Encoding of vinylidene isomerization in its anion photoelectron spectrum

Jessalyn A DeVine; Marissa L Weichman; Benjamin Laws; Jing Chang; Mark C Babin; Garikoitz Balerdi; Changjian Xie; Christopher L Malbon; W Carl Lineberger; David R Yarkony; Robert W Field; Stephen T Gibson; Jianyi Ma; Hua Guo; Daniel M Neumark

doi:10.1126/science.aao1905

Encoding of vinylidene isomerization in its anion photoelectron spectrum

Science. 2017 Oct 20;358(6361):336-339. doi: 10.1126/science.aao1905.

Authors

Affiliations

¹ Department of Chemistry, University of California, Berkeley, CA 94720, USA.
² Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia.
³ Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610067, China.
⁴ Departmento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid (Unidad Asociada I+D+I CSIC), 28040 Madrid, Spain.
⁵ Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, NM 87131, USA.
⁶ Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA.
⁷ JILA and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309, USA.
⁸ Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
⁹ Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, Sichuan 610067, China. majianyi81@163.com dneumark@berkeley.edu.
¹⁰ Department of Chemistry, University of California, Berkeley, CA 94720, USA. majianyi81@163.com dneumark@berkeley.edu.
¹¹ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.

PMID: 29051373
DOI: 10.1126/science.aao1905

Abstract

Vinylidene-acetylene isomerization is the prototypical example of a 1,2-hydrogen shift, one of the most important classes of isomerization reactions in organic chemistry. This reaction was investigated with quantum state specificity by high-resolution photoelectron spectroscopy of the vinylidene anions H₂CC- and D₂CC- and quantum dynamics calculations. Peaks in the photoelectron spectra are considerably narrower than in previous work and reveal subtleties in the isomerization dynamics of neutral vinylidene, as well as vibronic coupling with an excited state of vinylidene. Comparison with theory permits assignment of most spectral features to eigenstates dominated by vinylidene character. However, excitation of the ν₆ in-plane rocking mode in H₂CC results in appreciable tunneling-facilitated mixing with highly vibrationally excited states of acetylene, leading to broadening and/or spectral fine structure that is largely suppressed for analogous vibrational levels of D₂CC.

Publication types

Research Support, Non-U.S. Gov't