Hyper-Raman spectrometer

The hyper-Raman (HR) spectroscopy is interesting tool as a novel vibrational spectroscopy because it has an unique selection rule that is different from those of the IR absorption and Raman spectroscopy. Our system enables switching the 532 nm excitation (200 kHz, 300 mW, 15 ps) for HR and 266 nm excitation for UV resonance Raman spectroscopy with flipping mirrors.

The 266-nm emission line is obtained by doubling the frequncy of the 532 nm light with BBO (Beta Barium Borate) nonlinear crystal. The 532 and 266 nm are separated by Pellin-Broca prism and harmonic separator subsequently. The Glan-laser polarizer and half-wave plate makes the polarization light is horizontal, being suitable for the Raman measurements in this setup.



The 90 degree-scattering signal of HR (or UV-Raman) is collected with a 20x ultraviolet (UV) microscope objective lens (NA 0.4). Two high energy-pass filters (475-nm cut-off, OD 2) in HR and one 266-nm edge filter in UV-Raman. The signal is recorded by an LN2-cooled CCD detector after passing a monochromator.