München 2004 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 31: Poster Nichtlineare optische Effekte und Lichtquellen

Q 31.10: Poster

Donnerstag, 25. März 2004, 14:00–16:00, Schellingstr. 3

Combining near field microscopy and coherent infrared spectroscopy — •Markus Brehm and Fritz Keilmann — Max-Planck-Institut für Biochemie, 82152 Martinsried

Imaging the optical properties of samples with a resolution much better than the wavelength is now possible using a scanning nearfield infrared microscope (SNIM)[1]. By using the locally confined near field at an AFM tip one can overcome the Abbe-limit and obtain a spatial resolution of some 10nm even at wavelengths of 10µ m.

Coherent infrared sources are needed to provide sufficient illumination intensity at the tip. Up to now we use gas lasers (CO₂ and CO) for this purpose.

One of the major advantages of using infrared light is the chance to exploit fingerprint vibrational absorption. To go beyond the limited spectral range of gas lasers, we plan to use a broadband, coherent source based on difference frequency generation from Ti:Sapphire femtosecond lasers [2]. This would allow material identification on the nanometer scale.

References:

1. T. Taubner, R. Hillenbrand, and F. Keilmann, No-dqPerformance of visible and mid-infrared scattering-type near-field optical microscopesNo-dq, Journal of Microscopy 210, 311-314 (2003).

2. F. Keilmann, C. Gohle, and R. Holzwarth, No-dqTime-domain mid-infrared frequency-comb spectrometerNo-dq, submitted