98206-68-9Relevant academic research and scientific papers
Photodissociation Dynamics of Cyclopropenylidene, c-C3H2
Schuurman, Michael S.,Giegerich, Jens,Pachner, Kai,Lang, Daniel,Kiendl, Benjamin,MacDonell, Ryan J.,Krueger, Anke,Fischer, Ingo
, p. 14486 - 14495 (2015)
In this joint experimental and theoretical study we characterize the complete dynamical "life cycle" associated with the photoexcitation of the singlet carbene cyclopropenylidene to the lowest lying optically bright excited electronic state: from the initial creation of an excited-state wavepacket to the ultimate fragmentation of the molecule on the vibrationally hot ground electronic state. Cyclopropenylidene is prepared in this work using an improved synthetic pathway for the preparation of the precursor quadricyclane, thereby greatly simplifying the assignment of the molecular origin of the measured photofragments. The excitation process and subsequent non-adiabatic dynamics have been previously investigated employing time-resolved photoelectron spectroscopy and are now complemented with high-level ab initio trajectory simulations that elucidate the specific vibronic relaxation pathways. Lastly, the fragmentation channels accessed by the molecule following internal conversion are probed using velocity map imaging (VMI) so that the identity of the fragmentation products and their corresponding energy distributions can be definitively assigned.
On the absolute photoionization cross section and dissociative photoionization of cyclopropenylidene
Holzmeier, Fabian,Fischer, Ingo,Kiendl, Benjamin,Krueger, Anke,Bodi, Andras,Hemberger, Patrick
, p. 9240 - 9247 (2016/04/09)
We report the determination of the absolute photoionization cross section of cyclopropenylidene, c-C3H2, and the heat of formation of the C3H radical and ion derived by the dissociative ionization of the carbene. Vacuum ultraviolet (VUV) synchrotron radiation as provided by the Swiss Light Source and imaging photoelectron photoion coincidence (iPEPICO) were employed. Cyclopropenylidene was generated by pyrolysis of a quadricyclane precursor in a 1 : 1 ratio with benzene, which enabled us to derive the carbene's near threshold absolute photoionization cross section from the photoionization yield of the two pyrolysis products and the known cross section of benzene. The cross section at 9.5 eV, for example, was determined to be 4.5 ± 1.4 Mb. Upon dissociative ionization the carbene decomposes by hydrogen atom loss to the linear isomer of C3H+. The appearance energy for this process was determined to be AE0K(c-C3H2; l-C3H+) = 13.67 ± 0.10 eV. The heat of formation of neutral and cationic C3H was derived from this value via a thermochemical cycle as ΔfH0K(C3H) = 725 ± 25 kJ mol-1 and ΔfH0K(C3H+) = 1604 ± 19 kJ mol-1, using a previously reported ionization energy of C3H.
