Broken Symmetry Optical Transitions in (6,5) Single-Walled Carbon Nanotubes Containing Defects Revealed by First-Principles Theory.

We present a first-principles many-body perturbation theory study of nitrophenyl-doped (6,5) single-walled nanotubes (SWCNTs) to understand how doping impacts the excitonic properties. -doped SWCNTs are promising as a class of optoelectronic materials with bright tunable photoluminescence, long spin coherence, and single-photon emission (SPE), motivating the study of spin excitations. We predict that the dopant results in a single unpaired spin localized around the defect site, which induces multiple low-energy excitonic peaks.

Long-lived electronic spin qubits in single-walled carbon nanotubes.

Electron spins in solid-state systems offer the promise of spin-based information processing devices. Single-walled carbon nanotubes (SWCNTs), an all-carbon one-dimensional material whose spin-free environment and weak spin-orbit coupling promise long spin coherence times, offer a diverse degree of freedom for extended range of functionality not available to bulk systems. A key requirement limiting spin qubit implementation in SWCNTs is disciplined confinement of isolated spins.

Multicolor polymeric carbon dots: synthesis, separation and polyamide-supported molecular fluorescence.

Multicolor carbon dots (CDs) have been developed recently and demonstrate great potential in bio-imaging, sensing, and LEDs. However, the fluorescence mechanism of their tunable colors is still under debate, and efficient separation methods are still challenging. Herein, we synthesized multicolor polymeric CDs through solvothermal treatment of citric acid and urea in formamide.

-Functionalization of Single-Walled Carbon Nanotubes Creates Localized Spins.

Chemical functionalization-introduced quantum defects in single-walled carbon nanotubes (SWCNTs) have shown compelling optical properties for their potential applications in quantum information science and bioimaging. Here, we utilize temperature- and power-dependent electron spin resonance measurements to study the fundamental spin properties of SWCNTs functionalized with well-controlled densities of quantum defects. Signatures of isolated spins that are highly localized at the defect sites are observed, which we further confirm with density functional theory calculations.

Accurate First-Principles Calculation of the Vibronic Spectrum of Stacked Perylene Tetracarboxylic Acid Diimides.

π-stacked organic electronic materials are tunable light absorbers with many potential applications in optoelectronics. The optical properties of such molecules are highly dependent on the nature and energy of electron-hole pairs or excitons formed upon light absorption, which in turn are determined by intra- and intermolecular electronic and vibrational excitations. Here, we present a first-principles approach for describing the optical spectrum of stacked organic molecules with strong vibronic coupling.

Sticking to (first) principles: quantum molecular dynamics and Bayesian probabilistic methods to simulate aquatic pollutant absorption spectra.

This work explores the relationship between theoretically predicted excitation energies and experimental molar absorption spectra as they pertain to environmental aquatic photochemistry. An overview of pertinent Quantum Chemical descriptions of sunlight-driven electronic transitions in organic pollutants is presented. Second, a combined molecular dynamics (MD), time-dependent density functional theory (TD-DFT) analysis of the ultraviolet to visible (UV-Vis) absorption spectra of six model organic compounds is presented alongside accurate experimental data.