifelong impression on him, current literature on O'Neill celebrates the playwright for his distinctly sincere expression of suffering and strife. O'Neill wrote his final plays during a period of renewed interest in addiction science in the nation following World War II. After the failed enterprise of Prohibition, scientists, politicians, and the public instated a new treatment paradigm that placed responsibility on the individual who drinks problematically. This approach helped solidify addiction as a biological—rather than a social or cultural—phenomenon. As a result, the disease model of addiction offered an identity that was receptive to addiction treatment. While the previous century saw the construction of the addict as a person with a weak will, the disease model of addiction constituted the addict's condition as an illness treatable through performative acts. O'Neill's final plays, then, reflect more than the playwright's direct experience with addiction. They reveal the nation's ambivalence towards the concept of addiction as a disease, and with the addict as a sick person. Spectators in post-WWII America labeled O'Neill's final plays as autobiographical not only because he drew from his personal experiences while writing them, but also because such an approach was seen as critical to the addict's recovery. As a result, theater scholars continue to position O'Neill as an artist who utilized the theatre as a transformative tool to address how addiction impacted his own life. Through his compassionate depictions of characters suffering from a disease, O'Neill's late plays showed how recovery depended upon theatrical acts of self-reflection, self-narrative, and self-actualization. They also reflect how spectators saw autobiography as the discursive mode for recovering from addiction. In this sense, I claim that it was not so much that O'Neill's plays were true to life and accepted as such, but that their content on addiction necessitated a search for disclosure in the first place. Rather than explore how the theatre allowed O'Neill to channel his suffering, I instead consider why live performance serves as a durable site for legitimating addiction as an illness. As O'Neill's late plays show, self-disclosure does not lead to an emancipatory experience devoid of coercion. Despite claims made by the medical field and mutual aid groups of its liberatory potential, these acts of recovery encourage self-governance, and trade on the morally inflected narratives about the addict circulating since the nineteenth century. As the first study to consider the collaborative relationship between Eugene O'Neill and the medical field, I consider how the playwright's representation of addicts directly influenced doctors and scientists who engaged with his work from 1939 until the present.

Our climate is changing. Although the extent and rate of change are still uncertain, it is abundantly clear that the climate of the future will not resemble the climate of the past and will pose significant risks to people around the world. How well people adapt to address these risks will be determined by their adaptive capacity, their ability to instigate and implement change. Understanding and building adaptive capacity may therefore be key to reducing long-term vulnerability to global change. This dissertation clarifies the concept of adaptive capacity, synthesizes the substantial but largely unconnected body of research on adaptive capacity to date, and introduces a new methodological approach to conducting meta-analyses of adaptation science. I express a definition of adaptive capacity in mathematical terms that summarizes current theories on how adaptability is built, ties the concept to related concepts in adaptation, and poses questions about theoretical limits and thresholds for adaptation. I apply computational text analysis and network analysis tools to develop a concept model of adaptive capacity that identifies and organizes 158 determinants of adaptive capacity into 8 categories according to the functional role they play in building capacity. I propose a modular theory of adaptive capacity, in which all eight functional categories are critical but multiple pathways exist to achieve each function. This modular theory reconciles a theoretical debate in the literature and connects insights from existing theories with empirical findings from the field. I propose a new framework, the Adaptive Capacities Framework (ACF), based on the eight functional categories, that enables assessment of adaptive capacity across scales and within multi-scalar systems. Results demonstrate the fragmented nature of adaptive capacity research to date and propose new directions for future research. The dissertation also provides insights for practitioners seeking to prioritize adaptation efforts.

