2021 New's Items

Vibronic coupling in energy transfer dynamics and two-dimensional electronic–vibrational spectra

Arsenault EA
Schile AJ
Limmer DT
Fleming GR
2021

We introduce a heterodimer model in which multiple mechanisms of vibronic coupling and their impact on energy transfer can be explicitly studied. We consider vibronic coupling that arises through either Franck–Condon activity in which each site in the heterodimer has a local electron–phonon coupling or Herzberg–Teller activity in which the transition dipole moment coupling the sites has an explicit vibrational mode-dependence. We have computed two-dimensional electronic–vibrational (2DEV) spectra for this model while varying the magnitude of these two effects and find that 2DEV...

Two-dimensional electronic–vibrational spectroscopy: Exploring the interplay of electrons and nuclei in excited state molecular dynamics

Arsenault EA
Bhattacharyya P
Yoneda Y
Fleming GR
2021

Two-dimensional electronic–vibrational spectroscopy (2DEVS) is an emerging spectroscopic technique which exploits two different frequency ranges for the excitation (visible) and detection (infrared) axes of a 2D spectrum. In contrast to degenerate 2D techniques, such as 2D electronic or 2D infrared spectroscopy, the spectral features of a 2DEV spectrum report cross correlations between fluctuating electronic and vibrational energy gaps rather than autocorrelations as in the degenerate spectroscopies. The center line slope of the spectral features reports on this cross correlation...

Insights into Photosynthetic Energy Transfer Gained from Free-Energy Structure: Coherent Transport, Incoherent Hopping, and Vibrational Assistance Revisited

Ishizaki A
Fleming GR
2021

Giant strides in ultrashort laser pulse technology have enabled real-time observation of dynamical processes in complex molecular systems. Specifically, the discovery of oscillatory transients in the two-dimensional electronic spectra of photosynthetic systems stimulated a number of theoretical investigations exploring the possible physical mechanisms of the remarkable quantum efficiency of light harvesting processes. In this work, we revisit the elementary aspects of environment-induced fluctuations in the involved electronic energies and present a simple way to understand energy...

Electron–Nuclear Dynamics Accompanying Proton-Coupled Electron Transfer

Yoneda Y
Mora SJ
Shee J
Wadsworth BL
Arsenault EA
Hait D
Kodis G
Gust D
Moore GF
Moore AL
Head-Gordon M
Moore TA
Fleming GR
2021

Although photoinduced proton-coupled electron transfer (PCET) plays an essential role in photosynthesis, a full understanding of the mechanism is still lacking due to the complex nonequilibrium dynamics arising from the strongly coupled electronic and nuclear degrees of freedom. Here we report the photoinduced PCET dynamics of a biomimetic model system investigated by means of transient IR and two-dimensional electronic–vibrational (2DEV) spectroscopies, IR spectroelectrochemistry (IRSEC), and calculations utilizing long-range-corrected hybrid density functionals. This collective...

A DNA packaging motor inchworms along one strand allowing it to adapt to alternative double-helical structures

Castillo JP
Tong AB
Tafoya S
Jardine PJ
Bustamante C
2021

Ring ATPases that translocate disordered polymers possess lock-washer architectures that they impose on their substrates during transport via a hand-over-hand mechanism. Here, we investigate the operation of ring motors that transport ordered, helical substrates, such as the bacteriophage ϕ29 dsDNA packaging motor. This pentameric motor alternates between an ATP loading dwell and a hydrolysis burst wherein it packages one turn of DNA in four steps. When challenged with DNA-RNA hybrids and dsRNA, the motor matches its burst to the shorter helical...

Phase transition dynamics in one-dimensional halide perovskite crystals

Lai M
Lei T
Zhang Y
Jin J
Steele JA
Yang P
2021

Triiodide perovskites CsPbI3CsPbI3, CsSnI3...

Nanopore-mediated protein delivery enabling three-color single-molecule tracking in living cells

Chen Z
Cao Y
Lin C-W
Alvarez S
Oh D
Yang P
Groves JT
2021

Multicolor single-molecule tracking (SMT) provides a powerful tool to mechanistically probe molecular interactions in living cells. However, because of the limitations in the optical and chemical properties of currently available fluorophores and the multiprotein labeling strategies, intracellular multicolor SMT remains challenging for general research studies. Here, we introduce a practical method employing a nanopore-electroporation (NanoEP) technique to deliver multiple organic dye-labeled proteins into living cells for imaging. It can be easily expanded to three channels in...

Kinetics of moisture-induced phase transformation in inorganic halide perovskite

Lin Z
Zhang Y
Gao M
Steele JA
Louisia S
Yu S
Quan LN
Lin C-K
Limmer DT
Yang P
2021

The high-temperature (high-T) phase of cesium lead iodide (CsPbI3) presents great promise for photovoltaic applications; however, exposure to ambient moisture at room temperature transforms it into its less-desirable low-temperature (low-T) phase with a larger band gap. While there have been theoretical predictions on the influence of moisture level on the phase transformation kinetics, the corresponding quantitative experimental evidence has remained limited. Tracking CsPbI3 phase transformation under controlled relative humidity (RH), we find that rising RH increases the nucleation...

Sulfur-doped graphene anchoring of ultrafine Au25 nanoclusters for electrocatalysis

Li M
Zhang B
Cheng T
Yu S
Louisia S
Chen C
Chen S
Cestellos-Blanco S
Goddard WA
Yang P
2021

The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of stability. We demonstrate herein that chemical dopants on sulfur-doped graphene (S-G) can be utilized to stabilize ultrafine (sub-2 nm) Au25(PET)18 clusters to enable stable nitrogen reduction reaction (NRR) without significant structural degradation. The Au25@S-G exhibits an ammonia yield rate of 27.5μ...

Vibrational relaxation dynamics in layered perovskite quantum wells

Quan LN
Park Y
Guo P
Gao M
Jin J
Huang J
Copper JK
Schwartzberg A
Schaller R
Limmer DT
Yang P
2021

Organic-inorganic layered perovskites, or Ruddlesden-Popper perovskites, are two-dimensional quantum wells with layers of lead-halide octahedra stacked between organic ligand barriers. The combination of their dielectric confinement and ionic sublattice results in excitonic excitations with substantial binding energies that are strongly coupled to the surrounding soft, polar lattice. However, the ligand environment in layered perovskites can significantly alter their optical properties due to the complex dynamic disorder of the soft perovskite lattice. Here, we infer dynamic disorder...