[Zurück]

G. Ramer, A. Balbekova, B. Lendl:
"Time Resolved Photothermal Expansion Infrared Nanoscopy";
Vortrag: CEITEC Annual Conference, Brno, Czech Republic (eingeladen); 21.10.2014 - 24.10.2014; in: "Book of Abstracts CEITEC Annual Conference "Frontiers in Material and Life Sciences "", Masarykova Univerzita, Brno, 978-80-210-7159-9, (2014), ISBN: 978-80-210-7159-9; S. 41.

Recent developments in the field of scanning probe microscopy have made infrared imaging
and spectroscopy below the diffraction limit possible. Spatial resolutions below 50 nm can now
be reached for mid-infrared (MIR) wavelengths using either scattering scanning near field optical
microscopy (sSNOM) [1,2] or photothermal expansion microscopy (atomic force microscope
induced resonance, AFMIR) [3,4]. Both methods have in common that they use a tuneable MIR
laser as a light source. This use of a monochromatic source makes imaging of the absorption at
a single wavelength across the sample during a standard topographic scan of the surface easily
possible. However, it also implies that to acquire a full spectrum the laser has to step through all
the wavelengths that are to be recorded. Accordingly, the time it takes to acquire one spectrum
with a commercially available infrared nanoscopy instrument is in the range of a minute
or more.
Here we present our first steps towards time resolved infrared spectroscopy over a broad
wavelength range ( > 100 cm
-1
) using photothermal expansion microscopy. Through the use of
a Daylight solutions external cavity quantum cascade laser (EC-QCL) which can be quickly
sweeped across its tuning range a time resolution in the range of 10 s or better can been achieved.
We explain the working principle of this method and demonstrate how it can be used to analyze
changes in the secondary structure of proteins over time.
1. N. Ocelic, A. Huber, and R. Hillenbrand, Appl. Phys. Lett.
89
, 101124 (2006).
2. F. Huth, A. Govyadinov, S. Amarie, W. Nuansing, F. Keilmann, and R. Hillenbrand, Nano Lett.
12
,
3973 (2012).
3. A. Dazzi, R. Prazeres, F. Glotin, J. M. Ortega, M. Al-Sawaftah, and M. de Frutos, Ultramicroscopy
108
, 635 (2008).
4. F. Lu, M. Jin, and M. A. Belkin, Nat. Photonics
8
, 307 (2014).

http://publik.tuwien.ac.at/files/PubDat_234383.pdf