Wednesday June 29, 2005
4 PM - 5:30 PM
ENG Z-50 Auditorium

Office Hours:
Thursday June 30, 2005
3:30 PM - 4:30 PM
ENG 208

"Scattering SNOM of polymers and biomolecules"
Dr. Fritz Keilmann
Max-Planck-Institut fur Biochemie

Scanning near-field optical microscopy (SNOM) has overcome the diffraction limit, and has for the first time allowed to routinely employ long-wavelength infrared radiation for attaining 20 nm spatial resolution /1/. Based on scattering from commercial AFM tips, infrared nanoscopy provides tremendous chances for exploiting new types of image contrasts. Thus while visible microscopy is largely restricted to bound-electron transitions in fluorophores and dielectrics, infrared microscopy can in addition exploit mobile-electron transitions to characterize conductance phenomena /2/, and most widely usable, vibrational transitions that are chemically specific and thus allow local chemical recognition /3/. This lecture will introduce the function of scattering-type SNOM, describe its theory of image formation, and give recent results of local infrared spectra of polymer /4/ and biological nanostructures. 1 F. Keilmann and R. Hillenbrand, Near-field microscopy by elastic light scattering from a tip, Phil.Trans.R.Soc.Lond. A 787-805 (2004). 2 B. Knoll and F. Keilmann, Infrared conductivity mapping for nanoelectronics, Appl. Phys. Lett. 77, 3980 (2000). 3 B. Knoll and F. Keilmann, Near-field probing of vibrational absorption for chemical microscopy, Nature (London) 399, 134 (1999). 4 T. Taubner, R. Hillenbrand, and F. Keilmann, Nanoscale polymer identification by spectral signature in scattering infrared near-field microscopy, Appl. Phys. Lett. 85, 5064 (2004).