ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
A scanning near-field microscope that allows the fast acquisition of midinfrared absorption spectra is described. The microscope couples the nanoscale spatial resolution of a scanning probe microscope with the chemical specificity of vibrational spectroscopy. Key design elements of the microscope include a tunable broadband infrared light source; an infrared focal plane array-based spectrometer which allows parallel detection of the entire pulse bandwidth (200 cm−1); and a single mode, fluoride glass, near-field probe fabricated with a chemical etching protocol. Infrared transmission images of a micropatterned thin gold film are presented that demonstrate spatial resolution conservatively estimated to be λ/7.5 at 3.4 μm, in the absence of optical artifacts due to topography. Constant height mode images of a polymer nanocomposite demonstrate instrumental sensitivity to fractional transmission changes of 1×10−3. Near-field absorption spectra (λ=3.4 μm) of a 2 μm thick polystyrene film are presented which demonstrate the instrumental sensitivity required for high spatial resolution, near-field absorption imaging. These spectra are acquired in 2 s and indicate a film thickness detection limit for polystyrene of 200 nm. Measurements exploring the coupling between the infrared absorption magnitude and changes in tip–sample separation suggest that near-field absorption imaging is relatively insensitive to topographic artifacts.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1309034
