PhD Defense

Wednesday, January 23, 2019
2:30pm – 4:30pm

Storrs Campus
GW103A

Soroush Khosravi Dehaghi, Department of Physics, University of Connecticut

Femtosecond Laser Transient Spectroscopy of Carotenoids and Carbon Nanotubes

Carotenoids and semiconducting single-wall carbon nanotubes, which are both nanoscale carbon-based quantum mechanical systems, were studied using different optical spectroscopy techniques.

The lifetime of the S$$_2$$ excited state of the carotenoids were estimated using a model-based lifetime analysis routine. It was found that the addition of a conjugated carbonyl group to the carotenoid has several crucial effects on the optical response due to the alteration of the delocalized conjugated $$\pi$$ molecular orbital of the molecule. These effects include the shortening of the lifetimes of the excited states, the change in the decay mechanism from the S$$_2$$ excited state to the S$$_1$$ excited state, and the unresolved vibrational peaks in the steady-state absorption spectrum.

The decay of the E$$_{22}$$ excited state of (6,5) semiconducting carbon nanotube dispersed in flavin mononucleotide with water was observed using transient grating spectroscopy. The lifetime of this excited state was estimated to be 450 ± 50 fs. A very strong single-frequency oscillatory component was observed in the transient grating decay profile.

Contact:

Prof. N. Berrah

Physics Department (primary)