Electronic properties of simple thiocyanate species using synchrotron radiation

LUCAS S. RODRÍGUEZ PIRANI; MARIANA GERONÉS; MAURICIO F. ERBEN; REINALDO L. CAVASSO FILHO; ROSANA M. ROMANO; CARLOS O. DELLA VÉDOVA

Campinas

Otro; 21ª Reunião Anual de Usuários (RAU), Laboratório Nacional de Luz Síncrotron; 2011

As part of a more general project aimed to the study of the structural and spectroscopical properties of thiocyanate species, we have been investigated the photoionization processes and photodissociation channels of different compounds belonging to this family.1 The coalition of Photoelectron Spectroscopy (PES) and multicoincidence Time-Of-Flight (TOF)-based techniques seems to offer a most promising approach to a deeper understanding of the electronic structure and the ionic dissociation induced by photon absorption in the valence region. Furthermore, the development of a neon gas filter in the TGM line at the Brazilian Synchrotron National Laboratory (LNLS) now affords “pure” synchrotron radiation in the 12-21.5 eV range.2-4 Following this methodology, relatively simple species such as XC(O)SY (X= F, Cl and Y= Cl, CH3) have been studied.5-7 In this context, we report a study of the photon impact excitation and dissociation dynamics of CCl2FSCN molecule. HeI photoelectron spectrum has also been measured and the assignments were made with reference to the results of the SAC-CI/6-311+G*. Along with these valence shell studies, the inner-shell electronic properties have been investigated, most specifically around the sulfur 2p and chlorine 2p edges. Total Ion Yield spectra (TIY) and multicoincidence techniques, namely as Photoelectron-Photoion-Coincidence (PEPICO) and Photoelectron-Photoion- Photoion-Coincidence (PEPIPICO) time of flight (TOF) mass spectrometry were applied. The TIY spectra of CCl2FSCN following S 2p excitations is dominated by a group of five signals centered at 163.8, 165.3, 167.0, 167.9 and 168.6 eV, while the ionization edge is located at approximately 176.2 eV. In the Cl 2p region three signals can be observed, specially located at 199.8, 202.0 and 203.7 eV. PEPICO and PEPIPICO spectra were recorded on each resonance, and also below (typically 10 eV) and above (typically 50 eV) resonance bands. Possible fragmentations mechanisms are deduced from the interpretation of the PEPIPICO spectra.