Threshold Photoelectron−Photoion Coincidence Spectroscopy:  Dissociation Dynamics and Thermochemistry of Ge(CH3)4, Ge(CH3)3Cl, and Ge(CH3)3Br

Dávalos, Juan Z.; Koizumi, Hideya; Baer, Tomas

doi:10.1021/jp060264t

Cited by 11 publications

(9 citation statements)

References 44 publications

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“…It is, thus, possible, to decelerate ions and introduce a second field-free drift region at a lower potential, which can be used to distinguish daughter ions formed in slow dissociation reactions in the first field-free region. 34…”

Section: In Ref 33͒mentioning

confidence: 99%

Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

Bodi

Johnson²,

Gerber³

et al. 2009

Review of Scientific Instruments

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231

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An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm(-1) field, which enables the direct measurement of rate constants in the 10(3)-10(7) s(-1) range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

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Section: In Ref 33͒mentioning

confidence: 99%

Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

Bodi

Johnson²,

Gerber³

et al. 2009

Review of Scientific Instruments

Self Cite

199

231

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“…Over the last decade, we have successfully used this program to analyze PEPICO experimental data of the following systems: Simple dissociation C 10 H 15 Cl (chloroadamantane),46 Cp 2 Mn,47 CHCl 2 F,22 (CH 3 ) 2 CO, (CH 3 CO) 2 ,48 t ‐C 4 H 9 NC,49 i ‐C 3 H 7 Br, i ‐C 3 H 7 I,50 CH 2 I 2 , CH 2 Cl 2 , CH 2 Br 2 ,51 C 2 H 3 Br,52 CHCl 3 ,53, 54 (CH 3 ) 3 SiI, (CH 3 ) 4 Si,55 Ge(CH 3 ) 4 ,56 CH 3 NH 2 , C 2 H 5 NH 2 , C 3 H 7 NH 2 , C 4 H 9 NH 2 , i ‐C 4 H 9 NH 2 ,57 (CH 3 ) 3 N, (CH 3 ) 2 NH, (CH 3 )NH 2 ,58 1‐C 4 H 9 I,59 H 2 PC 2 H 5 ,60 CHBr 3 ,54 C 2 H 3 I,61 3‐Cl‐C 3 H 5 , 2‐Cl‐C 3 H 5 ,28 SiCl 4 , SiHCl 3 , SiCl 3 CH 3 , SiCl 3 CH 2 Cl,27 As(CH 3 ) 3 , Sb(CH 3 ) 3 , Bi(CH 3 ) 3 ,26 C 6 H 5 Cl, C 6 H 5 Br, C 6 H 5 I,25 CH 4 ,35 CH 3 I,36 t ‐C 4 H 9 I, t ‐C 4 H 9 OOH,24 C 2 H 5 Br, C 2 H 5 I,29 SCl 2 , SO 2 Cl 2 62 Parallel dissociations ICH 2 CN,63 C 3 H 4 O (acrolein),64 (C 6 H 5 ) 3 COH,65 CH 2 BrI, CH 2 ICl, CH 2 Cl 2 , CH 2 ClBr,51 C 2 H 5 COCH 3 , C 2 H 5 COCOCH 3 ,66 P(CH 3 ) 3 ,67 Ge(CH 3 ) 3 Cl, Ge(CH 3 ) 3 Br,56 neo ‐C 5 H 11 NH 2 ,68 CHCl 2 Br, CHClBr 2 ,54 C 2 H 3 Cl,61 C 3 H 6 ,28 Si 2 Cl 6 , SiCl 3 C 2 H 5 , SiCl 3 C 2 H 3 ,27 (CH 3 ) 4 C,24 t ‐C 4 H 9 OO t ‐C 4 H 9 , t ‐C 4 H 9 NN t ‐C 4 H 9 ,23 (CH 3 ) 2 NNH 2 ,30 Cp 2 Ni, Cp 2 Co, Cp 2 Cr 31 Consecutive dissociations CpCo(CO) 2 ,69 CpMn(CO) 3 ,70 BzCr(CO) 3 ,71 Bz 2 Cr,72 Co(CO) 2 NOP(CH 3 ) 3 , Co(CO) 2 NOP(C 2 H 5 ) 3 ,73 CpMn(CO) 2 CS, CpMn(CO) 2 CSe,74 C 2 H 3 Br 3 ,52 (CH 3 ) 6 Si 2 , (CH 3 ) 3 SiBr,55 HP(C 2 H 5 ) 2 ,60 t ‐C 4 H 9 NCCo(CO) 2 NO,75 S 2 Cl 2 , SOCl 2 62…”