The technological revolution that started with digital electronics more than 50 years ago has pushed the limits of scalability in device fabrication. Device features are currently at the nanometer scale, which requires structures to be built with atomic level accuracy. Advances in nanotechnology have opened up an exciting area of research that allows for molecular level control of device surfaces. Organic molecules can provide the tailorability required to continue the progress of semiconductor technologies. Organic functionalization provides a pathway to control the surface at the molecular level. Fundamental understanding of the adsorption phenomena between organic molecules and the surface is critical to achieve a stable inorganic/organic interface for the creation of hybrid nanostructures. This thesis aims to expand our current toolkit on functionalization to molecules that have multiple functionalities that can react with the surface. The reaction mechanism of these molecules is complex as there are several driving forces that can play a role during adsorption and influence the final reaction products. This thesis covers the adsorption of multifunctional molecules on the Ge(100)-2×1 surface using a combination of experimental and theoretical techniques: Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. We explored the adsorption of four different molecules: 1,2,3-benzenetriol (C6H6O3); 1,3,5-benzenetriol (C6H6O3); 2-hydroxymethyl-1,3-propanediol (C4H10O3); pyrazine (C4H6N2). These are the first reported studies of these molecules on the Ge(100) surface. In order to understand the extent to which molecular geometry affects surface coverage, a detailed comparison of the adsorption of two triol molecules was carried out: 1,3,5-benzenetriol which has a rigid phenyl backbone and 2-hydroxymethyl-1,3-propanediol with a flexible alkyl backbone. DFT results showed that the rigid backbone exhibits a higher degree of strain, which translates to a loss of exothermicity in the reaction coordinate. Experiments showed that the flexibility of the alkyl backbone provides higher rotational degrees of freedom and an enhancement in surface coverage. In order to understand the effect of intermolecular interactions, the adsorption of 1,2,3-benzenetriol was explored. Interestingly, we found that at high coverage, intramolecular hydrogen bonding in singly and dually adsorbate products breaks to form intermolecular hydrogen bonding with a nearby adsorbate, which provides enhanced stabilization of the surface adduct. This additional stabilization may lower the reactivity of unreacted functional groups even if an empty nearby Ge site is available for reaction. The distribution of products resulted in primarily bidentate adsorbates, leaving an unreacted moiety at the surface. We also found evidence of coverage and temperature effects on adsorbed pyrazine molecules on the Ge surface. It was observed that this molecule adsorbs on Ge through both carbon and nitrogen moieties and the product distribution changes as a function of coverage and temperature. At low coverage, incoming molecules react primarily through C-cycloaddition reactions and N dative bonds. However, as the density of adsorbates increases, new incoming molecules adsorbed primarily through the nitrogen moiety. Furthermore, as the temperature increases, the product distribution changed from primarily non-activated dative bond to activated cycloaddition products. Overall, the studies in this thesis provide new insight into competition and selectivity in adsorption of multifunctional molecules on the Ge(100)-2×1 surface.

Photochemistry studies chemical reactions caused by absorption of light. Developing theoretical and computational tools for photochemistry will not only help better understand photochemical processes such as photosynthesis and vision, but can also provide guidelines about how molecular photodevices can be better designed. Therefore, the goal of my graduate research is to develop a set of computational tools for studying photochemical processes. Physical systems have a hierarchical structure, i.e. basic particles like nuclei and electrons interact leading to the formation of molecules, and molecules interact and change conformations giving rise to chemical reactions. Naturally, the corresponding theoretical methods should also follow this hierarchy. At the bottom level, we need molecular integrals to describe different types of interactions between basic particles. I introduced the automated code engine (ACE) that generates optimized codes for computing integrals on the graphical processing units, and developed several variants of tensor hyper-contraction (THC) approximations. ACE reduces the computational prefactor of integral evaluations whereas THC reduces the formal scaling. On top of the integrals, we then need electronic structure methods to describe the energies and forces for a molecule at any given nuclear configuration; including electron correlation is the key to having an accurate description. Here, I first developed single reference THC-MP2 to capture the dynamic correlations, and then developed multi-reference THC-CASPT2 method to incorporate static correlations simultaneously. These methods were later generalized to THC-MSPT2 to enable descriptions for excited states and conical intersections, both are critical for photochemistry. Finally, given the electronic structure methods, we then need methods to explore the potential energy surfaces. In particular, critical point search methods locate the important configurations (e.g. Franck-Condon point, conical intersections), while molecular dynamics methods generate trajectories describing how the molecules move and interact with each other. By interfacing the electronic structure methods that I developed with the geomeTRIC geometry optimizer and G-AIMS non-adiabatic dynamics framework, a complete toolbox for understanding photochemistry is provided.

