We report on the development of a nonlinear optical microscopic technique based on two-photon absorption induced photothermal effect capable of detecting individual nonfluorescent nanoparticles with high sensitivity. The method which is inherently confocal makes use of near infrared excitation at high repetition rates and would be of interest in deep tissue imaging. We demonstrate the applicability of the technique by imaging single BaTiO3 nanoparticles, a potential biomolecular label having high photostability, in a scattering environment at fast time scales with a pixel dwell time of 80 μs.

We report on the design and construction of a laser scanning photothermal microscope and present images of gold nanoparticles of size as small as 5 nm. Laser scanning method allows fast image acquisition at 80 μs pixel dwell time so that a 500 × 500 pixel image is acquired in 20 s. Photothermal imaging at fast time scales can have potential applications in variety of fields including tracking of biomolecular transport processes.

We report on the development of a photothermal microscope capable of detecting and characterizing nonfluorescent metallic nanoparticles in a nanocomposite film. The distribution and number density of gold nanoparticles in Au/BaTiO3 nanocomposite films synthesized with different Au/Ba molar ratio is studied by the microscope.