DCMPMS Seminars

Realizing Atomic Resolution Vibrational Spectroscopy

by Dr. Kartik Venkatraman (Center for Nanophase Materials Sciences, Oak Ridge National Laboratory)

Monday, December 6, 2021 from to (Asia/Kolkata)
at Zoom link : https://zoom.us/j/98486388327 Meeting ID : 984 8638 8327 Passcode : 784120
Zoom link : https://zoom.us/j/98486388327 Meeting ID : 984 8638 8327 Passcode : 784120
Vibrational spectroscopy has become a ubiquitous characterization tool
in materials science, revealing compositional information and yielding
spectral fingerprints for atomic bonding arrangements. Traditional
vibrational spectroscopies based on infrared photon absorption, visible
photon scattering, and inelastic neutron scattering boast of sub-meV
energy resolution but suffer from poor (~1 μm) spatial resolution.
Near-field infrared and optical vibrational spectroscopies have
demonstrated significant improvement in spatial resolution, routinely
yielding ~50 nm. Such spatial resolution still limits characterization
of individual nanoparticles or atomic to nanoscale heterogeneities like
defects and interfaces in materials. In 2014, a novel vibrational
spectroscopy was realized which combines 1Å spatial resolution routinely
achievable in an aberration-corrected scanning transmission electron
microscope (STEM) with 3 – 8 meV energy resolution achievable using
monochromated electron energy-loss spectroscopy (EELS). Since its
realization, vibrational spectroscopy with monochromated STEM EELS has
seen tremendous progress like performing damage-free nanoscale detection
for both organic and inorganic specimens, measuring temperature in
nanometer-sized areas with 1 K precision, determining the phonon
dispersion in individual nanoparticles, demonstrating atomic resolution,
etc., which has impacted a wide variety of important scientific
problems. In this talk, I will present my contribution to this field
interlaced with seminal contributions from researchers all around the