Section: Introductionmentioning

confidence: 99%

“…C 10 H 15 Cl (chloroadamantane),46 Cp 2 Mn,47 CHCl 2 F,22 (CH 3 ) 2 CO, (CH 3 CO) 2 ,48 t ‐C 4 H 9 NC,49 i ‐C 3 H 7 Br, i ‐C 3 H 7 I,50 CH 2 I 2 , CH 2 Cl 2 , CH 2 Br 2 ,51 C 2 H 3 Br,52 CHCl 3 ,53, 54 (CH 3 ) 3 SiI, (CH 3 ) 4 Si,55 Ge(CH 3 ) 4 ,56 CH 3 NH 2 , C 2 H 5 NH 2 , C 3 H 7 NH 2 , C 4 H 9 NH 2 , i ‐C 4 H 9 NH 2 ,57 (CH 3 ) 3 N, (CH 3 ) 2 NH, (CH 3 )NH 2 ,58 1‐C 4 H 9 I,59 H 2 PC 2 H 5 ,60 CHBr 3 ,54 C 2 H 3 I,61 3‐Cl‐C 3 H 5 , 2‐Cl‐C 3 H 5 ,28 SiCl 4 , SiHCl 3 , SiCl 3 CH 3 , SiCl 3 CH 2 Cl,27 As(CH 3 ) 3 , Sb(CH 3 ) 3 , Bi(CH 3 ) 3 ,26 C 6 H 5 Cl, C 6 H 5 Br, C 6 H 5 I,25 CH 4 ,35 CH 3 I,36 t ‐C 4 H 9 I, t ‐C 4 H 9 OOH,24 C 2 H 5 Br, C 2 H 5 I,29 SCl 2 , SO 2 Cl 2 62…”

Section: Introductionmentioning

confidence: 99%

“…ICH 2 CN,63 C 3 H 4 O (acrolein),64 (C 6 H 5 ) 3 COH,65 CH 2 BrI, CH 2 ICl, CH 2 Cl 2 , CH 2 ClBr,51 C 2 H 5 COCH 3 , C 2 H 5 COCOCH 3 ,66 P(CH 3 ) 3 ,67 Ge(CH 3 ) 3 Cl, Ge(CH 3 ) 3 Br,56 neo ‐C 5 H 11 NH 2 ,68 CHCl 2 Br, CHClBr 2 ,54 C 2 H 3 Cl,61 C 3 H 6 ,28 Si 2 Cl 6 , SiCl 3 C 2 H 5 , SiCl 3 C 2 H 3 ,27 (CH 3 ) 4 C,24 t ‐C 4 H 9 OO t ‐C 4 H 9 , t ‐C 4 H 9 NN t ‐C 4 H 9 ,23 (CH 3 ) 2 NNH 2 ,30 Cp 2 Ni, Cp 2 Co, Cp 2 Cr 31…”

Section: Introductionmentioning

confidence: 99%

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Modeling unimolecular reactions in photoelectron photoion coincidence experiments

