Preparation and characterization of nanoporous gold thin films

In the first chapter, methods for preparing different types of nanoporous Au (nPG) are described, along with a wide variety of applications and uses in the scientific and engineering community. Of particular interest, though, is the nanoporous structure that arises from dealloying Ag from AgAu. Details about the formation of AgAu alloys and the different methods for dealloying AgAu alloys are discussed, including a brief history of the dealloying mechanism for a binary alloy. The chapter concludes with a brief overview of the thesis' subsequent chapters.; The second chapter focuses on the preparation and characterization of nPG thin films of varying thickness and etch times. We adapted the approach of dealloying Ag from AgAu due to its widespread application, well understood mechanism, uniformity in pore size, and reproducible structure formation. The atomic percentage of Ag70Au30 was chosen for this work since an initial collaboration and previous studies have used this particular ratio, and demonstrated pore sizes on the order of tens of nanometers were achievable upon dealloying. We designed a new technique to deposit AgAu alloys onto surfaces. Specifically, the technique entailed argon ion sputtering a premade ingot containing Ag70Au30 onto a substrate.; The third chapter describes the functionaliztion and subsequent characterization of organic films chemisorbed onto a variety of nPG films. Self-assembled monolayers of thiol containing molecules were made using typical literature procedures. The coverage of a variety of molecules were estimated using depth profiling XPS, solid state nuclear magnetic resonance, adsorption measurements and redox electrochemistry. Film quality was estimated using electrochemical tunneling measurements and reflection infrared spectroscopy; these showed that film quality on nPG was comparable to that on flat Au. The macroscopic wetting properties of functionalized nPG, as measured using contact angles, were found to reflect the morphology of the underlying substrate, while the microscopic wetting of functionalized nPG, as measured by water vapor adsorption, inhibited the adsorption of water vapor.; Chapter 4 applies the nPG films to Surface Enhance Raman Spectroscopy (SERS), in the context of developing reproducible and uniform high-intensity substrates. The SERS response of a variety of nPG films prepared under different conditions were measured with various thiol molecules. Optimum substrate conditions were found for the highest SERS intensity for both untreated nPG and electrochemically roughened nPG. Enhancement factors of the nPG substrates were measured to be on the order of 104-105. (Abstract shortened by UMI.)...