Investigating Ultrafast Photoinduced Processes of Natural and Model Light Harvesting Systems Through Ultrafast Non-Linear Electronic Spectroscopies / Dabin Kim.

Format:

Book

Thesis/Dissertation

Author/Creator:

Kim, Dabin, author.

Contributor:

University of Pennsylvania. Chemistry, degree granting institution.

Language:

English

Subjects (All):

Physical chemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Local Subjects:

Physical chemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Physical Description:

1 online resource (246 pages)

Contained In:

Dissertations Abstracts International 84-08B.

Place of Publication:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2022.

Ann Arbor : ProQuest Dissertations & Theses, 2022

Language Note:

English

Summary:

Understanding the mechanism of photoinduced energy transfer and charge transfer involving excitonic states of multichromophoric assemblies is essential for understanding the high quantum efficiencies of natural photosynthetic complexes and developing design principles for artificial photosynthetic devices and organic photovoltaic materials. However, studying multichromophoric systems can be challenging due to their structural complexity and overlapping spectral features Two-dimensional electronic spectroscopy (2DES) can be used to help alleviate spectral congestion and gain insight into energy transfer pathways in multichromophoric assemblies. Another approach is to investigate structurally simpler model systems that mimic certain aspects of multichromophoric assemblies. In this thesis I take both approaches. I apply 2DES to photosystem I (PSI), a large natural multichromophoric assembly, and I investigate structurally simpler dimeric metallo-based dipyrrin complexes. Photosystem I (PSI) is one of nature's most efficient energy converters, and recent studies have found that chlorophyll f (Chl f) containing PSI complexes can expand the spectral region for photosynthesis the red region. I applied 2DES to Chl f containing PSI complexes to map the pathways of energy transfer involving more red-shifted states. The 2DES spectra show evidence of downhill energy transfer to the red shifted Chls as a growth in the cross peak region. Additional insight is gained by applying a global analysis to the 2DES spectra. I compare the 2DES and 2D-DAS for the Chl f containing PSI complexes and the corresponding Chl a containing counterpart to gain further insight into how Chl f molecules impact energy transfer. The 2D-DAS result show that Chl f states alter the trapping time and mechanism of energy transfer in PSI complexes.I have also investigated a bi-dentate zinc π-extended dipyrrin complex, Zn(BDP)2, as a model light harvesting complex via femtosecond transient absorption (fsTA) and two-dimensional electronic spectroscopy (2DES). From fsTA I found that Zn(BDP)2 forms an intermediate state with charge transfer character on the 5-14 ps timescale that then evolves to form a triplet state on the 370-630 ps timescale, where the timescales depend on solvent polarity. From 2DES I (1) characterized the excitonic states of Zn(BDP)2 and observed ultrafast exciton relaxation and (2) extracted oscillatory components that are assigned to excited state coherences.

Notes:

Source: Dissertations Abstracts International, Volume: 84-08, Section: B.

Advisors: Anna, Jessica M; Committee members: Lester, Marsha I.; Vinogradov, Sergei; Fakhraai, Zahra.

Department: Chemistry.

Ph.D. University of Pennsylvania 2022.

Local Notes:

School code: 0175

ISBN:

9798374412277

Access Restriction:

Restricted for use by site license.

This item is not available from ProQuest Dissertations & Theses.