TY - GEN
T1 - Terahertz and mid-infrared photoexpansion nanospectroscopy
AU - Lu, Feng
AU - Jin, Mingzhou
AU - Salih, Mohammed
AU - Dean, Paul
AU - Khanna, Suraj
AU - Li, Lianhe H.
AU - Davies, Giles
AU - Linfield, Edmund H.
AU - Belkin, Mikhail A.
PY - 2013
Y1 - 2013
N2 - We report a method of taking mid-infrared and terahertz absorption spectra on nanoscale using compact mW-level sources, such as quantum cascade lasers, and a standard atomic force microscope (AFM). Light absorption is detected via deflection of an AFM cantilever due to local sample thermal expansion. To enable detection of minute sample expansion, the repetition frequency of the laser pulses is moved in resonance with the cantilever mechanical frequency. Plasmonic enhancement under the apex of a sharp metalized AFM tip is also utilized to further improve the detection sensitivity. As a result, we are able to obtain high-quality absorption spectra from samples thinner than 10 nm. The spatial resolution is principally determined by the diameter of the high-intensity spot in the vicinity the AFM tip, and is below 50nm. This technique requires no optical detectors.
AB - We report a method of taking mid-infrared and terahertz absorption spectra on nanoscale using compact mW-level sources, such as quantum cascade lasers, and a standard atomic force microscope (AFM). Light absorption is detected via deflection of an AFM cantilever due to local sample thermal expansion. To enable detection of minute sample expansion, the repetition frequency of the laser pulses is moved in resonance with the cantilever mechanical frequency. Plasmonic enhancement under the apex of a sharp metalized AFM tip is also utilized to further improve the detection sensitivity. As a result, we are able to obtain high-quality absorption spectra from samples thinner than 10 nm. The spatial resolution is principally determined by the diameter of the high-intensity spot in the vicinity the AFM tip, and is below 50nm. This technique requires no optical detectors.
KW - Photoexpansion nanospectroscopy
KW - mid-infrared and terahertz spectroscopy
KW - plasmonic enhancement
KW - quantum cascade laser
KW - sub-wavelength resolution
UR - http://www.scopus.com/inward/record.url?scp=84878096534&partnerID=8YFLogxK
U2 - 10.1117/12.2000743
DO - 10.1117/12.2000743
M3 - Conference contribution
AN - SCOPUS:84878096534
SN - 9780819493545
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Terahertz and Ultrashort Electromagnetic Pulses for Biomedical Applications
T2 - Terahertz and Ultrashort Electromagnetic Pulses for Biomedical Applications
Y2 - 6 February 2013 through 7 February 2013
ER -