Nano@Tech with Roshan Shetty
Nano@Tech welcomes Roshan Shetty, co-founder of Anasys Instruments, on "Nanoscale IR Spectroscopy using an AFM."
Due to current budget restraints on campus the Nano@Tech seminar series will be providing lunch only to those who have pre-registered.
The ability to unambiguously identify arbitrary material under the tip of an Atomic Force Microscope (AFM) has long been identified as one of the primary interests of users of probe microscopy. While the AFM has the ability to measure a range of material properties including mechanical, electrical, magnetic and thermal, the technique has lacked the robust ability to characterize and identify unknown materials. Infrared spectroscopy is a benchmark technique routinely used in a broad range of sciences to characterize and identify materials on the basis of specific vibrational resonances of chemical bonds. Several AFM probe-based techniques have been used to beat the diffraction limit of conventional IR measurements, including near field optical techniques. Other IR techniques are based on measuring the local temperature rise from spectral absorption through the use of temperature-sensing probes integrated with conventional Fourier Transform IR (FTIR) spectrometers. To our knowledge, however, none of these techniques provide readily interpretable broadband IR spectroscopy with nanoscale resolution. We have successfully integrated the capabilities of AFM with IR spectroscopy to allow chemical characterization on the micro and nanoscale. The instrument employs a technique called photothermal induced resonance (PTIR) that uses an AFM probe to measure the local thermal expansion from IR light incident upon a sample. This technique enables the ability to obtain a high quality IR spectrum at a selected point in an AFM image and/or automatically map spectra at an array of points on a sample to enable chemical mapping. In addition, local mechanical and thermal properties can be obtained from the sample. In this presentation, we will share the details of the measurement technique including application examples on polymer multilayers and blends, along with measurements on biological samples.