The direct ultraviolet absorption spectrum of the A'~A2" .rarw. ~X'A1 transition of jet-cooled ammonia

Vaida, Veronica; Hess, W. N.; Roebber, J. L.

doi:10.1021/j150660a006

Cited by 63 publications

(48 citation statements)

References 3 publications

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“…This is analogous to the progressions observed in the Ã r X absorption spectra of both NH 3 and ND 3 . 10,23,24 The band origins 2 0 0 are in agreement with earlier studies and lie at ∼215 nm. 11,15,16 With the studies being performed at room temperature, the band origins are not resolved for the NH 2 D and ND 2 H species.…”

Section: Preparation and Characterization Of Nh 2 D And Nd 2 Hsupporting

confidence: 90%

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H

2000

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The adiabatic dissociation dynamics of NH 2 D(Ã ) and ND 2 H(Ã ) have been probed by time-resolved Fourier transform infrared emission spectroscopy. A product-state spectral pattern recognition technique is employed to separate out the emission features arising from the different photofragmentation channels following the simultaneous excitation of mixtures of the four parent molecules NH 3 , NH 2 D, ND 2 H, and ND 3 at 193.3 nm. The rotational energy partitioning about the primary a-axis of the fragments NH 2 (Ã ,υ 2 ′ ) 0) and ND 2 (Ã ,υ 2 ′ ) 0) from NH 2 D(Ã ) and ND 2 H(Ã ), respectively, is bimodal. We suggest that the origin of this excitation reflects the competition between two distinct dissociation mechanisms that sample two different geometries during the bond cleavage. A larger quantum yield for producing ND 2 (Ã ,υ 2 ′ ) 0) from the photodissociation of ND 2 H than ND 3 is attributed to the lower dissociation energy of the N-H as compared with the N-D bond and to the enhanced tunneling efficiency of H atoms over D atoms through the barrier to dissociation. Similarly, the quantum yield for producing the NH 2 (Ã ,υ 2 ′ ) 0) fragment is lower when an N-D bond must be cleaved in comparison to an N-H bond. Photodissociation of ND 2 H by cleavage of an N-H bond leads to an ND 2 (Ã ) fragment with a much larger degree of vibrational excitation (υ 2 ′ ) 1,2), accompanied by substantial rotation about the minor b/c-axes, than when an N-D bond is cleaved in the photodissociation of ND 3 . The quantum yield for producing NHD(Ã ) is larger for cleavage of an N-H bond from NH 2 D than by cleavage of an N-D from ND 2 H.

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Section: Preparation and Characterization Of Nh 2 D And Nd 2 Hsupporting

confidence: 90%

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H

2000

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“…Photoabsorption [1][2][3][4][5][6] and electron energy-loss spectra [7,8] show a series of excited electronic states, each being characterized by only one vibrational progression and assigned to the v 2 inversion bending mode [1][2][3][4][5][6][7][8]. All these states, of Rydberg character (noted in the literature by Ã to H ), have been assigned [1][2][3][4][5][6][7][8]. A number of these states were analyzed above the ionization limit of 10.072 eV, e.g.…”

Section: The Autoionization Spectramentioning

confidence: 99%

“…Below the first ionization limit the vibronic spectrum of NH 3 has been abundantly investigated by numerous workers using various techniques [1][2][3][4][5][6][7][8]. It is generally well established that all the ammonia electronic excited states are of Rydberg character arising from the excitation of one of the nitrogen non-bonding lone pair electrons.…”

Section: Introductionmentioning

confidence: 99%

The photoionization of ammonia revisited. The vibrational autoionization of NH3 and its three isotopomers in the 10–12 eV photon energy range

et al. 1991

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The photoionization efficiency curves of NH 3 and its three isotopomers have been investigated in the photon energy range of the first ionized state. From the analysis of the corresponding vibrational structure, wavenumbers (ω e ) and anharmonicity constants (ω e x e ) are deduced. The detailed investigation of the abundant autoionization structure tends to show the adiabatic ionization energy to be 10.072 ± 0.010 eV for NH 3 , NH 2 D and NHD 2 and 10.083 ± 0.010 eV for ND 3 . All autoionization features were classified in vibrational progressions (v 2 bending mode) belonging to nsa 1 (or nd) and npe (n=5, 6, 7) Rydberg series. Vibrational autoionization occurs through ∆v transitions up to -9. A qualitative analysis of the intensity distribution of these series strongly supports that transitions involving odd ∆v values are favoured. This observation can be understood by applying group theoretical considerations to the theory of vibrational autoionization.

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“…The associated 2 0 n vibronic progressions in both NH 3 and ND 3 have been identified in one-photon vuv absorption. [1][2][3]20,21 Our knowledge of the B state has been greatly enhanced by two-photon REMPI spectroscopy studies both under beam conditions 22 and, with sub-Doppler resolution, in the bulk. 23 The latter study yielded molecule limited linewidths of individual ND 3 (B-X) rovibronic transitions, thereby enabling determination of a ͑rotational level independent͒ lifetime of ϳ0.25 ns for levels of the ND 3 (B) state with 2 Јр6.…”

Section: Introductionmentioning

confidence: 99%

The spectroscopy of high Rydberg states of ammonia

Langford

Orr‐Ewing

Morgan

et al. 1998

The Journal of Chemical Physics

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General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. This paper extends our knowledge of the higher excited states of the ammonia molecule by presenting detailed measurements of the 2ϩ1 resonance enhanced multiphoton ionization ͑REMPI͒ spectrum of both NH 3 and ND 3 obtained following excitation in the wavelength range 298-242 nm, i.e., at energies up to the first ionization energy. Complementary analyses of the wavelength resolved REMPI spectrum and the accompanying REMPI-photoelectron spectra leads to the identification of ten new Rydberg origins of NH 3 ͑four for ND 3 ͒ with principal quantum numbers nр8 and, in most cases, of the accompanying out-of-plane bending vibrational progression. Symmetry assignments for the various newly identified excited states are offered, based on band contour simulation and/or quantum defect considerations. Dominant amongst these are the ẼЉThe present work serves to reinforce the previously noted dominance of np←1a 2 Љ Rydberg excitations in the 2ϩ1 REMPI spectrum of ammonia. In addition, the adiabatic ionization energy of ND 3 is estimated to be 82 280Ϯ40 cm Ϫ1 based on the assumption that analogous Rydberg states of NH 3 and ND 3 will have very similar quantum defects.

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The direct ultraviolet absorption spectrum of the A'~A2" .rarw. ~X'A1 transition of jet-cooled ammonia

Cited by 63 publications

References 3 publications

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H

The photoionization of ammonia revisited. The vibrational autoionization of NH3 and its three isotopomers in the 10–12 eV photon energy range

The spectroscopy of high Rydberg states of ammonia

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The direct ultraviolet absorption spectrum of the A'~A2" .rarw. ~X'A1 transition of jet-cooled ammonia

Cited by 63 publications

References 3 publications

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH2D and ND2H

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH2D and ND2H

The photoionization of ammonia revisited. The vibrational autoionization of NH3 and its three isotopomers in the 10–12 eV photon energy range

The spectroscopy of high Rydberg states of ammonia

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Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H

Competition between N−H and N−D Bond Cleavage in the Photodissociation of NH₂D and ND₂H