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3. Vibrational spectroscopy of reactive molecules and their high-temperature reaction products

Author

Constantinidis, Philipp

Subjects
Schwingungsspektroskopie, Bimolekulare Reaktion, Freie-Elektronen-Laser, Fotoionisation, ddc:540, Polycyclische Aromaten
Abstract

Schwingungsspektroskopie ist eine vielseitige spektroskopische Methode, mit der Molekülstrukturen und inter-/intramolekulare Wechselwirkungen untersucht werden können. Sie ist deshalb ein hervorragendes Mittel für die Identifikation von Molekülen. Die vorliegende Arbeit umfasst drei Projekte, in denen Schwingungsspektroskopie angewandt wurde, um reaktive Moleküle und ihre Hochtemperatur-Reaktionsprodukte zu untersuchen: 1. Die Aufklärung der Entstehungsmechanismen von polycyclischen aromatischen Kohlenwasserstoffen (PAKs) in Verbrennungsprozessen ist eines der Hauptanliegen der Verbrennungschemie. In der vorliegenden Arbeit wurde IR/UV-Ion-Dip-Spektroskopie in Verbindung mit DFT-Frequenzrechnungen und FTIR-Messungen angewandt, um Produkte von Radikal-Radikal-Reaktionen in einem Mikroreaktor bei hohen Temperaturen zu identifizieren. Als IR-Laserquelle für die IR/UV-Ion-Dip-Experimente diente der Freie-Elektronen-Laser FELIX (Free-Electron Laser for Infrared eXperiments) in Nijmegen (Niederlande). In einem Teilprojekt wurde der A 1A´ (S1), Vibrational spectroscopy is a versatile spectroscopic technique for the investigation of the molecular structure and inter-/intramolecular interactions. Therefore it is an excellent means for their identification. The present work comprises three projects, in which vibrational spectroscopy was applied to study reactive molecules and their high-temperature reaction products: 1. The elucidation of the mechanisms of polycyclic aromatic hydrocarbon (PAH) formation in combustion processes is one of the main topics of combustion chemistry. In the present work IR/UV ion dip spectroscopy in combination with DFT frequency computations and FTIR measurements was applied to identify the products of radical-radical reactions in a heated micro-reactor. The free-electron laser FELIX (Free-Electron Laser for Infrared eXperiments) in Nijmegen (the Netherlands) served as the IR laser source for the IR/UV ion dip experiments. As part of the project the A 1A´ (S1)

Published
2019

9. Hochgespannte Heterocyclen, gebildet aus Bor‐Bor‐Mehrfachbindungen und höheren Homologen der Chalcogene

Author

Braunschweig, Holger, primary, Constantinidis, Philipp, additional, Dellermann, Theresa, additional, Ewing, William C., additional, Fischer, Ingo, additional, Hess, Merlin, additional, Knight, Fergus R., additional, Rempel, Anna, additional, Schneider, Christoph, additional, Ullrich, Stefan, additional, Vargas, Alfredo, additional, and Woollins, J. Derek, additional

Published
2016
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10. Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens

Author

Braunschweig, Holger, primary, Constantinidis, Philipp, additional, Dellermann, Theresa, additional, Ewing, William C., additional, Fischer, Ingo, additional, Hess, Merlin, additional, Knight, Fergus R., additional, Rempel, Anna, additional, Schneider, Christoph, additional, Ullrich, Stefan, additional, Vargas, Alfredo, additional, and Woollins, J. Derek, additional

Published
2016
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13. Experimental Assessment of the Strengths of B–B Triple Bonds

Author

Böhnke, Julian, primary, Braunschweig, Holger, additional, Constantinidis, Philipp, additional, Dellermann, Theresa, additional, Ewing, William C., additional, Fischer, Ingo, additional, Hammond, Kai, additional, Hupp, Florian, additional, Mies, Jan, additional, Schmitt, Hans-Christian, additional, and Vargas, Alfredo, additional

Published
2015
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16. Formation of Coordination Polymers and Complexes at Room Temperature from Thiazole and Lanthanide-trichlorides.

Author

Dannenbauer, Nicole, Constantinidis, Philipp, Fischer, Ingo, and Müller‐Buschbaum, Klaus

Subjects
*POLYMERS, *RARE earth metals, *CHEMICAL bonds, *INTERMOLECULAR forces, *X-ray diffraction
Abstract

Seven lanthanide containing strand-like coordination polymers and dimeric complexes were obtained in a reversible reaction from 1, 3-thiazole (thz) and LnCl3 ( Ln = La, Ce, Pr, Nd). The reactions do not require activation and render coordination polymers accessible at room temperature, already. The product constitutions depend on the lanthanide and the thiazole-to-halide ratio. For lanthanum and cerium formation of the coordination polymers 1∞[ LnCl3(thz)3] ·thz as well as dimeric complexes [ Ln2Cl6(thz)8] ·3thz were observed. For praseodymium and neodymium dimeric complexes were observed with and without non-coordinating thz. Upon heating, the compounds release thiazole under re-formation of LnCl3, the formation reaction thus being a thermally reversible reaction. Compounds and conversion processes were characterized by temperature dependent X-ray powder and single-crystal X-ray diffraction, in-situ temperature dependent gas phase IR spectroscopy, DTA/TG, and elemental analysis. [ABSTRACT FROM AUTHOR]

Published
2015
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17. ElectronicSpectroscopy of 1-(Phenylethynyl)naphthalene.

Author

Constantinidis, Philipp, Lang, Melanie, Herterich, Jörg, Fischer, Ingo, Auerswald, Johannes, and Krueger, Anke

Subjects
*ELECTRONIC spectra, *NAPHTHALENE, *DIMERIZATION, *RADICALS (Chemistry), *HYDROCARBON analysis, *SPECTROMETRY
Abstract

Recently 1-(phenylethynyl)naphthalene(1-PEN) was suggested tobe the primary dimerization product of phenylpropargyl radicals andtherefore an important polycyclic hydrocarbon in combustion processes.Here we describe a spectroscopic investigation of a genuine 1-PENsample by several complementary techniques, infrared spectroscopy,multiphoton ionization (MPI), and threshold photoelectron spectroscopy.The infrared spectrum recorded in a gas cell confirms that 1-PEN isindeed the previously observed dimerization product of phenylpropargyl.The origin of the transition into the electronically excited S1state lies at 30823 cm–1, as found by MPI.Considerable vibrational activity is observed, and a number of low-wavenumberbands are assigned to a progression in the torsional motion. Valuesof 6 cm–1(S0) and 17 cm–1(S1) were derived for the fundamental of the torsion.In the investigated energy range the excited state lifetimes are inthe nanosecond range. Spectra of the 1-PEN/Ar cluster exhibit a redshift of the electronic origin of 22 cm–1, in goodagreement with other aromatic molecules. A threshold photoelectronspectrum recorded using synchrotron radiation yields an ionizationenergy of 7.58 eV for 1-PEN. An excited electronic state of the cationis found at 7.76 eV, and dissociative photoionization does not setin below 15 eV. [ABSTRACT FROM AUTHOR]

Published
2014
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