1. Molecular Spectroscopy Symposium 2013 17-21 June 2013 Identification and Assignment of the First Excited Torsional State of CH 2 DOH Within the o 2, e 2 and o 3 Torsional Levels John C. PEARSON, Shanshan YU Jet Propulsion Laboratory, California Institute of Technology Laurent H. COUDERT LISA, CNRS/Universités Paris Est et Paris Diderot L. MARGULÈS, R.A. MOTIYENKO Laboratoire PhLAM, Université des Sciences et Technologies de Lille S. KLEE, Physikalisch-Chemisches Institut, Justus-Liebig-Universität

2. 2 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Motivation Theory of Asymmetric-Top Asymmetric-Frame internal rotation is in its infancy –Three ground state examples HCOOCH 2 D, CH 3 CH 2 OH, CH 2 DOH all that exists –CH 2 DOH has large effects and a comprehensive IR and MW data set CH 2 DOH was first discovered in the ISM by Jacq et al., 1993, A&A 271, 276 CH 3 OH is often optically pumped (Far infrared thermal dust emission pumps the torsional bands) –CH 2 DOH should also be similarly excited Issues remain in the abundance of CH 2 DOH relative to CH 3 OD –CH 2 DOH is greatly enriched after cold processing –CH 3 OD is equally abundant to CH 2 DOH in Orion KL!  Quasi-liquid phase on evaporating grains???  Something we don’t know (i.e. partitioning wrong due to pumping?)

3. 3 Molecular Spectroscopy Symposium 2013 17-21 June 2013 C s symmetry; All wave functions are even (A’ or e) or odd (A” or o) Torsion characterized by number of nodes; Ground state e 0, e 1 and o 1, v t =1 o 2, e 2 and o 3 e to e a-type or b-type o to o a-type or b-type e to o c-type or x-type ( x is  K a =even &  K c =even) o to e c-type or x-type ( x is  K a =even &  K c =even) All are observed; e 0 -e 1 a-types are weak and the x-types generally require mixing OC H H H D Symmetry and Selection Rules

4. 4 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Spectroscopy Last year we reported the ground state (Pearson, Yu & Drouin, J. Mol. Spectrosc. 280, 119 (2012). –Term values to e 0 K a =10, e 1 K a =9 and o 1 K a =9 determined – a R branches to K a =11 identified for all states –Nearly complete spectrum 60- 1200 GHz Last year we also reported identification and assignment of 76 torsional sub- bands (El Hilali, Coudert, Konov, & Klee, J. Chem. Phys. 135, 194309 (2011). –Complete Far-IR 30-800 cm -1 spectrum The combination of calculated band origins, some assigned Q-branches, and microwave accuracy ground state term values provided a basis for assignments –Torsion effects much large in excited states so THz spectra needed

5. 5 Molecular Spectroscopy Symposium 2013 17-21 June 2013 New Data Microwave Spectra recorded in 1310-1425, 1425-1600, 1600-1800, 1760-2010 & 2450-2700 GHz regions at JPL & Lots of unassigned lines in previous data o 1 K=11 to e 1 K=10 Q

6. 6 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Assignments Boot-strap assignments of ground state –Identified Q-branches connecting ground state to e 0 K=14, e 1 K=13 and o 1 K=13 –Confirmed previous a R-branch assignments –Identified a R-branches to e 0 K=14, e 1 K=13 and o 1 K=13 –Checked assignments with multiple loops from other Q branches  6 Q branches are possible for each K a value in each state –Only issue identified is weak perturbation in e 1 K=12 @ J=20 Fit all the new bands with power series model –B*J(J+1)-D*[J(J+1)] 2 +H*[J(J+1)] 4 +…. –e 1 K=12 fit with 4 J’s weighted out Unidentified strong lines are excited torsional states! –Many Q-branches were easily located –P/R branches on series of very strong lines

7. 7 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Ground-State Torsional Structure There is a real difference in e 1 /o 1 relative to e 0 (B+C)/2 is significantly smaller in e 1 /o 1 A is slightly smaller in e 1 /o 1

8. 8 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Microwave Assigned Band K=0 K=1 K=2 K=3 K=4 K=5 K=6 K=7 K=8 K=9 o2 e2 o3 2253 1706 47 aR branch assigned and confirmed aR branch assignment only not assigned P, Q and/or R in spectrum Number is calculated Q origin Branch confirmed with loops

9. 9 Molecular Spectroscopy Symposium 2013 17-21 June 2013 IR Bands Assigned K=0 K=1 K=2 K=3 K=4 K=5 K=6 K=7 K=8 K=9 o2 e2 o3 e0 e1 o1

10. 10 Molecular Spectroscopy Symposium 2013 17-21 June 2013 v t =1 Structure Internal rotation is still hindered especially in o 2, but becomes nearly free rotor thereafter

11. 11 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Interaction of o 2 K=0 and K=2 o 2 K a =2 K c =J-1 o 2 K a =0 or 2, K c =J or J-2 o 2 K=1 e 2 K=0 K a =0, K c =J is completely mixed with K a =2 K c =J-2 due to asymmetry Extra bands are observed in all cases, asymmetry splitting is enormous

12. 12 Molecular Spectroscopy Symposium 2013 17-21 June 2013 The 4-state interaction o 3 K=3, o 3 K=2, e 2 K=4 & o 3 K=1 K=2 of o 3 remains unconnected. It will reside between e 2 K=4 and o 3 K=3. There will be a D ab interaction with o 3 K=3. No crossing to J=23

13. 13 Molecular Spectroscopy Symposium 2013 17-21 June 2013 e 2 K=8 and e 1 K=12 Interaction has x-symmetry (  K a =4,  K c =4) and is very weak (d 1 = 8.4622(59) x10 -4 MHz fits the data) Probably only allowed due to mixing {i.e. a-type Coriolis between o 1 and e 1 (0,1) and a-type Coriolis between e 2 and o 1 (4,3/5)}

14. 14 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Future Work Finish IR assignments connecting e 0, e 1, o 1, o 2, e 2, and o 3 Connect o 3 K=2 to the rest of the levels (3 possible bands) –More will be allowed by mixing Assign higher K a values in o 2, e 2 and o 3 Add IR bands involving e 3, e 4 and o 4 –Identify a R-branches confirming assignments with loops –Identify microwave P,Q, & R branch connections –Understand why o 3 K=8 is asymmetry Add IR bands involving o 5, e 5, o 6 and e 6 –Identify a R-branches confirming assignments with loops Assign the rest of the IR spectrum

15. 15 Molecular Spectroscopy Symposium 2013 17-21 June 2013 Acknowledgements Support for part of this work, part of the NASA Herschel Science Center Theoretical Research/Laboratory Astrophysics Program, was provided by NASA through a contract issued by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA." Part of this work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration