Observation of Direct Dissociative Ionization in Molecular Hydrogen

Баккер, Б. Л. Г.; Parker, David H.; Zande, Wim J. van der

doi:10.1103/physrevlett.86.3272

Cited by 15 publications

(10 citation statements)

References 18 publications

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“…3(a) Σ þ u Þ repulsive state, as illustrated in Fig. 1(b), close to the prediction of the Condon-reflection approximation [39,40]. The DI spectra therefore also demonstrate a strong contribution from the H 2 (B 1 Σ þ u , v ¼ 9) state at large R distances populating the H þ 2 ð2pσ u 2 Σ þ u Þ ionization continuum.…”

supporting

confidence: 77%

Control of H2 Dissociative Ionization in the Nonlinear Regime Using Vacuum Ultraviolet Free-Electron Laser Pulses

et al. 2018

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The role of the nuclear degrees of freedom in nonlinear two-photon single ionization of H_{2} molecules interacting with short and intense vacuum ultraviolet pulses is investigated, both experimentally and theoretically, by selecting single resonant vibronic intermediate neutral states. This high selectivity relies on the narrow bandwidth and tunability of the pulses generated at the FERMI free-electron laser. A sustained enhancement of dissociative ionization, which even exceeds nondissociative ionization, is observed and controlled as one selects progressively higher vibronic states. With the help of ab initio calculations for increasing pulse durations, the photoelectron and ion energy spectra obtained with velocity map imaging allow us to identify new photoionization pathways. With pulses of the order of 100 fs, the experiment probes a timescale that lies between that of ultrafast dynamical processes and that of steady state excitations.

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supporting

confidence: 77%

Control of H2 Dissociative Ionization in the Nonlinear Regime Using Vacuum Ultraviolet Free-Electron Laser Pulses

et al. 2018

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“…34 The photoelectron yield spectra obtained for HCl and HBr do not contain features to support a contribution of dissociative ionization and, for simplicity, we assume that channel ͑4͒ has, at best, a minor contribution to the formation of protons. 34 The photoelectron yield spectra obtained for HCl and HBr do not contain features to support a contribution of dissociative ionization and, for simplicity, we assume that channel ͑4͒ has, at best, a minor contribution to the formation of protons.…”

Section: ͑7͒mentioning

confidence: 99%

Proton formation in 2+1 resonance enhanced multiphoton excitation of HCl and HBr via (Ω=) Rydberg and ion-pair states

Romanescu

Loock

2007

The Journal of Chemical Physics

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Molecular beam cooled HCl was state selected by two-photon excitation of the V (1) summation operator(0(+)) [v=9,11-13,15], E (1) summation operator(0(+)) [v=0], and g (3) summation operator(-)(0(+)) [v=0] states through either the Q(0) or Q(1) lines of the respective (1,3) summation operator(0(+))<--<--X (1) summation operator(0(+)) transition. Similarly, HBr was excited to the V (1) summation operator(0(+)) [v=m+3, m+5-m+8], E (1) summation operator(0(+)) [v=0], and H (1) summation operator(0(+)) [v=0] states through the Q(0) or Q(1) lines. Following absorption of a third photon, protons were formed by three different mechanisms and detected using velocity map imaging. (1) H(*)(n=2) was formed in coincidence with (2)P(i) halogen atoms and subsequently ionized. For HCl, photodissociation into H(*)(n=2)+Cl((2)P(12)) was dominant over the formation of Cl((2)P(32)) and was attributed to parallel excitation of the repulsive [(2) (2)Pi4llambda] superexcited (Omega=0) states. For HBr, the Br((2)P(32))Br((2)P(12)) ratio decreases with increasing excitation energy. This indicates that both the [(3) (2)Pi(12)5llambda] and the [B (2) summation operator5llambda] superexcited (Omega=0) states contribute to the formation of H(*)(n=2). (2) For selected intermediate states HCl was found to dissociate into the H(+)+Cl(-) ion pair with over 20% relative yield. A mechanism is proposed by which a bound [A (2) summation operatornlsigma] (1) summation operator(0(+)) superexcited state acts as a gateway state to dissociation into the ion pair. (3) For all intermediate states, protons were formed by dissociation of HX(+)[v(+)] following a parallel, DeltaOmega=0, excitation. The quantum yield for the dissociation process was obtained using previously reported photoionization efficiency data and was found to peak at v(+)=6-7 for HCl and v(+)=12 for HBr. This is consistent with excitation of the repulsive A(2) summation operator(12) and (2) (2)Pi states of HCl(+), and the (3) (2)Pi state of HBr(+). Rotational alignment of the Omega=0(+) intermediate states is evident from the angular distribution of the excited H(*)(n=2) photofragments. This effect has been observed previously and was used here to verify the reliability of the measured spatial anisotropy parameters.

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“…Extensive studies of the ionization and dissociation of molecules have been carried out in previous studies by using various projectiles such as ions [1][2][3], photons [4][5][6][7], and electrons [8][9][10]. The main purposes of such studies are to investigate the various decay pathways and to clarify which parameters determine these decay pathways.…”

Section: Introductionmentioning

confidence: 99%

Formation of protons from dissociative ionization of methane induced by 54 eV electrons

Ren

et al. 2011

Phys. Rev. A

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The production mechanisms of protons in dissociation of methane by 54 eV electron impact is investigated using the reaction microscope. By measuring all three charged particles in the final state in triple coincidence, the energy deposited in the target is determined. It is found that the (2a 1 ) −1 (npt 2 ) 1 , (2a 1 ) −1 , (1t 2 ) −2 (3a 1 ) 1 , and (2a 1 ) −2 (3a 1 ) 1 states of the intermediate CH 4 + make the major contributions to the formation of protons at this incident energy. The decay of each state results in a different kinetic energy distribution of protons. Possible decay mechanisms of these states are analyzed.

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Observation of Direct Dissociative Ionization in Molecular Hydrogen

Cited by 15 publications

References 18 publications

Control of H2 Dissociative Ionization in the Nonlinear Regime Using Vacuum Ultraviolet Free-Electron Laser Pulses

Control of H2 Dissociative Ionization in the Nonlinear Regime Using Vacuum Ultraviolet Free-Electron Laser Pulses

Proton formation in 2+1 resonance enhanced multiphoton excitation of HCl and HBr via (Ω=) Rydberg and ion-pair states

Formation of protons from dissociative ionization of methane induced by 54 eV electrons

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