Progress in nanotechnology is enabled by and dependent on the availability of measurement methods with spatial resolution commensurate with nanomaterials length scales. Chemical imaging techniques, such as scattering scanning near-field optical microscopy (s-SNOM) and photothermal induced resonance (PTIR), has provided scientists with means of extracting rich chemical and structural information with from nanoscale resolution. This review presents some basics of infrared spectroscopy and microscopy, followed by detailed descriptions of s-SNOM and PTIR working principles. Nanoscale spectra will be compared with far-field macroscale spectra, widely used for chemical identification. Selected examples will illustrate either technical aspects of the measurements, or applications in materials science. Central to this review is the ability to record nanoscale infrared spectra because, although chemical maps enable immediate visualization the spectra provide information to interpret the images and characterize the sample. The growing breadth of nanomaterials and biological applications suggest a rapid growth for this field.
Annual Review of Analytical Chemistry
s-SNOM, PTIR, REINS, nanoscale infrared spectroscopy, nanomaterials, chemical composition