Silicon Photonics is considered to be essential for the sustained growth of semiconductor industry moving forward. The ubiquitous mobile devices and Internet of Things (IoT) are driving the data needs of the end user exponentially which has led to numerous data centers and perilously large power consumption in each of them. More than 3.4 billion people in the world have access to internet today and this number is increasing steadily day by day. Together, we generate more than 50 Terabytes (50,000 Gigabytes) of internet traffic per second at any given point of time. This number was just 100 Gigabytes per second in 2002 and it is expected to grow much faster going into the future. As for the power consumption, US data centers alone consumed about 70 billion kilowatt-hours of electricity in 2014, representing 2 percent of the country's total energy consumption, according to a study. That's equivalent to the amount consumed by about 6.4 million average American homes that year. This is a 4 percent increase in total data center energy consumption from 2010 to 2014, and a huge change from the preceding five years, during which total US data center energy consumption grew by 24 percent, and an even bigger change from the first half of last decade, when their energy consumption grew nearly 90 percent. It is well established that the copper cables which transfer data from one end of the data-center to the other are the bottlenecks reducing the overall bandwidth of the system and skyrocketing the power consumption on the whole. This bottleneck is getting worse day by day owing to the ever-increasing data needs. Silicon Photonics based 'optical interconnects' are the best solution to remove this bottleneck. Optical interconnects use photons instead of electrons for communication and therefore have the potential to offer very large bandwidths at minimal power consumption. In the very near future all the copper wires in the data-center ecosystem will have to be replaced by these optical interconnects if we must meet the data needs within the prescribed power budget. In order to build such a platform where conventional machines in the data center work in tandem with novel interconnects based on photon-devices, all the optical components need to be integrated seamlessly on a silicon chip. Modulators are the most important optical component of such a platform since they act as optical switches which control the flow of photons. In the first part of the dissertation, a silicon compatible germanium (Ge) electro-absorption modulator with the best reported energy-delay product is demonstrated. The figure-of-merits along with the design principles are discussed in detail while the fabrication methodology is briefly touched upon. Experimentally measured characteristics are then shown to be the best-in-class and ones that match the data requirements of the data-centers with minimal energy consumption. In the second part of the dissertation, we focus on developing an efficient silicon-compatible light emitter based on strained Ge technology. Detailed theoretical calculations lay down a roadmap for room-temperature lasing from Ge. These calculations also prove that the loss mechanisms involved in the light emission process from Ge have been inadequately modeled until now and shows that a particular loss mechanism known as the inter-valence-band absorption is a major barrier in the realization of a strained Ge laser. CMOS compatible fabrication techniques to introduce large uniaxial strain in Ge are then discussed. Finally, a low-threshold Ge laser at a temperature of 83 K is demonstrated. In the final part of the dissertation, the first demonstration of a 'truly' silicon compatible three-dimensional (3D) photonic crystals is discussed. Using the methodology developed, a broadband omnidirectional reflector is also demonstrated on silicon. This methodology is also shown to be particulary well suited for 3D waveguides and optical cavities.

Accurate observations and descriptions of the role of heterogeneity on water and CO2 transport and immobilization in porous and fractured geologic media are important for understanding and modeling multiphase conditions present in geologic carbon storage reservoirs. The growth in in-situ imaging has lead to remarkable advancements in understanding and quantification of this complex fluid transport behavior. Despite these advancements, commonly used imaging and experimental methods such as clinical computed tomography, micro computed tomography, nuclear magnetic resonance, and optical imaged micromodels each have limitations. Each modality faces individual challenges with observing fluid advection, dispersion, and diffusion, in 3D geologic porous media. In this work, micro-positron emission tomography (micro-PET), in combination with other imaging methods, is utilized to study a number of challenging transport problems in earth science.