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Performances for broadband synchrotron photothermal infrared nano-spectroscopy at Diamond Light Source

DOI: 10.1016/j.infrared.2020.103238 DOI Help

Authors: Mark D. Frogley (Diamond Light Source) , Ioannis Lekkas (Diamond Light Source) , Chris S. Kelley (Diamond Light Source) , Gianfelice Cinque (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Infrared Physics & Technology

State: Published (Approved)
Published: February 2020

Open Access Open Access

Abstract: Broadband infrared nanospectroscopy with Synchrotron Radiation, via the atomic force microscope detection of photothermal expansion, was first demonstrated at the MIRIAM beamline of Diamond in 2016. Since then, the system has undergone significant developments and has been available to users in collaboration since January 2018. Continuous nano-FTIR spectra are so-far achieved with useful signal-to-noise in the 4000 – 800 wavenumber region and at around 100 nm spatial resolution (depending on sample geometry and thermal diffusion at the modulation frequency of the IR beam), for soft materials like single biological cells and polymers. Here we briefly describe the nanospectroscopy system and evaluate the performances through comparison of measured data for typical samples with theoretical expectations. Noise levels are shown to be cantilever thermal-noise limited at the first contact resonance currently employed, whilst signal levels are consistent with expectations for the focussed IR power density available from the IR beamline and using sinusoidal modulation of the beam tuned to the contact resonance frequency. Finally, planned enhancements of the performance, including access to higher cantilever contact resonances to reduce noise and increase spatial resolution, are discussed.

Journal Keywords: Infrared; Nanospectroscopy; Synchrotron; AFM

Subject Areas: Technique Development, Physics

Instruments: B22-Multimode InfraRed imaging And Microspectroscopy