| AVS 61st International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+AS-WeA |
| Session: | Nanoscale Imaging and Materials Characterization |
| Presenter: | Craig Prater, Anasys Instruments |
| Authors: | C.B. Prater, Anasys Instruments K. Kjoller, Anasys Instruments M. Lo, Anasys Instruments E. Dillon, Anasys Instruments R. Shetty, Anasys Instruments C. Marcott, Light Light Solutions F. Lu, University of Texas at Austin M. Jin, University of Texas at Austin M. Belkin, University of Texas at Austin A. Dazzi, Université Paris-Sud, France |
| Correspondent: | Click to Email |
The ability to perform chemical analysis at the nanoscale has been considered one of the “holy grails” of the scanning probe microscope community. Many techniques have been developed to provide material contrast in SPM images based on a variety of properties (electronic, optical, mechanical, etc.), but there had not been the ability to perform broadly applicable chemical analysis on diverse samples. We have developed AFM-based infrared spectroscopy (AFM-IR)1 that enables broadly applicable chemical analysis on samples with nanoscale spatial resolution and with sensitivity down to the scale of individual molecular monolayers. The AFM-IR technique illuminates a sample with light from a tunable infrared laser source and then uses the tip of an AFM to measure the sample’s local photothermal expansion due to the absorption of infrared light at specific wavelengths.2 Measuring absorption as a function of wavelength creates an IR absorption spectrum that acts as a chemical fingerprint to characterize and identify chemical components. Mapping IR absorption spatially over a sample at different wavelengths can be used to create maps of nanoscale chemical composition. Recently we have implemented two techniques to extend both the applicability and sensitivity of the AFM-IR technique. First, we implemented top side illumination to enable AFM-IR on a much wider array of samples and sample substrates. Second, we developed a resonance enhanced mode3 where the IR laser pulses are synchronized to a contact resonance of the AFM cantilever. Combined with “lightning rod” enhancement of the incident IR light, the resonance enhanced technique can achieve chemical analysis with single monolayer sensitivity4 and spatial resolution ~25 nm. We will describe the AFM-IR technique, recent innovations and applications in materials, life sciences, photonics, and semiconductors.
References:
1. A. Dazzi, R. P., F. Glotin, and J. M. Ortega. Opt. Lett. 2005, 30, 2388-2390.
2. Dazzi, A.; Prater, C. B.; Hu, Q.; Chase, D. B.; Rabolt, J. F.; Marcott, C. Appl. Spectrosc. 2012, 66, (12), 1365-1384.
3. Lu, F.; Belkin, M. A. Opt Express 2011, 19, (21), 19942-19947.
4. Lu, F.; Jin, M.; Belkin, M. A. Nat Photon 2014, 8, (4), 307-312.