On the ionization and dissociative photoionization of iodomethane: a definitive experimental enthalpy of formation of CH3I

Bodi, Andras; Shuman, Nicholas S.; Baer, Tomas

doi:10.1039/b915400k

Cited by 72 publications

(112 citation statements)

References 45 publications

Supporting

Mentioning

101

Contrasting

Order By: Relevance

“…Based on a previous study of Ar, N 2 , and CH 3 I, 22 the threshold photoelectron peak positions could be expected to be Stark shifted 23 by 5 meV to lower energy when applying the higher field. In the same study, 22 field effects were found not to play a role in off-resonance threshold photoionization, which suggests that autoionization can compete effectively with field ionization in the absence of long-lived Rydberg states. In C 2 F 4 + , the TPES peak positions did not shift measurably as a function of the field strength, indicating fast autoionization and neutral decay channels for high-n Rydberg states.…”

Section: A Experimentalmentioning

confidence: 98%

“…Furthermore, directC-state involvement is not necessarily required in threshold photoionization. In the CH 3 I study, 22 it was proposed that the neutral parent can be excited to the Rydberg manifold in the initial step. The Rydberg manifolds belonging to each ion state will have the similar characteristics to the ion state, and autoionization may also occur after internal conversion.…”

Section: F-atom Loss From C 2 H 3 Fmentioning

confidence: 99%

“…This explains why the nonstatistical F-loss channel is seen at slightly lower energies than the actualC-state peak in the photoelectron spectrum of C 2 H 3 F + . In the iodomethane study, 22 neutral dissociative states were proposed to connect different Rydberg manifolds with the corresponding ion states lying approximately 2 eV apart. In monofluoroethene, such neutral states do not need to be invoked, since the Rydberg manifolds themselves can readily interconvert at conical intersections.…”

Section: F-atom Loss From C 2 H 3 Fmentioning

confidence: 99%

See 2 more Smart Citations

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Harvey

Hemberger

Bodi

et al. 2013

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

Valence threshold photoelectron spectra of four fluorinated ethenes; C 2 H 3 F, 1,1-C 2 H 2 F 2 , C 2 HF 3 , and C 2 F 4 were recorded at the Swiss Light Source with 0.002 eV resolution. The adiabatic ionization energies were found to be 10.364 ± 0.007, 10.303 ± 0.005, 10.138 ± 0.007, and 10.110 ± 0.009 eV, respectively. The electronic ground state of each cation shows well-resolved multi-component vibrational progressions, the dominant transitions being in the C=C stretching mode. Density functional theory based Franck-Condon simulations are used to model the vibrational structure and assign the spectra, sometimes revising previous assignments. An additional vibrational progression in the first photoelectron band of 1,1-C 2 H 2 F 2 indicates that the ground electronic state of the molecular ion is no longer planar. It is shown that ab initio vibrational frequencies together with the observed vibrational spacings do not always suffice to assign the spectra. In addition to symmetry rules governing the transitions, it is often essential to consider the associated Franck-Condon factors explicitly. Ionization to higher lying excited valence electronic states were also recorded by threshold ionization up to 23 eV photon energy. Equation-of-motion coupled cluster with single and double substitutions for ionization potential (EOM-IP-CCSD/cc-pVTZ) calculations confirmed historic electronic state assignments, and untangled the ever more congested spectra with increasing F-substitution. Previous attempts at illuminating the intriguing dissociative photoionization mechanism of fluorinated ethenes are reconsidered in view of new computational and experimental results. We show how non-statistical F-atom loss from C 2 H 3 F + is decoupled from the ground state dissociation dynamics in the energy range of itsC state. Both the statistical and the non-statistical dissociation processes are mediated by a plethora of conical intersections.

show abstract

Section: A Experimentalmentioning

confidence: 98%

Section: F-atom Loss From C 2 H 3 Fmentioning

confidence: 99%

Section: F-atom Loss From C 2 H 3 Fmentioning

confidence: 99%

See 1 more Smart Citation

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Harvey

Hemberger

Bodi

et al. 2013

The Journal of Chemical Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is also essential when cooling the sample in a supersonic molecular beam, which generates a variety of clusters along with the cooled sample of interest. A recent example shown by Bodi at the conference (which may be the first of its kind) is shown in Figure 1 for the case of methyl iodide cooled in a seeded Ar beam [19]. The dominant species in the total TPES (solid points) is ascribed to the cold CH 3 I.…”

Section: A Synchrotron-based Vuv Threshold Photoelectron Spectroscopmentioning

confidence: 93%

Ion spectroscopy: Where did it come from; where is it now; and where is it going?

