Progress in synchrotron radiation technology has provided sources with high photon flux and energy resolution. Consequently, the more favorable conditions have stimulated experimental and theoretical studies of inner-shell ionization and excitation processes in small free molecules including highly diluted reactive species [1]. Fine spectral details revealed by using core-hole sub-natural lifetime resolution provide an insight into the photoabsorption and ionization energetics and dynamics. Results have been obtained for the first time on the C(1s) photoabsorption and dissociation processes of the CH3 free radical, produced in a supersonic jet, by total-ion-yield and 3D-ion momentum imaging spectroscopy. Due to the high photon energy resolution clear vibrational spectral details in electronic transitions involving a significant molecular geometry change have been obtained. Different photofragment patterns have also been observed depending on the nature of the selected core-excited resonance. Theoretical studies on the C(1s) photoabsorption spectrum of the CH3 radical, which explicitly includes vibrational effects accompanying the photoexcitation process, have been carried out and the comparison between experiment and theory allows a detail characterization of the potential energy surface for the lowest lying core-excited state. The first study of umbrella-like motion in inner-shell spectroscopy in the case of CH3 will be presented. The S(2p) photoabsorption and ionization processes in the CS transient molecule, produced by a MW plasma source, have been investigated. The fine spectral details obtained in this study allow the characterization of the vibronic structure and the potential energy curve of S(2p) core-excited and ionic states of the CS molecule. Experimental results have been crucially supported by ab initio relativistic calculations that provided a firm basis for the spectral assignment. Excellent agreement is found between experiment and theory. [1] S. Stranges, R. Richter, and M. Alagia, J. Chem. Phys., 116, 3676 (2002).
Inner-shell studies of free radical and transient species / Stranges, Stefano. - STAMPA. - (2005), pp. 32-32.
Inner-shell studies of free radical and transient species
STRANGES, Stefano
2005
Abstract
Progress in synchrotron radiation technology has provided sources with high photon flux and energy resolution. Consequently, the more favorable conditions have stimulated experimental and theoretical studies of inner-shell ionization and excitation processes in small free molecules including highly diluted reactive species [1]. Fine spectral details revealed by using core-hole sub-natural lifetime resolution provide an insight into the photoabsorption and ionization energetics and dynamics. Results have been obtained for the first time on the C(1s) photoabsorption and dissociation processes of the CH3 free radical, produced in a supersonic jet, by total-ion-yield and 3D-ion momentum imaging spectroscopy. Due to the high photon energy resolution clear vibrational spectral details in electronic transitions involving a significant molecular geometry change have been obtained. Different photofragment patterns have also been observed depending on the nature of the selected core-excited resonance. Theoretical studies on the C(1s) photoabsorption spectrum of the CH3 radical, which explicitly includes vibrational effects accompanying the photoexcitation process, have been carried out and the comparison between experiment and theory allows a detail characterization of the potential energy surface for the lowest lying core-excited state. The first study of umbrella-like motion in inner-shell spectroscopy in the case of CH3 will be presented. The S(2p) photoabsorption and ionization processes in the CS transient molecule, produced by a MW plasma source, have been investigated. The fine spectral details obtained in this study allow the characterization of the vibronic structure and the potential energy curve of S(2p) core-excited and ionic states of the CS molecule. Experimental results have been crucially supported by ab initio relativistic calculations that provided a firm basis for the spectral assignment. Excellent agreement is found between experiment and theory. [1] S. Stranges, R. Richter, and M. Alagia, J. Chem. Phys., 116, 3676 (2002).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
