title: Control of phonons in semiconductor nanocrystals via femtosecond pulse chirp-influenced wavepacket dynamics and polarization.
abstract: The realistic electronic structure of semiconductor nanocrystals is characterized by excitonic fine structure and atomistic symmetry breakings that are challenging to resolve experimentally. Exciton-phonon coupling is one of the most sensitive measures of the excitonic wave functions of the nanocrystals. Here, we exploit this sensitivity via chirped pulse and polarization resolved femtosecond pump/probe spectroscopy of colloidal CdSe nanocrystals. Pulse chirp measurements and simulations are used to explore the contributions of excited- and ground-state vibrational wavepackets to the observed coherent phonons in the pump/probe signals. Polarization resolved pump/probe spectroscopy is used to explore electronic and vibrational polarization anisotropies. We find no electronic polarization anisotropy, whereas vibrational anisotropy is preserved.
authors.affiliation: Department of Chemistry, McGill University , Montreal, Quebec, Canada.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Mooney
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Saari
authors.forename: Anne Myers
authors.initials: AM
authors.lastname: Kelley
authors.forename: Michael M
authors.initials: MM
authors.lastname: Krause
authors.forename: Brenna R
authors.initials: BR
authors.lastname: Walsh
authors.forename: Patanjali
authors.initials: P
authors.lastname: Kambhampati