With this award from the Major Research Instrumentation (MRI) Program, Professor Jennifer Hampton from Hope College and colleague Mary Anderson will acquire an atomic force microscope. The award will enhance research training and education at all levels, especially in areas such as (a) exploration of underlying physical and chemical forces directing the assembly of asymmetrically-shaped particles, (b) study of the morphology and surface functionalization of intermetallic thin films and particles fabricated by solution-phase solid-state chemistry methods, and (c) investigation of controlled nucleation and crystal growth based on underlying thin organic films that are assembled on curved surfaces and within constrained geometries.
An atomic force microscope is used to characterize surface topography on a nanoscale level, distinguish different molecular coverage on surfaces, unfold polymers, calculate substrate stiffness, and quantify interaction forces. The AFM generally has a cantilever with a sharp point at its end used to scan the specimen surface. When the tip is brought into proximity of a sample surface, forces between the tip and the sample lead to a deflection of the cantilever. This deflection is often measured using a laser spot reflected from the top surface of the cantilever into a detector. This instrument will be used not only in research but also for research training of students and for outreach activities.
This project enabled the purchase and installation of a Bruker Dimension Icon Atomic Force Microscope (AFM) at Hope College in the fall of 2011. The AFM is the highest resolution instrument for imaging on campus, allowing a variety of new avenues of research. It is a key component in the suite of instrumentation which constitutes the Hope College Materials Characterization Laboratory housed in VanderWerf Hall. Intellectual Merit As the result of the AFM purchase, an array of material systems has been studied in the three years of this award. Research has been conducted across many departments on campus, including Physics, Chemistry, and Biology. Research collaborations have been initiated which involved the Senior Personnel on the proposal as well as new individuals. The types of samples investigated to date (represented in the accompanying images) range from metal alloys (Electrodeposited NiFe Film), metal-organic coordinated systems (Surface-anchored Metal-Organic Frameworks), electropolymerized organic films (Electrodeposited Polymer Film), to biological systems (Glioblastoma Cell). Research highlights include: Electrochemical double-layer capacitance measurements of electrodeposited metal and alloy thin films are correlated with the roughness factors calculated from AFM topography. These correlations provide a straight-forward in situ estimate of accessible surface area for comparing sample reactivity. (Hampton, PI) AFM image analysis revealed and quantified significant structural transitions through the early stages of metal-organic coordinated multilayer film growth, with a stable structure resulting after five layers of deposition. These multilayers serve as a model system for the emerging field of metal-organic coordinated frameworks. (Anderson, co-PI) The AFM characterization of a commonly-studied surface-anchored metal-organic framework system has shown that the often accepted conformal structure resulting from the layer-by-layer deposition is not valid for the formation of the foundational layers of the film. This type of fundamental understanding is vital for those researchers who would desire to incorporate the film into a device structure. (Anderson, co-PI) Electropolymerized thin films were fabricated on indium tin oxide surfaces, and AFM was used to investigate the film thickness and morphology. These films are being optimized for sensing applications (Sanford and Brown, Senior Personnel). Additional collaborations with Senior Personnel and other groups include characterization of biological systems, patterned superconducting films, and ferroelectric thin films. Broader Impacts Fourteen students have been trained in the use of the instrument (Students During Installation and Training), and many more students have had supervised single-use periods. Students have been exposed to atomic force microscopy as a research tool through course work, outreach activities, and admissions visit programs. During the period of the award, 37 internal and 28 external or invited presentations including data taken with the instrument were given. To date, the research enabled by the AFM has resulted in 4 manuscripts which are in various stages of the submission process.