Baer¹,

Dunbar

2010

J. Am. Soc. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

a large group of mass spectrometrists working in the area of ion spectroscopy. In this introduction to the field, we provide a brief history, its current state, and where it is going. Ion spectroscopy of intermediate size molecules began with photoelectron spectroscopy in the 1960s, while electronic spectroscopy of ions using the photodissociation "action spectroscopic" mode became active in the next decade. These approaches remained for many years the main source of information about ionization energies, electronic states, and electronic transitions of ions. In recent years, highresolution laser techniques coupled with pulsed field ionization and sample cooling in molecular beams have provided high precision ionization energies and vibrational frequencies of small to intermediate sized molecules, including a number of radicals. More recently, optical parametric oscillator (OPO) IR lasers and free electron lasers have been developed and employed to record the IR spectra of molecular ions in either molecular beams or ion traps. These results, in combination with theoretical ab initio molecular orbital (MO) methods, are providing unprecedented structural and energetic information about gas-phase ions. (J Am Soc Mass Spectrom 2010, 21, 681-693) © 2010 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry T here are at least three perspectives guiding research in molecular spectroscopy of ions, which have given rise to rather distinct research communities. First is the goal of finding the quantum energy levels (electronic, vibrational, rotational) with high accuracy and energy resolution. Benefiting from experimental convenience, a vast body of results of this sort has been accumulated from photoionization and photoelectron spectroscopy experiments where the initial sample is the neutral molecule corresponding to an ion of interest.Second is the question of "what color" the ion is, that is to say, taking the ion itself as the sample, observing the wavelengths and transition intensities of the optical absorptions or emissions of the ion. These experiments are difficult, but have great interest for the study of ions found in nature, as for instance among the community of astronomers trying to sort out the telescope spectra corresponding to molecular species existing in extraterrestrial environments.Third is the use of spectra as a window to the identification and structural characterization of ionic molecules formed from interesting precursors by any of a variety of ionization, ion-molecule reaction, or ionextraction techniques. Combined with mass spectrometry, this branch of ion spectroscopy has developed into a new structural approach comparable to MS/MS, thanks to its ability to distinguish small conformational or structural differences among iso-mass ions. These studies have been dominated by the use of "action spectroscopy" (multi-photon and ion tagging dissociation techniques) to provide convenient, although indirect, access to the spectra of interesting ions.The three major parts of thi...

show abstract

“…Recent threshold photoelectron photoion coincidence (TPEPICO) experiments, in which both the photon and the photoelectron energies are known to within 1-2 meV (0.1-0.2 kJ mol -1 ), [1,[10][11][12] are capable of measuring dissociative photoionization onset energies in small to medium sized molecules with such levels of accuracy. To reiterate, in the absence of an overall reverse barrier, the onset energies, E 0 , correspond to the reaction energy at 0 K, and yield the enthalpies of formation for the parent ion, daughter ion or neutral fragment if two out of the three are known;…”

Section: Introductionmentioning

confidence: 99%

Fast Dissociations of Halogenated Methanes: A Thermochemical Network

Harvey

2013

Springer Theses

View full text Add to dashboard Cite

On the ionization and dissociative photoionization of iodomethane: a definitive experimental enthalpy of formation of CH3I

Cited by 72 publications

References 45 publications

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Vibrational and electronic excitations in fluorinated ethene cations from the ground up

Ion spectroscopy: Where did it come from; where is it now; and where is it going?

Fast Dissociations of Halogenated Methanes: A Thermochemical Network

Contact Info

Product

Resources

About