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DNA photoprotection

Femtosecond Dynamics in the Photoprotection in Thymine Brian McFarland and the LCLS Nucleobase Photoprotection collaboration. UV Excitation . Photoprotection. X-Ray Probe. Motivation:. Experiment:. p*. Auger. p → p *. n → p. DNA photoprotection. IP.

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DNA photoprotection

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  1. Femtosecond Dynamics in the Photoprotection in Thymine Brian McFarland and the LCLS NucleobasePhotoprotectioncollaboration UV Excitation Photoprotection X-Ray Probe Motivation: Experiment: p* Auger p →p* • n → p DNA photoprotection IP • Strong absorption in the UV • Photo excited states reactive: • How does the molecule survive? • Predicted non-Born-Oppenheimer • relaxation: 100 fs? Several ps? • New approach gives spatial/orbital • sensitivity Auger Matrix Element: n Time Delay Δt? Valence and core overlap give site and orbital selectivity X-ray pulse p O1s Results: Future: Time dependent X-Ray Absorption and Emission Measurements n orbital contributions Pump ON – Pump OFF Pump ON+Pump OFF Time Independent NEXAFS: ALS BL8 528 530 532 534 536 538 540 Excitation Tunable X-Ray Probe Photon Energy (eV) Core 1 2 3 490 500 510 520 530 540 Electron Kinetic Energy (eV) Capabilities: • Tunable/Selectable Photon Energy: Monochrometer/Seeded FEL. • Desired Resolution: < 0.5 eV • Other DNA bases/ Gas phase samples • Liquid samples/environments

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