AFM measurements
were performed on a Nanoscope III digital instrument microscope in
tapping mode in air. Contact mode AFM was applied in water with a
contact SNL-10 silicon tip commercially available from Bruker. Vibration
frequency of the tip is chosen at around 7Hz to achieve a stable signal-to-noise
ratio in water. AFM images were processed and analyzed using the applications
WSxM and FabViewer.26 (link) The extinction spectra
were recorded by far-field extinction microspectroscopy in the 500–1000
nm spectral range. The spectrometer was coupled to an upright optical
microscope equipped with 50× (Olympus, numerical aperture NA
= 0.35) and 100× (Olympus, NA: 0.8) objectives for experiments
in air. Extinction spectra recorded in water at various temperatures
used a 100× immersion objective (Olympus, NA: 1). Raman spectra
were recorded using a Jobin-Yvon LABRAM HR 800 microspectrometer,
using a He–Ne laser excitation (632.8 nm) in backscattering
mode. For the experiments in water, the microscope was equipped with
a ×100 immersion objective (6.8 μW power). All spectra
were recorded within the 400–1800 cm–1 spectral
range.
were performed on a Nanoscope III digital instrument microscope in
tapping mode in air. Contact mode AFM was applied in water with a
contact SNL-10 silicon tip commercially available from Bruker. Vibration
frequency of the tip is chosen at around 7Hz to achieve a stable signal-to-noise
ratio in water. AFM images were processed and analyzed using the applications
WSxM and FabViewer.26 (link) The extinction spectra
were recorded by far-field extinction microspectroscopy in the 500–1000
nm spectral range. The spectrometer was coupled to an upright optical
microscope equipped with 50× (Olympus, numerical aperture NA
= 0.35) and 100× (Olympus, NA: 0.8) objectives for experiments
in air. Extinction spectra recorded in water at various temperatures
used a 100× immersion objective (Olympus, NA: 1). Raman spectra
were recorded using a Jobin-Yvon LABRAM HR 800 microspectrometer,
using a He–Ne laser excitation (632.8 nm) in backscattering
mode. For the experiments in water, the microscope was equipped with
a ×100 immersion objective (6.8 μW power). All spectra
were recorded within the 400–1800 cm–1 spectral
range.