Chemical Imaging of the Surface of Self-Assembled Polystyrene-b-Poly(methyl methacrylate) Diblock Copolymer Films Using Apertureless Near-Field IR Microscopy

Abstract

The nanoscale chemical composition variations of the surfaces of thin films of polystyrene- b-poly(methyl methacrylate) (PS- b-PMMA) diblock copolymers are investigated using apertureless near-field IR microscopy. The scattering of the incident infrared beam from a modulated atomic force microscopy (AFM) tip is probed using homodyne detection and demodulation at the tip oscillation frequency. An increase in the IR attenuation is observed in the PMMA-rich domains with a wavenumber dependence that is consistent with the bulk absorption spectrum. The results indicate that even though a small topography-induced artifact can be observed in the near-field images, the chemical signature of the sample is detected clearly.

Chemical Imaging of Spatial Heterogeneities in Catalytic Solids at Different Length and Time Scales

“…[107] Other interesting avenues based on near-field spectroscopy concepts include the use of scanning near field infrared microscopy (SNIM) [108] and terahertz near-field microscopy. [109] The former method allows label-free spectroscopy by measuring local infrared spectra with a spatial resolution down to 30 nm.…”

Nanoscale Conductivity Contrast by Scattering-Type Near-Field Optical Microscopy in the Visible, Infrared and THz Domains

“…5 Mid-infrared near-field microscopy of highly-doped semiconductors Much of the advancement of s-SNOM has been attained using the CO 2 and CO lasers, in the 9-11µm and 5-6µm wavelength regions, respectively [5,6,8,10,11,20,21,24,[27][28][29][30][31][32][33][34][35][36][37]. This came first of all because mid-infrared can be used to exploit chemical fingerprints for recognizing chemical composition, now at nanometric resolution [8,31,33,37,38], but furthermore for technical reasons.…”

“…This came first of all because mid-infrared can be used to exploit chemical fingerprints for recognizing chemical composition, now at nanometric resolution [8,31,33,37,38], but furthermore for technical reasons. Compared to the visible and near infrared regionswhere also simple lasers with ideally 1 to 10 mW c.w.…”

Phase stabilized homodyne of infrared scattering type scanning near-field optical microscopy

“…The imaginary part of the near-field scattered signal corresponds to the near-field absorption of the sample. 16,17 A phase stabilization mechanism for stabilization of interferometric homodyne detection is developed to reduce the noise from phase instability. An auxiliary interferometer is juxtaposed with the above-mentioned infrared interferometer such that auxiliary interferometer shares almost the same optical path as the infrared laser in the main interferometer.…”