In this dissertation, I provide a thorough description of my development of theoretical, analytical, and experimental techniques pertaining to novel measurements of the electrostatic double layer (EDL) using atomic force microscopy (AFM), among other techniques. The EDL is an important physical element of many systems and its behavior has been of interest to scientists for many decades. Because many areas of science and engineering are moving to test, build, and understand systems at smaller and smaller scales, this work focuses on nanoscopic experimental investigations of the EDL. In that vein, AFM will be introduced and discussed as a tool for making high spatial resolution measurements of the solid-liquid interface, culminating in a description of the development of a method for completely characterizing the EDL using direct force measurements with AFM.

I first explore, in a historical fashion, the development of the various models and theories that are used to describe the electrostatic double layer. Later, various experimental techniques and ideas are addressed as ways to make measurements of interesting characteristics of the EDL. Finally, I will introduce a newly developed approach to measuring the EDL system with AFM. This approach relies on both the implementation of existing theoretical models with modifications as well as a unique experimental measurement scheme. The model proposed clarifies previous ambiguities in definitions of various parameters pertaining to measurements of the EDL and also can be used to fully characterize the system in a way not yet demonstrated. Specifically, I show that AFM can be used to measure the two most commonly referenced potential drops in a solid-liquid interface system, referred to as the diffuse layer potential and the Stern potential. Also, in concert with the aforementioned model, the potential of the solution itself with respect to an external measurement point can be calculated. Experimental data validates the implementation of such a model and, together, the results indicate that AFM can be used to fully characterize the electrostatic environment of certain solid-liquid interface systems.