Enhancing PNNL’s Optical Microscopy and Spectroscopy Capabilities
A new combined atomic force microscopy – optical spectroscopy capability characterizes ultralow frequency vibrations, or phonons, in low-dimensional and quantum materials. The new system images phonons with nanometer spatial and femtosecond temporal resolution. Initial time-domain measurements that track excitons and phonons in real time and frequency domain measurements that track excitons and phonons in real space have been separately established as the final system is developed.
New Custom-Built Nano-Optical Instrument
The new nanoimaging platform combines atomic force microscopy, ultralow frequency Raman spectroscopy, and ultrafast pump-probe spectroscopy. The combination of atomic force microscopy and ultralow frequency Raman spectroscopy enables tip-chemical and structural (<50 cm-1) nano-imaging and nano-spectroscopy via broad band tip-enhanced Raman scattering. The combination of atomic force microscopy and ultrafast pump-probe spectroscopy minimally allows correlated nano-topographic and time domain pump-probe measurements that track both excitons and phonons with femtosecond temporal resolution. The combination of high spatial and temporal resolution in a single measurement is still under development.
Main Specifications:
- Ability to probe vibrational modes down to ~5 cm-1 in Raman spectroscopy
- Spectral resolution down to ~3 cm-1 in optical spectroscopy
- Time resolution reaching ~15 femtoseconds in pump-probe measurements
- Spatial resolution of ~2 nm in Raman and photoluminescence spectral imaging