Competition between rotational and vibrational autoionization in H2

O’Halloran, M. A.; Pratt, S. T.; Tomkins, F. S.; Dehmer, Joseph L.; Dehmer, Patricia M.

doi:10.1016/0009-2614(88)87447-5

Cited by 27 publications

(6 citation statements)

References 16 publications

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“…The autoionisation structure of H 2 has been investigated previously in a large number of studies [32][33][34][36][37][38][39]43], but these were generally constrained by the probing of wave-function density projected from the X(v = 0) ground state. The present three-laser excitation scheme, starting with the two-photon photolysis of H 2 S and preparing H 2 molecules in quantum states with wave function density at large internuclear separation (R ∼ 4-5 a.u.…”

Section: Observed Autoionisation Spectramentioning

confidence: 99%

“…are displayed. The autoionisation continua of H 2 have been amply studied via direct photoabsorption and photoionisation [32], in multi-photon studies [33,34], using synchrotron sources [35][36][37][38] and XUVlaser exctation [39]. However, these studies were limited to excitation from the X(v = 0) vibrational ground state, to rotational quantum numbers J ≤ 4, and hence to small internuclear separations of R ∼ 2 a.u.…”

Section: Introductionmentioning

confidence: 99%

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Excitation of H₂ at large internuclear separation: outer well states and continuum resonances

et al. 2019

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Bound and free quantum resonances of molecular hydrogen exhibiting wave-function density at large internuclear separation, R ∼ 4-5 a.u., are excited via multi-step laser spectroscopy. Highly excited vibrational levels of H 2 are prepared via two-photon UV-photolysis of H 2 S. Subsequent twophoton Doppler-free precision measurements are performed connecting X 1 + g (v = 11) levels with F 1 + g outer-well levels. Detection and spectroscopic labelling of the quantum states is assisted by further laser excitation into the auto-ionisation continuum employing a third UV-laser. Level energies of high rotational states (J = 6, 7) in the outer-well state F 1 + g (v = 0) are accurately determined. The three-laser study demonstrates a method for probing resonances in the H 2 ionisation continuum with wave-function density at large internuclear separation R = 4-5 a.u., large angular momenta J, and energy range 131,100-133,000 cm −1 , a hitherto unexplored territory.

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Section: Observed Autoionisation Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excitation of H₂ at large internuclear separation: outer well states and continuum resonances

et al. 2019

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“…Thus, when it is energetically allowed, vibrational autoionization with ⌬vϭϪ1 is expected to be fastest. Subsequently, experimental data on both diatomic and polyatomic molecules have supported this propensity rule; [13][14][15][16][17][18][19][20][21][22][23][24] in most cases, exceptions to the propen-sity rule have been explained in terms of competing electronic autoionization processes, which are not subject to this rule. [25][26][27] Although the ⌬vϭminimum propensity rule is still applicable in polyatomic molecules, additional questions about the mechanism for vibrational autoionization are raised.…”

Section: Introductionmentioning

confidence: 99%

Photoionization dynamics of the B 1E″ state of ammonia

Pratt

2002

The Journal of Chemical Physics

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Coherent polyatomic dynamics studied by femtosecond time-resolved photoelectron spectroscopy: Dissociation of vibrationally excited C S 2 in the 6 s and 4 d Rydberg states Two-photon excitation was used to excite a number of vibronic bands within the B 1 EЉ state of ammonia, including a number of combination bands involving the umbrella mode, 2 , and the asymmetric bend, 4 . Photoelectron spectra following single-photon ionization of these levels by the same laser provide insight into the character of the intermediate levels, and resolve questions raised by previous photoelectron studies via the B 1 EЉ state. Two-color double-resonance spectra were also recorded via selected rotational levels of the B 1 EЉ 2 3 4 1 state. These spectra show complex series of resonances that appear to converge to the X 2 A 2 Љ 2 3 4 1 state of the ion.Photoelectron spectra for a large number of these resonances show that ⌬v 2 ϭϪ1 and ⌬v 4 ϭϪ1 processes dominate, but that the branching between the two processes depends strongly on the specific resonance.

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“…In recent years, laser techniques employing double-resonance excitation schemes have allowed the photoionization dynamics of H2 to be studied with unprecedented detail. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] In a typical experiment, the first (pump) laser is used to excite ground-state molecules to a single rovibronic level by using a single-or multiphoton transition, and the second (probe) laser is used to excite single-photon transitions from the selected level to the energy region of interest. The overall process is then studied by the detection of photoelectrons, photoions, and/or photodissociation products.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper MQDT is applied to the calculation of the three different photoionization processes in H2 that were studied experimentally in a series of papers by O'Halloran et al 26,27,31,33,34 and that are shown schematically in Figure 1. All three of these processes involve pumping the two-photon E,F ' *, ' -X !…”

Section: Introductionmentioning

confidence: 99%

Multichannel Quantum Defect Theory and Double-Resonance Spectroscopy of Autoionizing Levels of Molecular Hydrogen

Jungen¹,

Pratt²,

Ross³

1995

J. Phys. Chem.

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Multichannel quantum defect theory has been used to calculate vibrational and rotational branching ratios in the photoionization of H2 excited to the E,F IX; state. The calculations take into account the interaction with doubly excited channels in the E,F l2; lower state, the energy and R dependence of the transition to the upper state, and the rovibronic channel interactions in the final states. The input data consist of the ionic potential energy curves and the known R-dependent quantum defects for the gerade and ungerade channels of H2. All these parameters are used without adjustment. The theoretical results are compared with the results of earlier double-resonance experiments. This detailed comparison shows that the R dependence of the transition dipole moments has considerable influence on the resonance profiles and the branching ratios. The overall agreement with the experimental results is excellent, and most of the observed discrepancies can be accounted for by the competing decay processes of predissociation and fluorescence, which were not included in the calculations.

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Competition between rotational and vibrational autoionization in H2

Cited by 27 publications

References 16 publications

Excitation of H₂ at large internuclear separation: outer well states and continuum resonances

Excitation of H₂ at large internuclear separation: outer well states and continuum resonances

Photoionization dynamics of the B 1E″ state of ammonia

Multichannel Quantum Defect Theory and Double-Resonance Spectroscopy of Autoionizing Levels of Molecular Hydrogen

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Competition between rotational and vibrational autoionization in H2

Cited by 27 publications

References 16 publications

Excitation of H2 at large internuclear separation: outer well states and continuum resonances

Excitation of H2 at large internuclear separation: outer well states and continuum resonances

Photoionization dynamics of the B 1E″ state of ammonia

Multichannel Quantum Defect Theory and Double-Resonance Spectroscopy of Autoionizing Levels of Molecular Hydrogen

Contact Info

Product

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Excitation of H₂ at large internuclear separation: outer well states and continuum resonances

Excitation of H₂ at large internuclear separation: outer well states and continuum resonances