We report experimental results of the adsorption and desorption kinetics of 1-octadecanethiol onto porous gold quartz crystal microbalances (QCM). Fabricated porous gold substrates range in thickness from 75 nm to 3 µm. The porous gold was fabricated using a two-step process of sputtering and etching. First, an alloy of gold and silver was sputtered onto a flat gold QCM with the desired ratio of roughly 70 atomic percent silver and 30 atomic percent gold. Second, the sputtered silver from the alloy was removed by etching in concentrated nitric acid, leaving a gold nanoporous structure on the surface. This porous gold structure on the QCM surface greatly increases the surface area of the sensor, allowing much more thiol to be adsorbed.

Experimental adsorption kinetics are compared to a Langmuir isotherm model. Thiol adsorption on porous QCM in n-Hexane is presented with concentrations ranging from 10nM (5ppb) to 3mM (900ppm). Thiol adsorption and kinetics on a nominally flat gold surface are included for comparison. Optimized sputtering conditions for porous gold substrates lead to a 1000-fold increase of thiol adsorption over flat gold QCM. It follows that the high specific area of porous gold can amplify the final sensitivity of a flat QCM by more than 3 orders of magnitude. We further present evidence that the three orders of magnitude sensitivity increase we achieve is the maximum enhancement possible when used in liquids for thiol detection. We verify our theoretical model of the QCM, describe our fabrication technique, characterize our substrates, and detail the uses of our porous gold QCM.

The Mu to E Gamma (MEG) II experiment is designed to increase the sensitivity of the original MEG experiment by an order of magnitude in the search of the μ+ Þ e+ g decay that violates lepton flavor conservation, which is not allowed [1]. The final results of the original MEG experiment at the Paul Scherrer Institut (PSI) during the period of 2009-2013 produced 7.5 x 10^14 muons stopped on target, and put a new upper limit on the branching ratio of this decay of b(μ+ Þ e+ g) < 4.2x10^-13 [2]. The MEG II upgrade features the world’s most intense DC muon beam, innovative liquid xenon tank (LXe) g-ray detectors, and many sophisticated calibration methods [3,4]. One vital method being implemented to calibrate the 4092 scintillation detectors inside the LXe is the use of our novel X-ray beam. Two additional methods have been introduced to crosscheck the alignment of the LXe detectors. In this thesis we present an overview of the MEG II experiment, the constraints on our alignment device, the design, alignment procedure, and results of this new calibration device.