Rotationally Resolved State-to-State Photoelectron Study of Molybdenum Monoxide Cation (MoO+)

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Detail(s)

Original languageEnglish
Pages (from-to)4643-4654
Journal / PublicationJournal of Physical Chemistry A
Volume120
Issue number27
Online published1 Oct 2015
Publication statusPublished - 14 Jul 2016

Abstract

By employing the two-color visible-ultraviolet (vis-UV) laser pulsed field ionization-photoelectron (PFI-PE) measurement, we have obtained rotationally selected and resolved photoelectron spectra for the MoO+(X4- v+ = 0, 1, and 2) and MoO+(a2Δ3/2,5/2; v+ = 0 and 1) cationic states. The unambiguous rotational assignments have made possible the determination of highly precise values for the band origin v00+ = 60 147.9 ± 0.8 cm-1, rotation constant B0+ = 0.4546 ± 0.0006 cm-1, spin-spin coupling constant λ = 26.454 ± 0.017 cm-1, and bond length re+ = 1.642 ± 0.001 Å for the MoO+(X4-) ground state; v00+ = 60 556.4 ± 0.8 cm-1, B0+ = 0.4711 ± 0.0005 cm-1, and r0+ = 1.613 ± 0.001 Å for the MoO+ (a2Δ3/2) excited state; and v00+ = 61 718.2 ± 0.8 cm-1, B0+ = 0.4695 ± 0.0006 cm-1, and r0+ = 1.616 ± 0.001 Å for the MoO+ (a2Δ5/2) excited state. The ionization energy (IE) for MoO is determined to be IE(MoO) = 60 095.1 ± 0.8 cm-1 [7.4508 ± 0.0001 eV]. Furthermore, the vibrational constants are determined as ωe+ = 1000 ± 9 cm-1 and ωe+xe+ = 5 ± 3 cm-1 for MoO+(X4-); the vibration spacing ΔG(1/2) for MoO+(a2Δ3/2) is also measured as 1065 ± 4 cm-1. On the basis of the thermochemical cycle, together with the known IE(Mo) and the IE(MoO) determined in this study, the difference of 0 K bond dissociation energy for MoO+ and that for MoO is determined to be D0(Mo+-O) - D0(Mo-O) = IE(Mo) - IE(MoO) = -2890.8 ± 0.9 cm-1 [-0.3584 ± 0.0001 eV]. The energetic and spectroscopic values determined here have been used for benchmarking calculations at the CCSDTQ/CBS level of theory. The CCSDTQ/CBS predictions, IE(MoO) = 7.457 eV, re+ = 1.651 Å, ωe+ = 974 cm-1, D0(Mo-O) = 5.386, and D0(Mo+-O) = 5.015 eV, are found to be in good agreement with the vis-UV PFI-PE measurements. We also recommend a set of equally reliable CCSDTQ/CBS thermochemical values for MoO and MoO+: ΔH°f0(MoO) = 383.7, ΔH°f298(MoO) = 384.0, ΔH°f0(MoO+) = 1103.2, and ΔH°f298(MoO+) = 1103.5 kJ mol-1.

Citation Format(s)

Rotationally Resolved State-to-State Photoelectron Study of Molybdenum Monoxide Cation (MoO+). / Luo, Zhihong; Chang, Yih-Chung; Pan, Yi; Lau, Kai-Chung; Ng, C. Y.

In: Journal of Physical Chemistry A, Vol. 120, No. 27, 14.07.2016, p. 4643-4654.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review