Communication: atomic force detection of single-molecule nonlinear optical vibrational spectroscopy.Atomic Force Microscopy (AFM) allows for a highly sensitive detection of spectroscopic signals.  We show that, with proper phase matching, the AFM-detected signals closely resemble coherent heterodyne-detected signals.  Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).
AFM
This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime. 
NMR
This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime.  Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).
Raman