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Excited-State Dynamics in Vanadium(II) Polypyridyl Complexes and Singlet Fission Systems : = Exploring the Role of Spin with Optical and Magnetic Resonance Spectroscopy.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Excited-State Dynamics in Vanadium(II) Polypyridyl Complexes and Singlet Fission Systems :/
其他題名:	Exploring the Role of Spin with Optical and Magnetic Resonance Spectroscopy.
作者:	Dill, Ryan Daniel.
面頁冊數:	1 online resource (243 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-02, Section: B.
Contained By:	Dissertations Abstracts International84-02B.
標題:	Physical chemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29322419click for full text (PQDT)
ISBN:	9798845408891

Excited-State Dynamics in Vanadium(II) Polypyridyl Complexes and Singlet Fission Systems : = Exploring the Role of Spin with Optical and Magnetic Resonance Spectroscopy.
Dill, Ryan Daniel.

Excited-State Dynamics in Vanadium(II) Polypyridyl Complexes and Singlet Fission Systems :Exploring the Role of Spin with Optical and Magnetic Resonance Spectroscopy. - 1 online resource (243 pages)

Source: Dissertations Abstracts International, Volume: 84-02, Section: B.

Thesis (Ph.D.)--University of Colorado at Boulder, 2022.

Includes bibliographical references

Excited states produced by absorption of visible light can engage in unique and varied chemistry and physics, and they are used in many important applications like photovoltaics, lasers, some qubit materials, and photoredox catalysis. We investigate excited states in several materials, using electronic and magnetic resonance spectroscopy. First is a phthalocyanine that engages in intersystem crossing. The simple photophysics serve as useful background for the following chapters, and help demonstrate a combined technique, photoinduced absorption detected magnetic resonance (PADMR), that we developed to study the correlations between electronic and magnetic transitions. PADMR is a special case of ODMR (O = optically). ODMR is a spectroscopic method, but is also used for some quantum information technologies.Motivated by the need for cheap, stable, earth-abundant compounds with redox active photoexcited states, we also investigate vanadium(II) polypyridyl complexes. We find that the excited state manifold has more mixed character than traditional ligand field theory would suggest. This mixing derives from orbital overlap between unpaired ligand- and metal-centered electrons, stabilizing low-spin states and accelerating non-radiative relaxation. The gaps between low- and high-spin states are described by the spin-spin exchange interaction.Similar exchange interactions are important for singlet fission (SF) materials. SF initially produces a biexciton state, an exchange-coupled pair of triplets which, in some cases, may dissociate to two separate triplets. This biexciton formation process can improve photovoltaic efficiencies and may have quantum information applications. We discuss two SF materials. The first, a rigid, covalently bound pentacene dimer, produces a quintet state, 5TT, with high sublevel purity. That quintet state can be coherently driven with microwaves for over a microsecond. Long-lived coherences are important for quantum information science. The other SF material, which we study with low-temperature PADMR spectroscopy, is a neat polycrystalline film of a pentadithiophene derivative. The PADMR signals suggest that 1TT dissociation events are quickly followed by re-association of the spin-correlated component triplets. This "geminate" re-association pathway has been seen in ODMR data, but we show that ODMR spectroscopy is sensitive to this relaxation mechanism even if the triplet sublevel populations are exactly equal, in stark contrast to EPR spectroscopy.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798845408891Subjects--Topical Terms:

1981412
Physical chemistry.
Subjects--Index Terms:

ODMRIndex Terms--Genre/Form:

542853
Electronic books.

Excited-State Dynamics in Vanadium(II) Polypyridyl Complexes and Singlet Fission Systems : = Exploring the Role of Spin with Optical and Magnetic Resonance Spectroscopy.
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504 $a Includes bibliographical references
520 $a Excited states produced by absorption of visible light can engage in unique and varied chemistry and physics, and they are used in many important applications like photovoltaics, lasers, some qubit materials, and photoredox catalysis. We investigate excited states in several materials, using electronic and magnetic resonance spectroscopy. First is a phthalocyanine that engages in intersystem crossing. The simple photophysics serve as useful background for the following chapters, and help demonstrate a combined technique, photoinduced absorption detected magnetic resonance (PADMR), that we developed to study the correlations between electronic and magnetic transitions. PADMR is a special case of ODMR (O = optically). ODMR is a spectroscopic method, but is also used for some quantum information technologies.Motivated by the need for cheap, stable, earth-abundant compounds with redox active photoexcited states, we also investigate vanadium(II) polypyridyl complexes. We find that the excited state manifold has more mixed character than traditional ligand field theory would suggest. This mixing derives from orbital overlap between unpaired ligand- and metal-centered electrons, stabilizing low-spin states and accelerating non-radiative relaxation. The gaps between low- and high-spin states are described by the spin-spin exchange interaction.Similar exchange interactions are important for singlet fission (SF) materials. SF initially produces a biexciton state, an exchange-coupled pair of triplets which, in some cases, may dissociate to two separate triplets. This biexciton formation process can improve photovoltaic efficiencies and may have quantum information applications. We discuss two SF materials. The first, a rigid, covalently bound pentacene dimer, produces a quintet state, 5TT, with high sublevel purity. That quintet state can be coherently driven with microwaves for over a microsecond. Long-lived coherences are important for quantum information science. The other SF material, which we study with low-temperature PADMR spectroscopy, is a neat polycrystalline film of a pentadithiophene derivative. The PADMR signals suggest that 1TT dissociation events are quickly followed by re-association of the spin-correlated component triplets. This "geminate" re-association pathway has been seen in ODMR data, but we show that ODMR spectroscopy is sensitive to this relaxation mechanism even if the triplet sublevel populations are exactly equal, in stark contrast to EPR spectroscopy.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
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653 $a PADMR
653 $a Polypyriyl
653 $a Singlet fission
653 $a Transient
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