Solar-induced chlorophyll fluorescence (SIF) has been widely cited in carbon cycling studies as a proxy for photosynthesis, and SIF data are commonly incorporated into terrestrial primary productivity models. Though satellite-based SIF products show close relationships with gross primary productivity (GPP), this is not universally true at intermediate scales. A meta-analysis of the tower-based and airborne SIF literature revealed that mean SIF retrievals from unstressed vegetation span three orders of magnitude. While reporting on spectrometer calibration procedures, hardware characterizations, and associated corrections is inconsistent, laboratory and field experiments show that these factors may contribute to significant uncertainty in SIF retrievals. Additionally, there remain ongoing questions regarding the interpretation of SIF data made across spatial scales and the link between satellite SIF retrievals and primary productivity on the ground. Chlorophyll fluorescence originates from dynamic energy partitioning at the leaf level and does not exhibit a uniformly linear relationship with photosynthesis at finer scales. As a standalone metric, SIF measured at the tower scale was not found to track changes in carbon assimilation following stomatal closure induced in deciduous woody tree branches. This lack of relationship may be explained by alternative energy partitioning pathways, such as thermal energy dissipation mediated by xanthophyll cycle pigments; the activity of these pigments can be tracked using the photochemical reflectance index (PRI). Gradual, phenological changes in energy partitioning are observed as changes in the slope of the SIF-PRI relationship over the course of a season. Along with high frequency effects such as wind-mediated changes in leaf orientation and reflectance, and rapid changes in sky condition due to clouds, PRI offers crucial insights needed to link SIF to leaf physiology. While SIF offers tremendous promise for improving the characterization of terrestrial carbon exchange, and a fuller understanding of the boundaries on its utility and interpretation as a biophysical phenomenon will help to create more reliable models of global productivity.

My dissertation focuses on (i) the development sputtered films for solid phase microextraction (SPME) and (ii) the comprehensive characterization of materials using a suite of analytical techniques. Chapter 1 reviews the basics of SPME. This chapter also contains (i) a discussion of various sputtering techniques, (ii) a discussion of two techniques I focused on most of my work: spectroscopic ellipsometry (SE) and X-ray photoelectron spectroscopy (XPS). Chapter 2 focuses the major part of my work, which is to prepare new solid phases/adsorbents for SPME via silicon sputtering followed by thermal deposition of a polymer, polydimethylsiloxane (PDMS). PDMS was deposited by a simple gas phase technique which has never before been applied to prepare SPME stationary phases. The coatings were characterized by time-of-flight mass spectrometry (ToF-SIMS), XPS, scanning electron microscopy (SEM), SE, and contact angle goniometry. The extraction efficiencies of ca. 1.8 µm sputtered, PDMS-coated fibers were compared to a commercial fiber (7 µm PDMS) for a series of polycyclic hydrocarbons (PAHs). Large carry-over and phase bleed peaks are observed in case of commercial PDMS-based SPME coatings, which decrease the lifetime and usefulness of these fibers. It is of great significance that our sputtered fibers exhibit very small or negligible carry-over peaks and phase bleed peaks under the same conditions. Chapter 3 focuses on the multi-instrument characterization of copper and tungsten films sputtered by direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) using a modern sputter source. The resulting films were characterized by energy dispersive X-ray spectroscopy (EDX), XPS, SEM, atomic force microscopy (AFM), SE, and X-ray diffraction (XRD). By EDX and XPS, all the sputtered films only showed the expected metal peaks. By XPS, the surfaces sputtered by DCMS were richer in oxygen than those produced by HiPIMS. By AFM, both surfaces were quite smooth. By SEM, the HiPIMS films exhibited smaller grain sizes, which was further confirmed by XRD. The crystallite sizes estimated by XRD are as follows: 18.2 nm (W, HiPIMS), 27.3 nm (W, DCMS), 40.2 nm (Cu, HiPIMS), and 58.9 nm (Cu, DCMS). By SE, the HiPIMS surfaces showed higher refractive indices, which suggested that they were denser and less oxidized than the DCMS surfaces. Chapter 4 reports characterization of liquid PDMS via SE, which required some experimental adaptations. The transmission measurements were obtained via a dual cuvette approach that eliminated the effects of the cuvettes and their interfaces. Only the reflection measurements were modeled with a Sellmeier function which produced decent fits. Chapters 5 consists of contributions to Surface Science Spectra (SSS) of near-ambient XPS spectra of various unconventional materials including cheese, kidney stone, sesame seeds, clamshell, and calcite. This dissertation also contains appendices of tutorial articles I wrote on ellipsometry and vacuum equipment.

The BRIght Target Explorer (BRITE) constellation is revolutionary in the sense that the same scientific objectives can be achieved smaller (cm3 versus m3 ) and lighter (< 10kg versus 1, 000kg). It is a space astronomy mission, observing the variations in the apparent brightness of stars. The work presented herein focuses on the assembly, integration and test of the instrument used on-board six nanosatellites that form the constellation. The instrument is composed of an optical telescope equipped with a Charge Coupled Device (CCD) imager and a dedicated computer. This thesis provides a particular in-depth look into the inner workings of CCD. Methods used to characterize the instrument CCD in terms of its bias level stability, gain factor determination, saturation, dark current and readout noise level evaluation are provided. These methodologies are not limited to CCDs and they provide the basis for anyone who wishes to characterize any type of imager for scientic applications.

The BRIght Target Explorer (BRITE) constellation is revolutionary in the sense that the same scientific objectives can be achieved smaller (cm3 versus m3 ) and lighter (< 10kg versus 1, 000kg). It is a space astronomy mission, observing the variations in the apparent brightness of stars. The work presented herein focuses on the assembly, integration and test of the instrument used on-board six nanosatellites that form the constellation. The instrument is composed of an optical telescope equipped with a Charge Coupled Device (CCD) imager and a dedicated computer. This thesis provides a particular in-depth look into the inner workings of CCD. Methods used to characterize the instrument CCD in terms of its bias level stability, gain factor determination, saturation, dark current and readout noise level evaluation are provided. These methodologies are not limited to CCDs and they provide the basis for anyone who wishes to characterize any type of imager for scientic applications.