Recent Publications

Figure 5 of the article

Triplet-Pair Spin Signatures from Macroscopically Aligned Heteroacenes in an Oriented Single Crystal

The photo-driven process of singlet fission generates coupled triplet pairs (TT) with fundamentally intriguing and... Read more
Figure 1 of article

Entangled, Spin-polarized Excitons from Singlet Fission in a Rigid Dimer

Singlet fission, a process that splits a singlet exciton into a biexciton, has promise in... Read more
Clock transition between two conical intersections

Clock Transitions Guard Against Spin Decoherence in Singlet Fission

Short coherence times present a primary obstacle in quantum computing and sensing applications. In atomic... Read more
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Multidimensional Nano-Imaging of Structure, Coupling, and Disorder in Molecular Materials

A hierarchy of intramolecular and intermolecular interactions controls the properties of biomedical, photophysical, and novel... Read more
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Singlet fission for quantum information and quantum computing: the parallel JDE model

Singlet fission is a photoconversion process that generates a doubly excited, maximally spin entangled pair... Read more
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The Motion of Trapped Holes on Nanocrystal Surfaces

This Perspective discusses the phenomenon of trapped-hole diffusion in colloidal semiconductor nanocrystals. Surface charge-carrier traps... Read more

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Figure 5 of the article

Triplet-Pair Spin Signatures from Macroscopically Aligned Heteroacenes in an Oriented Single Crystal

The photo-driven process of singlet fission generates coupled triplet pairs (TT) with fundamentally intriguing and potentially useful properties. The quintet 5TT0 sublevel is particularly interesting for quantum information because it is highly entangled, addressable with microwave pulses, and could be detected using optical techniques. Previous theoretical work on a model...

Figure 1 of article

Entangled, Spin-polarized Excitons from Singlet Fission in a Rigid Dimer

Singlet fission, a process that splits a singlet exciton into a biexciton, has promise in quantum information. We report time-resolved electron paramagnetic resonance measurements on a molecule, TIPS-BP1′, designed to exhibit strongly state-selective relaxation to specific magnetic spin sublevels. The resulting optically pumped "spin polarization" is a nearly pure initial...

Clock transition between two conical intersections

Clock Transitions Guard Against Spin Decoherence in Singlet Fission

Short coherence times present a primary obstacle in quantum computing and sensing applications. In atomic systems, clock transitions (CTs), formed from avoided crossings in an applied Zeeman field, can substantially increase coherence times. We show how CTs can dampen intrinsic and extrinsic sources of quantum noise in molecules. Conical intersections...

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Singlet fission for quantum information and quantum computing: the parallel JDE model

Singlet fission is a photoconversion process that generates a doubly excited, maximally spin entangled pair state. This state has applications to quantum information and computing that are only beginning to be realized. In this article, we construct and analyze a spin-exciton hamiltonian to describe the dynamics of the two-triplet state...

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Polarizable molecules in the vibrational spectroscopy of water

We examine the role of electronic polarizability in water on short (tens of femtoseconds), intermediate (hundreds of femtoseconds), and long (≈1 ps) time scales by comparing molecular dynamics results to experimental data for vibrational spectroscopy of HOD in liquid D 2 O. Because the OH absorption frequency is sensitive to...

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The subdiffusive targeting problem

Recent experiments in living cells have observed subdiffusive motion, where the mean squared displacement of a molecule grows sublinearly with time as 〈 x 2 〉∼ t α . Motivated by these experiments, we develop a theory for subdiffusion-limited bimolecular enzyme kinetics. As in normal diffusion, the statistics of the...

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Carrier transport in heterojunction nanocrystals under strain

We present a theory for carrier transport in semiconducting nanoscale heterostructures that emphasizes the effects of strain at the interface between two different crystal structures. An exactly solvable model shows that the interface region, or junction, acts as a scattering potential that facilitates charge separation. As a case study, we...

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A microscopic model of singlet fission

Singlet fission, where an electronically excited singlet on one chromophore converts into a doubly excited state on two, has gone from a curiosity in organic photophysics to a potential pathway for increasing solar energy conversion efficiencies. Focusing on the role of solvent-induced energy level fluctuations that would be present in...

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The tunable hydrophobic effect on electrically doped graphene

Using molecular dynamics simulations, we study the hydrophobic effect on electrically doped single layer graphene. With doping levels measured in volts, large changes in contact angle occur for modest voltages applied to the sheet. The effect can be understood as a renormalization of the surface tension between graphene and water...

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Tetracene aggregation on polar and nonpolar surfaces: Implications for singlet fission

In molecular crystals that exhibit singlet fission, quantum yields depend strongly on intermolecular configurations that control the relevant electronic couplings. Here, we explore how noncovalent interactions between molecules and surfaces stabilize intermolecular structures with strong singlet fission couplings. Using molecular dynamics simulations, we studied the aggregation patterns of tetracene molecules...

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