Trends in high spatial high spectral resolution material characterization A. Passian, L. Tetard, R. Farahi, B. Davison, A. Lereu, T. Thundat, S. Gleason, K. Tobin Measurement Science and Systems Engineering Division (MSSE) Oak Ridge National Laboratory, Oak Ridge, TN USA passianan@ornl.gov Morphological and spectral properties of surfaces and interfaces are often closely related at small spatial scales. In the case of nanomaterials, such as those currently used in medicine, electronics, aeronautics, automotives, and energy an understanding of the physical properties is required often at the scale of these novel materials. These circumstances have driven the development of new analytical tools. Given the very small dimensions, concentrations, quantities, densities etc., a key challenge is the quantitative characterization of these engineered or natural, chemical or biological materials within the composite material or biological system. Two fundamental properties of interest – location and identification – demand high spatial resolution (both surface and subsurface) and chemical speciation. While high resolution may benefit from scanning probe microscopy technologies, chemical speciation may be realized through spectroscopy. In this paper we discuss some potential approaches to achieving high spatial and high spectral material characterization. State-of-the-art near-field and remote-standoff instrumentation for diverse applications in biofuel production, nanotoxicology, plasmon nano-devices, food quality control, and chemical threat agent detection are discussed. Keywords-microscopy, spectroscopy, subsurface, standoff, nanomaterial, nanotoxicology, biofuel, atomic force microscopy, near-field scanning optical microscopy I. INTRODUCTION Undoubtedly, modern measurement technologies and tools are heavily impacted by a need to provide an understanding of material properties at scales relevant to the development of applications that can uniquely use specific properties to achieve a function or perform a task. Visual inspection has always been an important first approach to understanding materials. However, historically understanding the atomic fabric of materials was not instrumental for the evolution of our species rendering our eyesight limited to about 0.35 mm. As a result, optical microscopy broke this first visual barrier, only to be declared limited by the diffraction to half of the wavelength of the light as stated by Abbe [1]. Many attempts have been since made to break Abbe’s barrier resulting in Scanning Tunneling Microscopy, Scanning Electron Microscopy, Transmission Electron Microscopy, Photon Scanning Tunneling Microscopy, Near-Field Scanning Optical Microscopy (NSOM), Atomic Force Microscopy (AFM), going beyond the diffraction limit. Probe based microscopy further offered the potential advantage of nondestructive approaches where the sample is not disturbed. However, three immediate challenges continue to resurface in many applications: 1) acquiring sample chemical information, 2) lack of physical access to the sample, and 3) acquiring sample subsurface information. This paper addresses how some potential approaches can overcome these challenges. Section II describes hyperspectral mode synthesizing atomic force microscopy (hMSAFM) for nanoscale point contact characterization. In doing so, we first describe our imaging methodologies and their potential applications in biofuel energy research and nanotoxicology. Imaging providing physical and mechanical properties such as morphology and elastic response of the materials is augmented with novel spectroscopic approaches to provide chemical information. Many future devices will require a suite of integrated tools, such as lab-on-a chip. In Section III, we therefore describe how plasmonics may aid the creation of such integrated tools. In cases where physical contact with the sample is not an option, reliable tools are needed to obtain information remotely. Such processes may provide information ranging from simple false/positive detection of a given known species to a more complex chemical and spectral recognition and identification of remote object surface and subsurface properties. In Section IV, we discuss remote hyperspectral imaging (RHI) for standoff spectral investigations. Here we discuss potential applications in quality control and detection of chemical and biological threat agents as examples. Finally, concluding remarks are provided in Section V. II. MODE SYNTHESIZING ATOMIC FORCE MICROSCOPY The ability to noninvasively explore subsurface and surface composition and inhomogeneities in a given sample constitutes a major challenge in material characterization. Understanding the composition and behavior of complex systems requires access to physical, structural and chemical information with high spatial resolution. The AFM provides a powerful approach to noninvasive nanoscale characterization. AFM imaging is based on the scanning of a sharp tip (tens of nanometers in diameter) located at the end of a micro- cantilever probe, over the surface of the sample. The tip- sample interaction and the consequent changes in the probe’s elastic state are monitored by a sensitive read-out technique. The resulting signal is then converted into a contrast map or an