Resolving Nanocomposite Interfaces via Simultaneous Submicrometer Optical-Photothermal Infrared-Raman Microspectroscopy

Nanocomposite materials are assuming increasingly important roles across contemporary materials science. Analytical characterizations and visualizations of nanoscale interphases/interfaces are critical to development of novel multiphase nanostructures and nanoscale systems. While conventional vibrational spectroscopies are indispensable physicochemical characterization tools, standard techniques such as Fourier-transform and quantum cascade laser infrared (IR) microspectroscopies are intrinsically limited in spatial resolution by the wavelength-dependent diffraction limit of IR light (approximate to 5-12 mu m). Optical-photothermal infrared (O-PTIR) with simultaneous hyperspectral Raman microspectroscopy (O-PTIR+R) is a novel all-optical technique that circumvents such diffraction limits, yielding position-specific IR spectra with sub-micrometer wavelength-independent resolution across the mid-IR. This work implements single-frequency O-PTIR with concomitant hyperspectral Raman microspectroscopy to resolve interfacial regions in a poly(octadecyl acrylate)-grafted-multiwall carbon nanotube (PODA-g-MWCNT) nanocomposite for wearable temperature sensors and highlights how the O-PTIR+R technique can be used for analytical characterization and visualization of other nanocomposite systems below resolution limitations of conventional IR spectroscopies.

Automated summary

Nanocomposite materials are increasingly important in contemporary materials science, and analytical characterization and visualization of nanoscale interphases/interfaces are critical for development of novel multiphase nanostructures. A novel optical-photothermal infrared technique with simultaneous hyperspectral Raman spectroscopy can overcome diffraction limits of standard infrared spectroscopies, providing position-specific IR spectra with sub-micrometer resolution across the mid-IR range. This technique was used to resolve interfacial regions in a specific nanocomposite material and has potential for analytical characterization and visualization of other nanocomposite systems below the resolution limitations of conventional IR spectroscopies.