PFI-ZEKE photoelectron and high resolution photoionization spectra of ND<sub>3</sub>with MQDT simulations

Duggan, L.; Raunhardt, Matthias; Schäfer, Martin; Hollenstein, U.; Softley, T. P.; Merkt, F.

doi:10.1080/00268971003649315

Cited by 6 publications

(10 citation statements)

References 32 publications

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“…[39][40][41] One consequence of symmetry and nuclear spin constraints is that only transitions originating from the lower (+) inversion component of the ground state appear in bands in which the final ߥ ଶ is even, whereas only transitions from the upper (−) inversion 35 component appear in bands with final ߥ ଶ odd. Therefore, two vibrational transitions must be excited to probe all individual rotational states.…”

Section: B Rotational Levels and Initial State Selection Of Ndmentioning

confidence: 99%

“…9 Fully deuterated ammonia, ND 3 , has been observed in prestellar cores. 10 Cheung et al 11 noted that the 35 observed NH 3 emission intensities from interstellar sources do not correspond to a single rotational temperature. In addition, the inversion transition was detected for the rotational level j k = 11 9 , 12 which should not be populated at interstellar temperatures of 10-300 K, and the j k = 3 3 inversion transition has been predicted 13 40 and observed 14 to exhibit maser activity.…”

Section: Introductionmentioning

confidence: 99%

“…However, the laser bandwidth was ~0.3 cm -1 and the ~4.5 mJ energy per pulse of the laser power broadened the transitions 35 sufficiently that Doppler scanning was unnecessary.…”

mentioning

confidence: 99%

“…The radius of the recorded ion image is then directly proportional to the CM-55 frame speed of the ions at their point of formation by REMPI. For the ionization schemes employed here, the recoil of the electron from the ion (deriving from the excess energy of three UV photons above the 10.08 eV 34,35 ionization energy of ND 3 ) can impart up to 20 ms -1 to the ND 3 + corresponding to an ~3 pixel 60 blurring of …”

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confidence: 99%

“…25 At this level of resolution of the dynamics of a scattering process, rigorous comparisons can be drawn between experimental measurements and the outcomes of quantum mechanical (QM) scattering calculations. Such comparisons provide stringent tests of the accuracy of ab initio 35 for the collisional processes of interest. Although there is a significant body of work on inelastic scattering of diatomic molecules, such detailed experimental and computational investigations for scattering of polyatomic molecules remain relatively rare.…”

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confidence: 99%

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State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

Tkáč

Saha

Yang

et al. 2014

Phys. Chem. Chem. Phys.

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angular distributions. For small changes in the rotational angular momentum quantum number (j), the ND 3 is predominantly forward scattered, but the scattering shifts to the sideways and backward directions as ∆j increases. For scattering into a given ݆Ԣ ᇱ േ state, crosssections for collisions that conserve the +/-symmetry associated with the ND 3 inversion vibration are larger and generally more forward scattered than the corresponding symmetry-changing processes.

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Section: B Rotational Levels and Initial State Selection Of Ndmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…However, the laser bandwidth was ~0.3 cm -1 and the ~4.5 mJ energy per pulse of the laser power broadened the transitions 35 sufficiently that Doppler scanning was unnecessary.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

Tkáč

Saha

Yang

et al. 2014

Phys. Chem. Chem. Phys.

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Sensitive Low-Recoil VUV 1 + 1′ REMPI Detection of ND₃

Kuijpers,

Kalaitzis,

Sakkoula

et al. 2024

J. Phys. Chem. A

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In molecular beam scattering experiments, an important technique for measuring product energy and angular distributions is velocity map imaging following photoionization of one or more scattered species. For studies with cold molecular beams, the ultimate resolution of such a study is often limited by the product detection process. When state-selective ionization detection is used, excess energy from the ionization step can transfer to kinetic energy in the target molecular ion−electron pair, resulting in measurable cation recoil. With state-of-the-art molecular beam technology, velocity spreads as small as a few m/s are possible, thus a suitable product detection scheme must be not only highly sensitive, state-selective, and background-free, it must also produce significantly less cation recoil than the velocity spread of the molecular beams undergoing cold collisions. To date this has only been possible with the NO molecule, and our goal here is to extend this minimal-recoil capability to the fully deuterated ammonia molecule, ND 3 . In this article a resonance enhanced multi photon ionization (REMPI) detection scheme for ND 3 is presented that imparts sufficiently low recoil energy to the ions, allowing, for the first time, high-resolution imaging of ND 3 collision products in cold molecule scattering experiments with HD. The excitation step of the 1 + 1′ REMPI scheme requires vacuum ultra-violet (VUV) photons of ∼160 nm, which are generated through four-wave-mixing in Xe. We varied the wavelength of the second, ionization step between 434 and 458 nm, exciting ND 3 to a wide range of autoionizing neutral states. By velocity mapping the photoelectrons resulting from the detection scheme, it was possible to fully chart the ion recoil across this range with vibrational resolution for the final ionic states. Additionally, rotational resolution in the photoionization dynamics was achieved for selected excitation energies near one of the vibrational thresholds. Many of the peaks in the spectrum of autoionizing Rydberg states are assigned to specific Rydberg series using a simple Rydberg formula model.

