Spectroscopy of NCNCS at the Canadian Light Source: the far-infrared spectrum of the ν 7 region from cm -1 (and beyond…) Dennis W. Tokaryk, Stephen C. Ross Department of Physics and Centre for Laser, Atomic, and Molecular Sciences University of New Brunswick, Fredericton, NB Canada Brenda Winnewisser, Manfred Winnewisser, F. C. De Lucia Department of Physics, The Ohio State University, Columbus, OH USA Brant E. Billinghurst Canadian Light Source, Inc., Saskatoon, SK Canada 69 th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014

Background: the energy-momentum map of NCNCS presented in the previous talk has been calculated, not measured. Generate parameters describing the potential by fitting B eff, D eff from each rotational vb/Ka series. Calculate energies from fitted potential

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Objective: to measure the (v b, J=K a ) levels on this map relative to one another using the far-infrared rotation-vibration spectra obtained at the CLS

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Objective: to locate the (v b, J=K a ) levels on this map relative to one another using the far-infrared rotation-vibration spectra obtained at the CLS b-type sub-bands a-type sub-bands

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 1: the spectrum of the ν 7 low-frequency high-amplitude bending mode

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 1: the spectrum of the ν 7 low-frequency high-amplitude bending mode v b 1-0 K a = 0 An Interactive Loomis-wood Package for Spectral Assignment in Igor Pro. Neese, C. F. Fifty-sixth Ohio State University International Symposium on Molecular Spectroscopy Columbus, Ohio, June 11-15, 2001.

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 1: the spectrum of the ν 7 low-frequency high-amplitude bending mode Mask Data Correlation spectrum

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 1: the spectrum of the ν 7 low-frequency high-amplitude bending mode Up to K a = 10 K a = 12 Origins of 68 a-type sub-bands of the ν 7 spectrum determined in ~1.5 hours with the correlation procedure! But no b-type sub-bands were found… : (

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 2: the spectrum of the ν 3 hybrid band stretching mode PGOPHER, a Program for Simulating Rotational Structure, C. M. Western, University of Bristol, a-type sub-bands b-type sub-bands

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 2: the spectrum of the ν 3 hybrid band stretching mode KaKa KaKa K a +1 K a -1 ν 3 =1 ν 3 =0 v 3 K a = 6 a-type identify a-type sub-bands the hard way for a given value of K a. calculate term energies in the ν 3 level. create mask spectrum from upper state term energies and calculated levels for v=0, K a ±1. correlate the mask spectrum with the data.

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Phase 2: the spectrum of the ν 3 hybrid band stretching mode K a ’-K a ’’

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 The energy-momentum map so far… Up to K a = 10 K a = 12 The relative energy of all states connected by arrows are now known…. : ) But the stacks with K a =0 and K a =1 still float relative to the others… : (

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Where to next? FAAAST Rotational spectrum: correlator failed to turn up the b-type sub- bands that would connect K a 1-0 and 2-1. Hybrid bands in cm -1 range: lots of b-type Q-branches among the a-type spectra. The data potentially contain the two missing connections needed to complete the energy-momentum map.

69th International Symposium on Molecular Spectroscopy Champaign-Urbana, IL USA June 19, 2014 Conclusions A directly measured energy-momentum map for the bending mode of NCNCS is nearly complete! The potential function for the bending motion, obtained by fitting only B eff and D eff constants from pure rotational data with Stephen Ross’ Generalized Semi- Rigid Bender program, predicted vibrational level positions relative to one another to within ~2 cm -1 (for the levels I’ve checked – not an exhaustive list). The physics that underlies quantum monodromy imprints itself on the large-amplitude bending motion (and a wide selection of other physical properties) of molecules… … and the GSRB Hamiltonian captures that physics very nicely. (DWT thanks Damien Forthomme and Colin Sonnichsen for help with the experiments, and NSERC for research funds.)

Welcome to the world where vibration and rotation can not be separated and the eigenfunctions can not be factored: Dynamics of large amplitude motion Quantum monodromy in a Champagne bottle potential function