A tunable short-pulse laser system that is the heart of the SFG microscope at NANOCHEM has been installed at AAU. Test experiments demonstrate SFG using probe beams both in the range of electronic resonances and in the infrared vibrational spectroscopy range.
Sum frequency generation spectroscopy is a surface and interface sensitive process. It yields high detection efficiency with a signal in the visible region. The method can have high time resolution and resolve the molecular orientation. As different selection rules apply it is complementary to linear spectroscopy and Raman.
The setup requires two incident laser beams that penetrate the medium to investigate. The signal is generated when the frequencies match discrete states in the medium and a sum frequency signal is emitted in the direction of the sum of the wavevectors of the incident beams.
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