Phys Chem/Chem Phys Seminar

Abstract:  Many of the new molecules discovered in astrophysical objects are totally outlandish by traditional perspectives: long linear unsaturated carbon chains, metals in surprising charge states, and strained ring structures have all challenged chemists to think beyond terrestrial conventions in explaining how these molecules form and react, and where they fit into the overall cycle of planetary and stellar evolution.

Abstract: Biogenic emissions contribute significantly to the composition and chemistry of the troposphere, with vegetation being the main source of volatile alkenes. For example, isoprene is emitted by plants during photosynthesis and is one of the most abundant organic compounds released into the atmosphere: around 500 Tg of isoprene is emitted annually and forms the largest fraction of non-methane hydrocarbon emissions. The dominant mechanisms for the atmospheric removal of alkenes are reactions with the OH radical and ozone.

Abstract: Short-range-interacting particles can in principle crystallize via so-called non-classical pathways invoking a metastable liquid intermediate, yet non-equilibrium gelation often occurs before a metastable liquid can form. Using in situ X-ray scattering, we nevertheless watch electrostatically stabilized colloidal semiconducting nanocrystals self-assemble into long-range-ordered superlattices via this non-classical pathway and show how the pathway increases the rate of crystallization over that of direct crystallization from the colloidal phase.

Abstract:  I present evidence that electron-transfer in model organic photovoltaic blends can be modeled as a competition between short and long-range electron transfer events, each described by a Marcus parabola having different reorganization energies for the most localized charge-transfer (CT) state and the mobile free charge (CT) state.

Abstract: Atomically thin van der Waals crystals like graphene and transition metal dichalcogenides allow for the creation of arbitrary, atomically precise heterostructures simply by stacking disparate monolayers without the constraints of covalent bonding or epitaxy. While these are commonly described as nanoscale LEGO blocks, many intriguing phenomena have been discovered in the recent past that go beyond this simple analogy.

Abstract: Polydopamine (PDA) is a widely employed anchoring layer across various applications. Despite its straightforward preparation, PDA's utility is restricted due to its notable chemical and topological variability. Understanding the formation process and physicochemical characteristics of the formed confluent layers, as well as the present adherent nanoaggregates [1 – 3], on a nanoscale level is essential for expanding the applications of PDA.

Abstract: Photosystems are protein complexes located in the thylakoid membranes of plants and other organisms and are the sites of the fundamental first steps of photosynthesis. In particular, Photosystem II (PSII) absorbs solar energy to catalyze the oxidation of water, generating oxygen as a byproduct. The photocatalytic reaction in PSII also initiates an electron transport chain and proton gradient, that results in the production of NADPH and ATP molecules.