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.

Rydberg excited states of the OCS molecule in the energy range 70500-86000 cm Ϫ1 have been investigated via the two and three photon resonance enhancements they provide in the mass resolved multiphoton ionization ͑MPI͒ spectrum of a jet-cooled sample of the parent molecule. Spectral interpretation has been assisted by companion measurements of the kinetic energies of the photoelectrons that accompany the various MPI resonances. The present study supports the earlier conclusions of Weinkauf and Boesl ͓J. Chem. Phys. 98, 4459 ͑1993͔͒ regarding five Rydberg origins in the 70500-73000 cm Ϫ1 energy range, attributable to, respectively, states of 3 ⌸, 1 ⌸, 3 ⌬, 1 ⌬ and 1 ⌺ ϩ symmetry arising from the 4p←3 orbital promotion. We also identify a further 21 Rydberg origins at higher energies. These partition into clumps with quantum defects ca. 3.5 and 4.5, which we associate with the orbital promotions np←3 (nϭ5,6), and others with near integer quantum defect which are interpretable in terms of excitation to s,d and ͑possibly͒ f Rydberg orbitals. We also identify MPI resonances attributable to CO(X 1 ⌺ ϩ ) fragments and to S atoms in both their ground ( 3 P) and excited ( 1 D) electronic states. Analysis of the former resonances confirms that the CO(X) fragments resulting from one photon dissociation of OCS at excitation wavelengths ca. 230 nm are formed with a highly inverted, bimodal rotational state population distribution, whilst the latter are consistent with previous reports of the wavelength dependence for forming ground and excited state S atoms in the near uv photolysis of OCS.

Resonance-enhanced multiphoton ionization photoelectron spectroscopy of Rydberg states of N2O below the X ionization limit Scheper, C.R.; Kuijt, J.; Buma, W.J.; de Lange, C.A. 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. A three-photon resonance-enhanced multiphoton ionization spectroscopic study on N 2 O is carried out in the spectral range from 80 000 cm Ϫ1 up to the lowest ionization limit at 103 963 cm Ϫ1. High-resolution photoelectron spectroscopy is used to identify and characterize the observed excited states. Eighteen origins are reported which have either not been assigned before or are reassigned now. Moreover, the photoelectron spectra taken at higher-lying resonances often show extensive vibronic coupling with the near-resonant vibronic manifolds built on lower-lying origins.

Photoionization and photodissociation dynamics of H2 after (3+1) REMPI via the B state Scheper, C.R.; Buma, W.J.; de Lange, C.A.; van der Zande, W.J. 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. We present a study of the molecular photoionization and photodissociation processes in molecular hydrogen occurring after one-photon absorption from various rovibrational levels (vЈϭ3 -22, JЈ ϭ0 -3͒ of the B 1 ⌺ u ϩ (1s g )(2p u ) state using resonance-enhanced multiphoton ionization in combination with high-resolution photoelectron spectroscopy ͑REMPI-PES͒. For one-photon absorption from the vЈϭ3 -8 levels, molecular photoionization competes with photodissociation into a ground-state atom and an atom in an nϭ2 excited state. A detailed comparison of the photoelectron spectra obtained via different rotational branches and vibrational levels strongly indicates that singly excited bound 1 ⌺ g ϩ and 1 ⌸ g Rydberg states at the four-photon level exert a significant influence on the final state distributions of H 2 ϩ . In contrast, one-photon absorption from the vЈϭ9 and higher levels leads almost exclusively to dissociation into a ground-state atom and an excited-state atom with nϾ2. Excited atomic fragments are ionized in a one-photon absorption step, and excited-atom distributions over the energetically allowed values of the principal quantum number n are obtained. Simulations of these distributions suggest that excitation of dissociative continua of bound 1 ⌺ g ϩ (1s g )(ns g ), 1 ⌺ g ϩ (1s g )(nd g ), and 1 ⌸ g (1s g )(nd g ) Rydberg states may dominate over excitation of dissociative doubly excited 1 ⌺ g ϩ (2p u )(np u ) and 1 ⌸ g (2p u )(np u ) states when considering the dissociation dynamics after one-photon absorption from the vЈу9 levels of the B-state.

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