2010

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A computer program has been developed to model and analyze the data from photoelectron photoion coincidence (PEPICO) spectroscopy experiments. This code has been used during the past 12 years to extract thermochemical and kinetics information for almost a hundred systems, and the results have been published in over forty papers. It models the dissociative photoionization process in the threshold PEPICO experiment by calculating the thermal energy distribution of the neutral molecule, the energy distribution of the molecular ion as a function of the photon energy, and the resolution of the experiment. Parallel or consecutive dissociation paths of the molecular ion and also of the resulting fragment ions are modeled to reproduce the experimental breakdown curves and time-of-flight distributions. The latter are used to extract the experimental dissociation rates. For slow dissociations, either the quasi-exponential fragment peak shapes or, when the mass resolution is insufficient to model the peak shapes explicitly, the center of mass of the peaks can be used to obtain the rate constants. The internal energy distribution of the fragment ions is calculated from the densities of states using the microcanonical formalism to describe consecutive dissociations. Dissociation rates can be calculated by the RRKM, SSACM or VTST rate theories, and can include tunneling effects, as well. Isomerization of the dissociating ions can also be considered using analytical formulae for the dissociation rates either from the original or the isomer ions. The program can optimize the various input parameters to find a good fit to the experimental data, using the downhill simplex algorithm.

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“…On the other hand, the stability of the parent ion increases considerably among the silicon analogues, in which all of the Si(CH 3 ) 3 X + ions are stable. 35,36 This trend continues up to germanium, 37,38 and tin, which is the subject of this study.…”

Section: Introductionmentioning

confidence: 89%

Dissociation of energy selected Sn(CH3)4+, Sn(CH3)3Cl+, and Sn(CH3)3Br+ ions: evidence for isolated excited state dynamics

Baer

Guerrero

Dávalos

et al. 2011

Phys. Chem. Chem. Phys.

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The dissociation dynamics of Sn(CH 3 ) 4 + , Sn(CH 3 ) 3 Cl + , and Sn(CH 3 ) 3 Br + were investigated by threshold photoelectron photoion spectrometry using an electron imaging apparatus (iPEPICO) at the Swiss Light Source. The tetramethyltin ion was found to dissociate via Sn(CH 3 ) 4 + -Sn(CH 3 ) 3 + + CH 3 -Sn(CH 3 ) 2 + + 2 CH 3 , while the trimethyltin halide ions dissociated via methyl loss at low energies, and a competitive halogen loss at somewhat higher energies. The 0 K methyl loss onset for the three ions was found to be 9.410 AE 0.020 eV, 10.058 AE 0.020 eV, and 9.961 AE 0.020 eV, respectively. Statistical theory could not reproduce the observed onsets for the halogen loss steps in the halotrimethyltin ions. The halide loss signal as a function energy mimicked the excited state threshold photoelectron spectrum, from which we conclude that the halide loss from these ions takes place on an isolated excited state potential energy surface, which we describe by time dependent density functional calculations.The sequential loss of a second methyl group in the Sn(CH 3 ) 4 + ion, observed at about 3 eV higher energies than the first one, is also partially non-statistical. The derived product energy distribution resulting from the loss of the first methyl group is two-component with about 50% being statistical and the remainder associated with high translational energy products that peak at 2 eV. Time dependent DFT calculations show that a dissociative B ˜state lies in the vicinity of the experimental measurements. We thus propose that 50% of the Sn(CH 3 ) 4 + ions produced in this energy range internally convert to the X ˜state, on which they dissociate statistically, while the remainder dissociate directly from the repulsive B ˜state leading to high kinetic energy products.

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Threshold Photoelectron−Photoion Coincidence Spectroscopy: Dissociation Dynamics and Thermochemistry of Ge(CH₃)₄, Ge(CH₃)₃Cl, and Ge(CH₃)₃Br

Cited by 11 publications

References 44 publications

Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

Modeling unimolecular reactions in photoelectron photoion coincidence experiments

Dissociation of energy selected Sn(CH3)4+, Sn(CH3)3Cl+, and Sn(CH3)3Br+ ions: evidence for isolated excited state dynamics

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