Dr. D. Victor Suvisesha Muthu
Raman scattering is a powerful probe for characterization and to unravel basic science behind many novel phenomena in physics. It is a contactless method
with high spatial resolution (~ 1 micron). It is very sensitive to external and internal perturbations like strain, electric fields, temperature and pressure. We study
systems under low temperature ( up to 4 K ) and at high pressure ( up to 30 GPa). We have studied many interesting systems like carbon and boron nitride
nanotubes, pyrochlores, topological insulators, iron pnictide superconductors using Raman spectroscopy. Most of these studies were carried out in collaboration
with Prof. A.K. Sood’s group.
1) Single monochromator based Raman Spectrometer:
We have built a micro Raman spectrometer in the lab based on a single monochromator. It uses a single grating 0.5 m monochromator (Jobin Yvon iHR550 model)
to disperse the light and a notch filter to reject the laser line. The sample is excited with 532 nm laser line using an air cooled diode pumped solid state laser (DPSS).
A 50 X objective is used to focus the laser beam (spot size ~ 3 µm) and also to collect the scattered light. The scattered light from the sample is detected with a back
illuminated CCD. It is a very simple system but the through put is very high so that experiments under ultra high pressure can be carried out.
2) Diamond anvil cells for high pressure Raman measurements:
We have a Mao-Bell type diamond anvil cell which contains two gem quality diamonds facing each other with a flat face of 600 micron. Samples will be placed
and squeezed in between the diamonds and pressures up to 30 GPa (3,00,000 atm) can be achieved.