Doubly Resonant Internally Heterodyne Phase Resolved Vibrational Sum Frequency Generation spectroscopy

Advancements in sum frequency generation spectroscopy have expanded its versatility in recent years. Despite this little investigation into the synergistic combination of advanced approaches has been reported. Here we combined the signal enhancing doubly resonant excitation scheme, which probes the vibronic structure of the sample, with the phase resolving capabilities of internally heterodyne phase resolved detection. Ultimately this combination of technique demonstrates the influence that the electronic transition involved in doubly resonant sum frequency generation has on the surface susceptibility, in tandem with acquisition of the chemical and electronic sample dependent response.