Dr Centrone's team reported on experiments that carefully studied the AFM-IR signal strength versus sample thickness. The experiments showed that the AFM-IR signal increases linearly with thickness for samples up to 1µm thick. This observed linearity may pave the way for quantitative chemical analysis at the nanoscale.
Schematic to show the operation of AFM-IR
AFM-IR has recently attracted great interest in that it enables chemical identification and imaging with nanoscale resolution. In this paper, NIST reports on electron beam nanopatterned polymer samples which were fabricated directly on zinc selenide prisms and used to experimentally evaluate the AFM-IR signal lateral resolution, sensitivity and linearity. The authors have shown that the AFM-IR lateral resolution for chemical imaging is comparable to the lateral resolution obtained in the AFM topography. Spectra and chemical maps were produced from samples as thin as 40 nm. The observations also provide experimental confirmation of theoretical predictions on AFM-IR previously developed by Prof Alexandre Dazzi of Univ of Paris-Orsay who is also the inventor of the technique.
The patented AFM-IR technique is available commercially as the nanoIR™ platform from Anasys Instruments, Santa Barbara, CA. In AFM-IR, a rapidly pulsed infrared (IR) laser is directed on upon a thin sample which absorbs the IR light and undergoes rapid thermomechanical expansion. An AFM tip in contact with the sample resonates in response to the expansion, and this resonance is measured by the AFM. "We are excited by this through work by Dr. Centrone and his colleagues," said Craig Prater, Chief Technology Officer of Anasys Instruments. "We applaud NIST's research and involvement in advancing nanoscale characterization of materials using AFM-based spectroscopy."
About Anasys Instruments
Anasys Instruments is dedicated to delivering innovative products and solutions that analyze samples with spatially varying physical and chemical properties at the micro and nanoscale. Anasys Instruments introduced the nanoTA in 2006 which pioneered the field of nanoscale thermal property measurement. In 2010, Anasys Instruments proudly introduced the award-winning breakthrough nanoIR™ Platform which pioneered the field of nanoscale IR measurement. For further details, please visit www.anasysinstruments.com