Del Mar Photonics - Newsletter December 2010 - Newsletter April 2011
Can you do Raman spectroscopy or CARS with this setup? btw the carbon nanotubes are auto-fluorescence?
No and yes. This particular setup is optimized for continuous imaging and spectroscopy of fluorescent nanotubes which emit between ~ 900 and 1600 nm. It uses tunable cw laser which excite resonance absorption peaks of selected nanotube structures and a set of filters to transmit near-infrared nanotube emission and stop laser light. To detect Raman signals from nanotubes one would need better optics, e.g. specialized notch filters, to reject excitation and detect signals very close to the excitation wavelength. Perhaps even CARS would be possible if the laser is used in femtosecond mode (+ specialized optics and detectors), but it has not been tried here. Both Raman and CARS spectroscopy of individual nanotubes have been demonstrated by other research groups already.
Regarding autofluorescence (and without deviating much into definitions) - everything emits some photons with certain probability after absorption of light. The question is - with what probability? For nanotubes this value is yet to be defined. Estimates show that for selected nanotube structures (and in good environment like some inert gas) this probability, or quantum yield, may reach 0.1-0.2
Trestles LH femtosecond lasers with integrated DPSS DMPLH laser pump - DPSS DMPLH lasers
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