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Near-field fluorescence spectra with subdiffraction limit spatial resolution have been taken in the proximity of mitochondrial membrane inside breast adenocarcinoma cells (MCF7) treated with the fluorescent dye (JC-1) by using a scanning near-field optical microscope coupled with a confocal laser microspectrofluorometer. The probe–sample distance control is based on a piezoelectric bimorph shear force sensor having a static spring constant k=5 μN/nm and a quality factor Q=40 in a physiological medium of viscosity η=1.0 cp. The sensitivity of the force sensor has been tested by imaging a MCF7 cell surface.

A near-field optical device has been developed to collect sum frequency signal, generated in an AsGa single crystal sample by two pulsed lasers, one fixed at a wavelength of 532 nm and the other tunable in midinfrared. The sum frequency signal was collected with an uncoated silica tip. When the tip sample distance was increased, a strong decrease of the collected sum frequency signal was observed: the signal was divided by 2 for an increase of about 100 nm of the distance between the nanoprobe end and the sample surface. Without demonstrating submicronic lateral spatial resolution, this letter is, however, a first step towards a microscopic device of sum frequency generation spectroscopy.

The combination of internal photoemission and near‐field optics is proposed as a generally applicable approach to study the lateral variations of solid interface properties such as energy barriers and electron‐hole recombination rates. A successful test on Pt–GaP is described in which topographic and nontopographic phenomena are revealed, in particular recombination rate variations and small lateral changes of the Schottky barrier height.