Coincidence momentum imaging of ejection of hydrogen molecular ions from methanol in intense laser fields

Okino, Tomoya; Furukawa, Yusuke; Liu, Peng; Ichikawa, Takayuki; Itakura, Ryuji; Hoshina, Kennosuke; Yamanouchi, Kaoru; Nakano, H.

doi:10.1016/j.cplett.2005.11.059

Cited by 74 publications

(65 citation statements)

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“…It is known that the ejection of H + through the pathway (2) proceeds very rapidly within the time range of 70-290 fs 13 . Therefore, it is probable that the large portion of H + are produced via the pathway (2) from the precursor dications prepared in a much higher energy region above TS2, resulting in the nonoscillating components seen in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, we interpreted the mechanism of H 3 + formation from dication of methanol theoretically as a unimolecular decomposition process in which a long-lived neutral moiety of H 2 , formed within a dication molecule, abstracts a proton in the other moiety having the charge of +2 11 . Through a series of our studies on the formation of H 3 + from hydrocarbon molecules by the irradiation of ultrashort intense laser pulses 7,10,[12][13][14] , we showed that the hydrocarbon dications from which H 3 + is ejected are all long lived, and that their lifetimes are comparable to or longer than a period of the overall rotation of the dications. These findings mean that the intramolecular vibrational-energy redistribution proceeds to a large extent within the energized dications prior to the ejection of H 3 + .…”

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Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization

et al. 2018

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When hydrocarbon molecules are exposed to an intense laser field, triatomic hydrogen molecular ion, H 3 + , is ejected. Here we describe pump-probe measurements of the ejection of H 3 + from methanol dication with high temporal resolution using intense few-cycle laser pulses and find a long-lasting periodic increase in the yield of H 3 + . We show that H 3 + ejection is the lowest energy decomposition channel and that its yield is enhanced each time when the vibrational wave packet coming back to the inner turning point of methanol cation is projected onto the dication potential energy surface. We also show that the time-resolved measurement of the yield of H 3 + is an efficient tool not only for probing ultrafast nuclear dynamics of hydrocarbon cations but also for deriving vibrational frequencies of hydrocarbon cations with high precision.

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Section: Resultsmentioning

confidence: 99%

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Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization

et al. 2018

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“…By contrast, we have shown in the present study the possibility of the existence of a long-lived neutral D 2 (H 2 ) moiety, which vibrates and rotates before reaching the transition state for the ejection of D 3 + (H 3 + ). In the series of our experimental studies on hydrocarbon molecules such as methanol, 2 cyclohexane, 12 allene, 13 methylacetylene, 14 and ethane, 15 the angular distributions of the fragment ion H 3 + were reported to be almost isotropic, i.e., the lifetimes of the precursor parent dications leading to the ejection of H 3 + were found to be comparable with or even longer than the overall rotational motion of the parent dication (∼ps). The mechanism of the existence of energized dication molecules for such a long period of time has been an unsolved issue in these years, but the present theoretical study strongly suggests that the existence of a long lived, vibrating, and rotating H 2 moiety within a dication molecule is the origin to the long lifetime of the dication molecule prior to the ejection of H 3 + .…”

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confidence: 99%

“…On the other hand, the yield of the ejection of H + from the hydroxyl group is 0.4% and that of the ejection of HD 2 + is 1.6%. The smaller yields of HD 2 + with respect to D 3 Fig. 1(b).…”

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“…It should be noted that the formation of a neutral D 2 moiety was commonly identified in all the trajectories leading to the formation of HD 2 + and D 3 + . For describing the motion of the D 2 moiety formed within CH 3 OH 2+ , we introduce three parameters, R 1 , R 2 , and θ , where R 1 is the vector from one of the D atoms, D(1), to the other, D (2), that eventually form the D 2 moiety, R 2 is the vector from the center of the two D atoms to the center of C and O atoms, and the angle θ is the inner angle between R 1 and R 2 .…”

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Communication: Long-lived neutral H2 in hydrogen migration within methanol dication

Nakai¹,

Katō²,

Kono³

et al. 2013

The Journal of Chemical Physics

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The ejection of triatomic hydrogen molecular ions HD2+ and D3+ from CD3OH2+ is investigated by first-principle molecular dynamics simulation. Two C–D chemical bonds are found to be broken to form a neutral D2 moiety that vibrates, rotates, and moves for a relatively long period of time (20–330 fs) towards a transition state leading to the ejection of HD2+ or D3+. The formation of such a long-lived neutral D2 moiety within a hydrocarbon molecule interprets well the recent experimental findings of the long lifetime of doubly charged energized hydrocarbon molecules prior to the ejection of H3+.

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Two pathways and an isotope effect in H3+ formation following double ionization of methanol

et al. 2021

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The trihydrogen ion has a central role in creating complex molecules in the interstellar medium. Therefore, its formation and destruction mechanisms in high photon energy environments involving organic molecules are drawing significant experimental and theoretical attention. Here, we employ a combination of time‐resolved ultrafast extreme‐ultraviolet pump and near‐infrared probe spectroscopy applied to the deuterated CH3OD methanol molecule. Similar to other double‐ionization studies, the isotopic labeling reveals two competing pathways for forming trihydrogen: A) normalH3++COnormalH+ and B) normalH3++HCnormalO+. We validate our high‐level ab initio nonadiabatic molecular dynamic simulations by showing that it closely reproduces the essential features of the measured kinetic energy release distribution and branching ratios of the two pathways of the deuterated system. The success of ab initio simulation in describing single photon double‐ionization allows for an unprecedented peek into the formation pathways for the undeuterated species, beyond present experimental reach. For this case, we find that the kinetic energy release of pathway B shifts to lower energies by more than 0.6 eV due to a dynamical isotope effect. We also determine the mechanism for trihydrogen formation from excited states of the dication and elucidate the isotope effect's role in the observed dynamics.

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Coincidence momentum imaging of ejection of hydrogen molecular ions from methanol in intense laser fields

Cited by 74 publications

References 10 publications

Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization

Coherent vibrations in methanol cation probed by periodic H3+ ejection after double ionization

Communication: Long-lived neutral H2 in hydrogen migration within methanol dication

Two pathways and an isotope effect in H3+ formation following double ionization of methanol

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