Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 111: Nanostructures at Surfaces: Molecular Systems III
O 111.1: Talk
Friday, March 24, 2017, 10:30–10:45, REC/PHY C213
Resolving molecular products of astro-photochemistry: light-induced hydrogenation of 1,2-bis(2-phenylethynyl)benzene — •Martin Svec1, Jack Hellerstedt1, Ales Cahlik1, Oleksandr Stetsovych1, Maria Moro Lagares1, Irena Stara2, Ivo Stary2, and Pavel Jelinek1 — 1Institute of Physics, CAS, Praha, CR — 2Institute of Chemistry and Biochemistry, CAS, Praha, CR
The interaction between photons and molecules is as enticing as it is elusive. Typically, light-induced reactions have complicated reaction pathways and a diverse range of products that are difficult to characterize with (liquid) solution based measurements. The advent of on-surface preparation and scanned probe measurement techniques has greatly advanced the ability to resolve complicated reactions by direct observation of structural and conformational changes. We extend this a step further by considering the possibility of reactions occurring in the dilute limit, e.g. high and ultrahigh vacuum (UHV) conditions, the nearest local approximation of the interstellar medium of our universe.
In this paradigmatic astro-photochemistry experiment, a dilute gas (in UHV) of phenyl-based molecules (1,2-bis(2-phenylethynyl)benzene) is exposed to high intensity UV light during deposition onto a single crystal metal substrate. The products are subsequently studied via low temperature (5K) scanning probe techniques capable of resolving molecular structure at the atomic level. We observe chemically altered products, assembled in geometrically distinct superstructures. Linear assemblies can exceed 250nm in length. These are identified using theoretical simulations and comparison with the AFM/STM data.