Abstract:
Over the last decade, ice-coated interstellar nanoparticles emerged as molecular factories in the synthesis of complex, often biorelevant organics in cold molecular clouds and in star-forming regions. An intimate understanding of the fundamental reaction mechanisms generating these nanoparticles along with complex organics on their surfaces in deep space requires new knowledge not only on fundamental gas-phase reaction pathways to carbonaceous nanostructures, but also on the processing of low temperature ices by (non)ionizing radiation present even deep inside cold molecular clouds.
This talk provides an overview on recent advances in gas phase molecular beams studies and novel surface science experiments of particular importance. These studies are aimed to decipher the underlying reaction dynamics and kinetics leading to polycyclic aromatic hydrocarbons (PAHs) as fundamental molecular building blocks and precursors to carbonaceous nanoparticles (gas phase) and to complex organics (surface science) in deep space, many of which should not exist according to classical textbook knowledge. Novel developments focus on isomer selective vacuum ultraviolet photoionization (PI) techniques coupled with reflectron time-of-flight mass spectrometry (ReTOF-MS) exploiting single photon ionization in combination with the detection of functional groups via infrared spectroscopy (FTIR) with vacuum ultraviolet light generated by four-wave mixing and from synchrotrons. Facile low-temperature routes to complex aromatics signify a fundamental shift in the perception that aromatics can be only formed under high-temperature conditions on electronic ground state surfaces with novel mechanisms comprising excited state dynamics, submerged barriers, and unconventional concerted reactions between aromatic radicals. An outlook is also presented on condensed phase ultrafast spectroscopies and the exploration of growth processes on surfaces of carbonaceous particles levitated in ultrasonic fields are highlighted ultimately revealing the exotic chemistries of the carbonaceous universe we live in.
Biography:
Ralf I. Kaiser received his Ph.D. in Chemistry from the University of Münster and Nuclear Research Center Jülich (Germany) in 1994 and conducted postdoctoral work at UC Berkeley (Department of Chemistry). During 1997−2000, he performed his Habilitation at the Department of Physics (University Chemnitz, Germany) and Institute of Atomic and Molecular Sciences (Academia Sinica, Taiwan). He joined the Department of Chemistry at the University of Hawai’i in 2002, where he is currently Professor of Physical Chemistry and Director of the W. M. Keck Research Laboratory in Astrochemistry. His research focusses on Reaction Dynamics & Materials in Extreme Environments spanning Astrochemistry & Astrobiology, Combustion & Energy, Material Sciences & Propellants, Reaction Dynamics & Kinetics along with Planetary Sciences. These findings have been published so far in some 620 peer-refereed publications with an overall H-index of 72 and some 20,000 citations. For his research achievements, Ralf I. Kaiser was elected Fellow of the Royal Astronomical Society (UK), the Royal Society of Chemistry (UK), the Institute of Physics (UK), the American Physical Society (APS), the American Association for the Advancement of Science (AAAS), and of the American Chemical Society (ACS).
Seminar Series by the NYU-ECNU Center for Computational Chemistry at NYU Shanghai
This event is open to the NYU Shanghai, NYU, ECNU community and the computational chemistry community.