Presented by: Curtis Marcott, Light Light Solutions LLC and University of Delaware
Fourier transform infrared (FTIR) spectrometry has been a powerful capability for scientific research and industrial problem-solving for over 50 years now. There are, however, some limitations that have prevented its adoption in many applications, including the fact that its spatial resolution is limited by diffraction physics to around 5 to 10 µm. Two new approaches are described that can circumvent these limitations. A photothermal infrared response is induced when a specific IR pump laser wave number excites molecular vibrations in a sample. When the resulting photothermal response is detected using the tip of an atomic force microscope (AFM), full IR spectra or single wave number IR images can be obtained at spatial resolutions of 10 nm on samples as thin as a single monolayer. When a visible laser source is used in place of an AFM to sense the photothermal response, spatial resolutions around 500 nm are achievable, independent of the IR pump laser wave number, without any sample contact. Because only light actually absorbed by the sample is measured, both AFM-IR and optical photothermal infrared (O-PTIR) spectra closely match those found in digital databases of thin-film transmission IR spectra. In addition, the O-PTIR approach enables the simultaneous measurement of IR and Raman spectra at the same sample location and spatial resolution, well below the IR diffraction limit. Applications of these two approaches to a wide variety of sample types in the materials and life sciences are presented.
About the presenter
Curtis Marcott, Ph.D., is a Senior Partner at Light Light Solutions LLC, a spectroscopic consulting firm. A former research fellow at Procter & Gamble, Curt was the 2011 President of the Society of Applied Spectroscopy and is a member of the editorial advisory board of Applied Spectroscopy. He is a past member of the editorial advisory boards of Analytical Chemistry and Vibrational Spectroscopy, the A-page advisory panel of Analytical Chemistry, and the board of managers of the Coblentz Society. He served as program committee chairman for the 2009 FACSS Conference and the Sixth International Conference on Advanced Vibrational Spectroscopy (ICAVS-6). Dr. Marcott received the 1993 Williams-Wright Award from the Coblentz Society for achievement in vibrational spectroscopy, and was named the 2001 Cincinnati Chemist of the Year. He published a landmark paper on laboratory FT-IR hyperspectral imaging in 1995, and has been intimately involved with the development of nano-IR imaging, giving invited seminars around the world.