Mass spectrometry study of the fragmentation of valence and core-shell (Cl 2p) excited CHCl3 and CDCl3 molecules.

The dissociative photoionization of the chloroform and chloroform-d molecules has been studied in the valence region and around the chlorine 2p edge. Time-of-flight mass spectrometry in the coincidence mode-namely, photoelectron-photoion coincidence (PEPICO)-was employed. He I lamp and tunable synchrotron radiation were used as light sources. Total and partial ion yields have been recorded as a function of the photon energy. Singly, doubly, and triply ionized species have been observed below (195 eV), on (201 eV), and above (230 eV) the Cl 2p resonances. A definite degree of site-selective fragmentation was observed at the Cl 2p resonance as the relative contributions of several ionic species were seen to go through a maximum at 201 eV. At the same time all stable doubly charged ions were also observed at 198 eV (below the 2p resonances), resulting from direct ionization processes. Isotopic substitution is shown to provide a very efficient means of improving the mass resolution and assignment of unresolved peaks in spectra of CHCl(3), particularly for those fragments differing by a hydrogen atom. It is suggested that ultrafast fragmentation of the system following 2p excitation to a strongly antibonding state contributes to the large amount of Cl(+) observed in the PEPICO spectrum measured at 201 eV. Kinetic energy distributions were determined for the H(+), D(+), and Cl(+) fragments.

[1]  A. C. F. Santos,et al.  A multi-coincidence study of the double, triple photoionization and fragmentation of the SiF4 molecule around the Si 2p edge , 2002 .

[2]  O. Björneholm.  Direct and indirect methods for studying the energetics and dynamics of the Auger Doppler effect in femtosecond ultra-fast dissociation , 2001 .

[3]  A. C. A. Santos,et al.  Fragmentação de moléculas pela luz síncrotron e por elétrons rápidos. I. O caso do halotano, C2F3HClBr , 2001 .

[4]  A. C. F. Santos,et al.  Dissociative photoionization of SiF4 around the Si 2p edge: a new TOFMS study with improved mass resolution , 2001 .

[5]  F. Castaño,et al.  Nascent kinetic energy distributions of the ions produced by electron-impact on the CH3F molecule , 2000 .

[6]  D. Kim,et al.  Photodissociation dynamics of the propargyl bromide molecular ion , 2000 .

[7]  R. Grant,et al.  An experimental and computational study of the double ionization of CH3Cl, CH2Cl2, and CHCl3 molecules to singlet and triplet electronic states of their dications , 1999 .

[8]  O. Björneholm,et al.  Femtosecond dissociation dynamics of core-excited molecular water , 1999 .

[9]  O. Gessner,et al.  RESONANT PHOTOFRAGMENTATION OF WATER AT THE OXYGEN K EDGE BY HIGH-RESOLUTION ION-YIELD SPECTROSCOPY , 1999 .

[10]  M. Simon,et al.  SITE-SELECTIVE PHOTOCHEMISTRY OF CORE EXCITED MOLECULES : ROLE OF THE INTERNAL ENERGY , 1998 .

[11]  K. Leung,et al.  Neutral Dissociation of Hydrogen Following Photoexcitation of HCl at the Chlorine K Edge , 1998 .

[12]  D. Mathur,et al.  An experimental and theoretical study of the dissociative ionization of and by an intense laser field , 1997 .

[13]  E. Morikawa,et al.  A new time-of-flight mass spectrometer for electron-ion and ion-ion coincidence experiments (PEPICO, PIPICO and PEPIPICO) , 1997 .

[14]  Ying Jf,et al.  Electron-impact excitation of low-lying preionization-edge electronic and Rydberg transitions of fluoroform and chloroform: Bethe surfaces and absolute generalized oscillator strengths. , 1996 .

[15]  R. Thissen,et al.  Fragmentation of methyl chloride photoexcited near Cl (2p) by mass spectrometry , 1994 .

[16]  C. Reynaud,et al.  Site‐selective fragmentation in core‐excited bromo‐chloro‐alkanes [Br(CH2)nCl] , 1994 .

[17]  I. Nenner,et al.  Multicoincidence mass spectrometry applied to hexamethyldisilane excited around the silicon 2p edge , 1993 .

[18]  M. Simon,et al.  A photoelectron-ion multiple coincidence technique applied to core ionization of molecules , 1991 .

[19]  D. M. Hanson.  Chemistry Induced by Core Electron Excitation , 2007 .

[20]  J. Eland.  The dynamics of three-body dissociations of dications studied by the triple coincidence technique PEPIPICO , 1987 .

[21]  M. Suto,et al.  Fluorescence yields from photodissociative excitation of chloromethanes by vacuum ultraviolet radiation , 1987 .

[22]  J. Beynon,et al.  Multiple ionization, charge separation and charge stripping reactions involving polycyclic aromatic compounds , 1985 .

[23]  James W. Taylor,et al.  Angle-resolved photoelectron spectroscopy of the chloro-substituted methanes☆ , 1983 .

[24]  W. Niessen,et al.  30.4 nm He (II) photoelectron spectra of organic molecules Part VI. Halogeno-compounds (C, H, X; X = Cl, Br, I)☆ , 1982 .

[25]  M. Thompson,et al.  Auger electron spectra and chemical shifts of the chloromethanes , 1978 .

[26]  C. E. Brion,et al.  Inner-shell excitation and EXAFS-type phenomena in the chloromethanes , 1978 .

[27]  I. Mclaren,et al.  TIME-OF-FLIGHT MASS SPECTROMETER WITH IMPROVED RESOLUTION , 1955 .