Photoelectron imaging following 2 + 1 multiphoton excitation of HBr

Romanescu, Constantin; Loock, Hans‐Peter

doi:10.1039/b602435a

Cited by 24 publications

(23 citation statements)

References 51 publications

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“…The focus of the work summarized here lies in the investigation of the photoionization of HCl following two-photon excitation of its Rydberg states. For HBr [1][2][3], and to a lesser extent for HI [4], similar studies and similar conclusions have been reported, whereas much less is known about HF, most probably due to the difficulty of state-selective fluorine atom detection [5] and to the more problematic chemical properties of HF making gas handling significantly more demanding.…”

Section: Introductionsupporting

confidence: 53%

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

Maul

Chichinin

Gericke

2011

Journal of Atomic, Molecular, and Optical Physics

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The competition between multiphoton ionization and fragmentation in the diatomic molecule hydrogen chloride is reviewed. Emphasis is laid on recent experimental results employing chemical imaging methods in order to obtain kinetic energy distributions and angular distributions of photoproducts. The energy range considered is 15 to 20 eV, equivalent to the absorption of three or four photons in the ultraviolet wavelength range. The role of Rydberg states as resonantly excited intermediate states in the ionization/fragmentation processes is assessed. Mixing among 1 Σ + states gives rise to peculiarly shaped double minimum potential energy curves which allow for the production of hydrogen and chlorine atomic and ionic fragments via several competing pathways, in addition to the production of molecular HCl + ions. States with different electronic properties show a qualitatively different behaviour from Σ + states. Accidental resonances between states of differing orbital angular momentum or multiplicity serve to override these differences and cause subtle as well as significant deviations from the unperturbed behaviour.

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Section: Introductionsupporting

confidence: 53%

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

Maul

Chichinin

Gericke

2011

Journal of Atomic, Molecular, and Optical Physics

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“…14 The larger spin-orbit interaction in HBr compared to HCl results in a departure from a Hund's case ͑a͒ description with the result that, for the perpendicular two-photon pathway, both the 1 ⌸ 1 and 3 ⌸ 1 states are able to contribute. [43][44][45] More importantly, for the parallel pathway, the 3 ⌸ 0 (⍀ϭ0) intermediate state gains strength through spin-orbit mixing with the ground state.…”

Section: Photodissociation Of Hbrmentioning

confidence: 99%

“…The effects of this prepared angular momentum polarization upon the observed vector correlations are pronounced and complicated. [12][13][14] Control over the prepared angular momentum polarization provides a powerful tool for the interrogation of the photodissociation dynamics, allowing for control over which electronic states are active in the photodissociation. 12,15 In essence, a state of known angular momentum polarization ͑and molecular axis alignment/orientation͒ allows for control over the molecular frame geometry in the laboratory frame and so control over the molecular frame transition dipole moment.…”

Section: Introductionmentioning

confidence: 99%

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

Manzhos

Romanescu

Loock

et al. 2004

The Journal of Chemical Physics

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A formalism for calculating the angular momentum polarization of an atom or a molecule following two-photon excitation of a J-selected state is presented. This formalism is used to interpret the H atom photofragment angular distributions from single-photon dissociation of two-photon rovibronically state selected HCl and HBr prepared via a Q-branch transition. By comparison of the angular distributions measured using the velocity map imaging technique with the theoretical model it is shown that single-photon dissociation of two-photon prepared states can be used for pathway identification, allowing for the identification of the virtual state symmetry in the two-photon absorption and/or the symmetry of the dissociative state. It is also shown that under conditions of excitation with circularly polarized light, or for excitation via non-Q-branch transitions with linearly polarized light the angular momentum polarization is independent of the dynamics of the two-photon transition and analytically computable.

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“…1-13͒ and HBr, [14][15][16][17][18][19] are perhaps the most studied diatomic molecules in the field of photodissociation and photoionization dynamics. 1-13͒ and HBr, [14][15][16][17][18][19] are perhaps the most studied diatomic molecules in the field of photodissociation and photoionization dynamics.…”

Section: Introductionmentioning

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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Photoelectron imaging following 2 + 1 multiphoton excitation of HBr

Cited by 24 publications

References 51 publications

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

Two-photon state selection and angular momentum polarization probed by velocity map imaging: Application to H atom photofragment angular distributions from the photodissociation of two-photon state selected HCl and HBr

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

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