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Threshold ionization spectroscopy of H₂O, HDO and D₂O and low-lying vibrational levels of HDO⁺and D₂O⁺

2015

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Rotationally resolved photoelectron spectra of jet-cooled H 2 O, HDO and D 2 O have been recorded near the origin of thẽ X + ←X photoionising transition following single-photon ionization using the complementary techniques of mass-analysed threshold-ionization (MATI) and pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy. A gas mixture of H 2 O, HDO and D 2 O with Ar was obtained by mixing H 2 O ( ) and D 2 O ( ) in a reservoir and bubbling Ar gas through the mixture. To unambiguously assign the photoelectron bands to H 2 O, HDO or D 2 O, the PFI-ZEKE photoelectron spectra of the mixture were compared to MATI spectra and to spectra of H 2 O. Analysis of the rotational structure of the origin bands (HDO and D 2 O and of the transitions to the (010), (020) and (100) levels of D 2 O + and the first excited level of the O-D stretching mode of HDO + provided new information on the photoionization dynamics of water and the energy level structure of HDO + and D 2 O + . IntroductionWater (H 2 O) and its cation (H 2 O + ) are prototypical small molecules [1] and play an important role on earth and in the universe. Studies of H 2 O, HDO and D 2 O by vacuum-ultraviolet photoelectron and photoionization spectroscopy provide information on their interaction with short-wavelength radiation, on their photoionization dynamics and on the energy-level structure and dynamics of the cations [2-16]. The valence-shell photoionization of water, either in a single-photon process from theX 1 A 1 ground state or in multiphoton processes through electronically excited states, has provided access to a wide range of rovibrational levels of theX + 2 B 1 andÃ + 2 A 1 states of the cation, which are degenerate in linear (D ∞h ) configurations and subject to the Renner-Teller effect [17][18][19]. Whereas H 2 O + in the first excited state is quasilinear, the equilibrium geometry of the ground cationic state is bent and similar to that of the ground state of the neutral. Consequently, many more vibrational levels of theÃ + 2 A 1 state are accessible by photoionization from the ground state of the neutral than is the case for theX + 2 B 1 state [2,4,5,12,15,16].The vacuum-ultraviolet (VUV) photoelectron spectrum of theX + 2 B 1 ←X 1 A 1 photoionising transition of water thus consists of only a few vibrational bands, i.e., a strong origin band and weak and short progressions in the bending (0, v + 2 , 0) and symmetric stretching (v + 1 , 0, 0) modes [4,12,15,16]. The weakness of the bands associated with

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PFI-ZEKE photoelectron and high resolution photoionization spectra of ND₃with MQDT simulations

Cited by 6 publications

References 32 publications

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

Sensitive Low-Recoil VUV 1 + 1′ REMPI Detection of ND₃

Threshold ionization spectroscopy of H₂O, HDO and D₂O and low-lying vibrational levels of HDO⁺and D₂O⁺

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PFI-ZEKE photoelectron and high resolution photoionization spectra of ND3with MQDT simulations

Cited by 6 publications

References 32 publications

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND3with He

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND3with He

Sensitive Low-Recoil VUV 1 + 1′ REMPI Detection of ND3

Threshold ionization spectroscopy of H2O, HDO and D2O and low-lying vibrational levels of HDO+and D2O+

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PFI-ZEKE photoelectron and high resolution photoionization spectra of ND₃with MQDT simulations

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

State-to-state resolved differential cross sections for rotationally inelastic scattering of ND₃with He

Sensitive Low-Recoil VUV 1 + 1′ REMPI Detection of ND₃

Threshold ionization spectroscopy of H₂O, HDO and D₂O and low-lying vibrational levels of HDO⁺and D₂O⁺