Sequential and concerted C–C and C–O bond dissociation in the Coulomb explosion of 2-propanol (original) (raw)
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Ion-induced molecular fragmentation: beyond the Coulomb explosion picture
Journal of Physics B: Atomic, Molecular and Optical Physics, 2000
The fragmentation of the CO molecule by O 7+ ion impact is investigated in two different energy regimes by fragment ion momentum spectroscopy. The improved resolution of the present kinetic energy release measurement together with application of a time-dependent wavepacket dynamics method used in conjunction with new high-level computations of a large number of dication potential energy curves enables one to unambiguously assign each line to an excited state of the transient molecular dication produced during the collision. This is the first direct experimental evidence of the limitations of the Coulomb explosion model to reproduce the molecular fragmentation dynamics induced by ion impact. Electron removal due to a capture process is shown to transfer less excitation to the target than direct ionization. At low collision velocity, the three-body interaction between the projectile and the two fragments is also clearly highlighted.
Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics
The Journal of Chemical Physics, 2018
The photodissociation dynamics of CH 3 I and CH 2 ClI at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815 nm probe pulse. Fragment ion momenta over a wide m/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH 2 ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion.
Strong laser-pulse-driven ionization and Coulomb explosion of hydrocarbon molecules
Physical Review A, 2012
Field ionization and Coulomb explosion of small hydrocarbon molecules driven by intense laser pulses are studied in a combined theoretical and experimental framework. The spectra of ejected protons calculated by the time-dependent density functional approach are in good agreement with the experimental data. The results of the simulations give detailed insight into the correlated electron and nuclear dynamics and complement the experiment with a time-dependent physical picture. It is demonstrated that the Coulomb explosion in the studied molecular systems is a sudden, all-at-once fragmentation where the ionization step is followed by a simultaneous ejection of the charged fragments.
Structural dynamics (Melville, N.Y.), 2018
We explore time-resolved Coulomb explosion induced by intense, extreme ultraviolet (XUV) femtosecond pulses from a free-electron laser as a method to image photo-induced molecular dynamics in two molecules, iodomethane and 2,6-difluoroiodobenzene. At an excitation wavelength of 267 nm, the dominant reaction pathway in both molecules is neutral dissociation via cleavage of the carbon-iodine bond. This allows investigating the influence of the molecular environment on the absorption of an intense, femtosecond XUV pulse and the subsequent Coulomb explosion process. We find that the XUV probe pulse induces local inner-shell ionization of atomic iodine in dissociating iodomethane, in contrast to non-selective ionization of all photofragments in difluoroiodobenzene. The results reveal evidence of electron transfer from methyl and phenyl moieties to a multiply charged iodine ion. In addition, indications for ultrafast charge rearrangement on the phenyl radical are found, suggesting that ti...
Quantitative molecular spectroscopy using Coulomb explosions
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1992
A quamitative analysis of the influence of multiple scattering on fast molecules dissociating in solids is made using a Monte Carlo technique. The simulations allow the computation of asymptotic velocities of all of the fragments after Coulomb explosion iacluding the effects of ion-solid interactions. Examples for deducing molecular structure using this method are given for two well-known molecular ions.
Two-fragment coincidence studies of molecular coulomb explosions induced by heavy ion impact
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989
Time-of-flight (TOF) spectroscopy was used to study the ionic species produced in collisions of 40 MeV Ar13+ with molecular oxygen. Ions from the dissociation of molecular ions having charges as high as lO+ were observed. The flight times of the first ion and the difference in flight times between the first and second ions of binary dissociation events were recorded event-by-event, thereby retaining their correlation. Off-line sorting of the data provided TOF and time difference spectra containing we11 resolved peaks associated with each of the charge division pairs produced in the dissociation process.
Physical Review Letters, 2013
Ionization and fragmentation of methylselenol (CH 3 SeH) molecules by intense (> 10 17 W=cm 2 ) 5 fs x-ray pulses (@! ¼ 2 keV) are studied by coincident ion momentum spectroscopy. We contrast the measured charge state distribution with data on atomic Kr, determine kinetic energies of resulting ionic fragments, and compare them to the outcome of a Coulomb explosion model. We find signatures of ultrafast charge redistribution from the inner-shell ionized Se atom to its molecular partners, and observe significant displacement of the atomic constituents in the course of multiple ionization.
On Routes to Ultrafast Dissociation of Polyatomic Molecules
The Journal of Physical Chemistry Letters, 2013
Dissociation pathways for complex polyatomic molecules can sometimes be obscure due to the multitude of degrees of freedom involved. Here, we suggest the description of a dissociation mechanism implying multimode dynamics on the barrierless potential energy surface. The mechanism is elaborated from the X-ray spectroscopic analysis of the ultrafast nuclear motion in core−shell excited molecules. We infer that in large molecules, dissociation pathways are observed to deviate from the two-body dissociation coordinate due to the internal motion of light linkages, which alters dissociation rates and may yield heavy products on very short time scales. The mechanism is exemplified with the case of 1-bromo-2-chloroethane, where the rotation of the C 2 H 4 -moiety leads to the dissociation of C−Cl or C−Br bonds in Cl2p or Br3d core-excited states, whose lifetimes last only ∼7 fs.
Physical Review Letters, 2009
We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization of H 2 molecules as a result of irradiation with an extreme-ultraviolet (XUV) pulse followed by an infrared (IR) pulse. In experiments where the duration of both the XUV and IR pulses are shorter than the vibrational period of H 2 þ , dephasing and rephasing of the vibrational wave packet that is formed in H 2 þ upon ionization of the neutral molecule by the XUV pulse is observed. In experiments where the duration of the IR pulse exceeds the vibrational period of H 2 þ (15 fs), a pronounced dependence of the H þ kinetic energy distribution on XUV-IR delay is observed that can be explained in terms of the adiabatic propagation of the H 2 þ wave packet on field-dressed potential energy curves.