1. THE USE OF CAAARS (Computer Aided Assignment of Asymmetric Rotor Spectra ) IN THE ANALYSIS OF ROTATIONAL SPECTRA. (CAAARS) Ivan R. Medvedev, Manfred Winnewisser, Brenda P. Winnewisser, Frank C. Delucia And Eric Herbst Department of Physics, The Ohio State University, Columbus, OH 43210

2. Computer Aided Assignment of Asymmetric Rotor Spectra (CAAARS) Journal of Molecular Structure, 742, 1-3, 229 http://www.physics.ohio-state.edu/~medvedev/caaars.htm

3. FASSST spectrum ~50000 peaks http://www.physics.ohio-state.edu/~medvedev/caaars.htm

4. FASSST Spectrum of Diethyl Ether trans-gauche b-type r Q 10 branch trans-trans b-type r Q 7 branch

5. 4. Run the fitting and prediction programs to to make new predictions.  SPFIT/SPCAT  ASFIT/ASROT 1. Make an initial prediction of the spectrum. 2. Search the experimental data for matching patterns. 5. Repeat steps 2, 3 and 4. 3. Update the assigned line list. Steps of the assignment process:

6. trans-gauche diethyl ether b-type transitions http://www.physics.ohio-state.edu/~medvedev/caaars.htm

7. Common parameters for a near prolate asymmetric rotor “branch”: 1. Transition type (a,b,c) 2.  K a 3.  J 4. K a 5. J - K a - K c (asymmetry component) http://www.physics.ohio-state.edu/~medvedev/caaars.htm

8. Computer Aided Assignment of Asymmetric Rotor Spectra (CAAARS) assignment window

9. Branch selection

11. Loomis-Wood diagram

13. Spectral assignment

15. Execution of the Fitting and Prediction Programs

17. Loading of the New Predictions

19. Features of CAAARS  Point and click approach to line assignment  The flexible sorting principle makes CAAARS applicable to a wide range of spectroscopic problems  The organization of the predicted and assigned lines into branches allows the user to plot easily Fortrat diagrams, intensity plots, R- or P-branch clusters, (K a or K c vs. frequency for a given J), errors, reduced energy plots, perturbed branch behavior, and whatever else is found useful for a given spectrum.  Assignment capabilities of CAAARS are enhanced with Loomis-Wood representation of spectra

20. Journal of Molecular Structure, 742, 1-3, 229 http://www.physics.ohio-state.edu/~medvedev/caaars.htm