Hyper-Raman Microspectroscopic System
Hyper-Raman (HR) Microspectroscopic System
- Hyper Raman scattering
- Although signal light intensity is very weak, HR spectra provide unique spectroscopic information.
- Vibrational selection rule
- All IR active modes are HR active
→ Posssible alternative to IR microscopy - IR/Raman inactive modes can be HR active
- Resonance HR scattering
- Information on two-photon allowed electronic states can be obtained.
Fig. 1. Energy Diagram
Experimental Setup
Spectral resolution: ∼10cm-1, Excitation power: <8mW
Fig. 2. Setup
Fig. 3. Apparatus
Results
IR active vibrational imaging with sub-micrometer spatial resolution is achieved
Fig. 4. IR active vibrational image of all-trans-β-carotene microcrystall
A new phenomenon was discovered!! Solvent HR signal enhancement by solute molecules:
Fig. 5. HR spectrum of all-trans-β-carotene in solution showed enhanced solvent HR signals which correspond very well to strong IR bands of solvent.