Broadband near-field infrared spectromicroscopy using photothermal probes and synchrotron radiation

DOI: 10.1364/OE.24.001852

Authors: Paul M. Donaldson (Diamond Light Source) , Chris S. Kelley (Diamond Light Source) , Mark D. Frogley (Diamond Light Source) , Jacob Filik (Diamond Light Source) , Katia Wehbe (Diamond Light Source) , Gianfelice Cinque (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Optics Express , VOL 24 (3) , PAGES 1852-1864

State: Published (Approved)
Published: January 2016
Diamond Proposal Number(s): 8960 , 10407

Abstract: In this paper, we experimentally demonstrate the use of infrared synchrotron radiation (IR-SR) as a broadband source for photothermal near-field infrared spectroscopy. We assess two methods of signal transduction; cantilever resonant thermal expansion and scanning thermal microscopy. By means of rapid mechanical chopping (50-150 kHz), we modulate the IR-SR at rates matching the contact resonance frequencies of atomic force microscope (AFM) cantilevers, allowing us to record interferograms yielding Fourier transform infrared (FT-IR) photothermal absorption spectra of polystyrene and cyanoacrylate films. Complementary offline measurements using a mechanically chopped CW IR laser confirmed that the resonant thermal expansion IR-SR measurements were below the diffraction limit, with a spatial resolution better than 500 nm achieved at a wavelength of 6 μm, i.e. λ/12 for the samples studied. Despite achieving the highest signal to noise so far for a scanning thermal microscopy measurement under conditions approaching near-field (dictated by thermal diffusion), the IR-SR resonant photothermal expansion FT-IR spectra measured were significantly higher in signal to noise in comparison with the scanning thermal data.

Subject Areas: Technique Development


Instruments: B22-Multimode InfraRed imaging And Microspectroscopy

Added On: 28/01/2016 11:53

Documents:
Broadband near-field infrared spectromicroscopy using photothermal probes and synchrotron radiation.pdf

Discipline Tags:

Physics Technique Development - Physics

Technical Tags:

Spectroscopy Infrared Spectroscopy Synchtron-based Fourier Transform Infrared Spectroscopy (SR-FTIR)