Resonance-enhanced multiphoton ionisation spectroscopy of the NH(ND) radical. Part 1?The d 1?+ state (original) (raw)
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The Journal of Physical Chemistry, 1988
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.
The Journal of Physical Chemistry, 1987
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 spectra of the GeF and GeCl radicals from 400 to 500 nm
Journal of Chemical Physics, 1988
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.
Ultraviolet photodissociation of OCS: Product energy and angular distributions
The Journal of Chemical Physics, 2013
The ultraviolet photodissociation of carbonyl sulfide (OCS) was studied using three-dimensional potential energy surfaces and both quantum mechanical dynamics calculations and classical trajectory calculations including surface hopping. The transition dipole moment functions used in an earlier study [J. A. Schmidt, M. S. Johnson, G. C. McBane, and R. Schinke, J. Chem. Phys. 137, 054313 (2012)] were improved with more extensive treatment of excited electronic states. The new functions indicate a much larger contribution from the 1 1 A state ( 1 − in linear OCS) than was found in the previous work. The new transition dipole functions yield absorption spectra that agree with experimental data just as well as the earlier ones. The previously reported potential energy surfaces were also empirically modified in the region far from linearity. The resulting product state distributions P v,j , angular anisotropy parameters β(j), and carbon monoxide rotational alignment parameters A (2) 0 (j ) agree reasonably well with the experimental results, while those computed from the earlier transition dipole and potential energy functions do not. The higher-j peak in the bimodal rotational distribution is shown to arise from nonadiabatic transitions from state 2 1 A to the OCS ground state late in the dissociation. to 130.225.101.2. Redistribution subject to AIP license or copyright; see http://jcp.aip.org/about/rights\_and\_permissions 094314-2 McBane et al.
Multi-Coincidence Studies of Fragmentations of Core Excited OCS Molecules
Acta Physica Polonica A, 1997
Molecular fragmentation following photon excitation of core electrons from K shells of C and O and L shell of S atoms forming the OCS molecule was studied. Emerging photoelectrons and charged fragments were detected in coincidence. Application of time-of-flight spectroscopy together with triple coincidence photoelectron-photoion-photoion, double coincidence photoelectron-photoion and photoion-photoion techniques allow a detailed insight into the geometry and the dynamics of the de-excitation processes and an unambiguous assessment of all fragmentation channels of highly excited molecules. Such studies are of major interest in fundamental research and they are relevant also in environmental, biological and technological investigations.
The 157 nm photodissociation of OCS
The Journal of Chemical Physics, 1989
The photodissociation ofOeS at 157 nm has been investigated by using tunable vacuum ultraviolet radiation to probe the eo and S photoproducts. Sulfur is produced almost entirely in the IS state, while eo is produced in its ground electronic state and in vibrational levels