LAUSR

Nonlinear optics and aligned water reveal the chemical heterogeneity of surfaces Surface chemical heterogeneity critically affects nearly all interfacial processes and is particularly relevant in surface chemical reactions in catalysis, charge transfer in nanostructured materials, and biomineralization. The general goal, with respect to surface heterogeneity, is to characterize surface heterogeneities in space and time and, eventually, manipulate them in order to relate them with macroscopic observables, such as catalytic conversion or mineral dissolution. Direct characterization of surface heterogeneity is difficult, especially in a spatially resolved measurement, and often requires techniques such as ultrahigh vacuum atomic force microscopy or electronic spectroscopy setups that place the sample in unnatural environments. On page 784 of this issue, Macias-Romero et al. (1) present a microscope capable of imaging surface heterogeneity in situ with unprecedented speed and spatial resolution, without any labels. The microscope is used to image surface potential (charge)/acidity heterogeneities of silica surfaces.