Attempts At Using IAMCALC to Analyze Low Frequency

Attempts At Using IAMCALC to Analyze Low Frequency Rotational Spectra of Molecules With Internal Rotation And Nuclear Spins C. T. Dewberry, S. A. Cooke

Outline �Interest �Internal Rotation �Programs � General Description � Quadrupole Coupling � New Data � Independent IAMCALC Fit �Concluding Remark Molecules Discussed • • Butyronitrile Acetyl chloride Methanol isotopologues (New Data) Methyl Nitrite (New Data)

Interest (Gauche n-Butyronitrile) �Saw internal rotation �Study larger molecules (amino acids, peptides) Threonine 562. 4 MHz 12000 Cycles Alanine

Experiment �Used the Low Frequency FTMW Spectrometer �CP-FTMW Spectrometer (RC 06)

Internal Rotation

• Characterization – “No other type of spectrum is nearly as unique and characteristic as a microwave spectrum”. • Nuclear Quadrupole Fine Structure – “… analysis of spectral patterns gives information about the electron distribution (and bonding) within a molecule”. • Barriers to Internal Rotation – “… is an area in which microwave spectroscopy has had a major and almost unique contribution”. • Centrifugal Distortion and Chemical Bonds – “… it becomes possible to use the deviations from the rigid rotor fit to learn about the valence forces in a quantitative way”. • Magnetic Effects (Hyperfine Structure) – “… yield some very detailed information about the way in which the electrons are distributed in the molecule”. • Testing Theories – “Since microwave spectroscopy is capable of providing refined information about electrons in molecules, it is serving more and more as the basis for severe tests of current theories”.

Fitting Programs for Internal Rotation

Programs for Internal Rotation • • Belgi (Isabel Kleiner) + Established + Intuitive coding (after initial learning) XIAM (Holger Hartwig) + Established + Very well documented + Very fast Calculations + Can solve for Quadrupole Coupling ~ Uses several parameters - Several Different Versions - Can’t solve for Quadrupole Coupling ~ Uses minimal parameters - Program can bog down if not careful - Difficulty reproducing results (for me) • IAMCALC (Herb Pickett) + Can use a small or large list of parameters + Can solve for Quadrupole Coupling + Results can be repeated if careful, but variations can still be expected • ERHAM (Peter Groner) ~ I Haven’t worked with this one yet ~ New - Not documented (but uses SPFIT/SPCAT) - Semi Steep learning Curve - Calculations can take a very long time I. Kleiner, J. Mol. Spec. 260, 1, 2010

Quadrupole Coupling

Acetyl Chloride �Used to help with benchmarking �Used to help determine the use of quadrupole coupling for the IAM CALC program 8 -10 GHz 30000 cycles 8340 8860 MHz 9380 9900

XIAM 8610 8620 MHz 8630 K. M. Sinnott, J. Chem Phys. 34, 3, 1961

IAMCALC _ 8620 8630 _ _ 8610 MHz K. M. Sinnott, J. Chem Phys. 34, 3, 1961

IAMCALC �Attached the χ tensors at the end of a. iam file for quadrupole coupling constants _ 8620 8630 _ _ 8610 MHz K. M. Sinnott, J. Chem Phys. 34, 3, 1961

Comparison for Acetyl Chloride XIAM IAMCALC A B C ΔJ Δ JK δj δk F V 3 ρ χ aa χ bb χ cc Previous Fit M. Hayashi et al. (1995) 10162. 424 4946. 704 3393. 064 2. 14 E-03 5. 29 E-03 6. 01 E-04 3. 81 E-03 1. 57 E+5 1. 326 E+7 0. 03514128 -58. 237 36. 493 21. 944 10162. 390 4946. 757 3393. 020 2. 89 E-03 8. 24 E-03 8. 11 E-04 -2. 29 E-04 1. 46 E+05 9. 52 E+06 0. 02670922 -58. 676342 36. 305862 22. 37048 10162. 337 4946. 777 3393. 014 2. 08 E-03 8. 66 E-03 9. 82 E-04 -1. 19 E-03 1. 59 E+04 5. 01 E+05 0. 01519991 -57. 926107 36. 1706543 21. 7554529 n rms 26. 095 MHz 152. 352 MHz 152. 783 MHz

New Data For Previously Studied Simple Internal Rotors

Methanol Isotopologues �Used existing data from previous works and our own measurements �Had difficulty fitting to all observed transitions �We want to account for interaction between internal rotation and nuclear spin (Dymanus) 834. 4 MHz 22561 Cycles

Methanol Transitions A symmetry transitions of methanol Frequency Transition Uncertainty (MHz) Unassigned 834. 2521 0. 0020 4 1 1 0 1 ← 1 1 1 2 834. 2640 0. 0020 8 1 1 0 2 ← 1 1 1 2 834. 2837 0. 0020 8 1 1 0 1 ← 1 1 834. 2945 0. 0020 8 1 1 0 2 ← 1 1 834. 3026 0. 0020 5 Unassigned 834. 3143 0. 0020 5 Unassigned 2384. 0499 0. 0020 5 2 1 1 2 ← 2 1 2 3 2502. 7605 0. 0100 5 2 1 1 3 ← 2 1 2 3 2502. 7782 0. 0020 5 2 1 1 2 ← 2 1 2 2 2502. 7931 0. 0100 5 2 1 1 3 ← 2 1 2 2 2502. 8060 0. 0100 6 3 1 2 4 ← 3 1 3 4 5005. 3195 0. 0020 7 5 1 5 6 ← 6 0 6 7 6668. 5198 0. 0020 7 Transition 1 3 2 7 2 7 2 4 2 4 2 3 1 4 1 5 1 6 5← 9← 8← 9← 6← 5← 5← 6← 6← 5← 7← 8← 7← 4 9 9 9 4 4 5 5 6 7 7 1 4 1 8 1 8 3 1 3 1 3 2 1 5 1 6 1 7 5 10 9 9 5 4 5 5 6 5 7 8 7 Frequency (MHz) 8341. 6133 9936. 1833 9936. 2002 9936. 2203 9978. 6750 9978. 6888 9978. 7071 10058. 2615 12511. 1976 12511. 2093 17513. 3368 23346. 9220 23346. 9761 Uncertainty 0. 0020 0. 0100 0. 2000 0. 0400 0. 0100 0. 0050 0. 0300

Methanol-OD 1249. 7 MHz 14400 Cycles

Methanol-OD Transitions A symmetry transitions of methanol-OD Frequency Transition Uncertainty (MHz) 1 1 0 1 ← 1 1 1360. 2369 0. 002 10 1 1 0 2 ← 1 1 1360. 2469 0. 002 10 1 1 0 0 ← 1 1 1360. 2768 0. 002 10 1 1 0 2 ← 1 1 1 2 1360. 3174 0. 002 3 7 2 5 7 ← 7 2 6 7 1485. 1241 0. 002 3 7 2 5 8 ← 7 2 6 8 1485. 1382 0. 002 3 8 2 6 8 ← 8 2 7 8 2470. 0084 0. 002 11 8 2 6 9 ← 8 2 7 9 2470. 0265 0. 002 11 9 2 7 9 ← 9 2 8 9 3870. 1036 0. 005 11 9 2 7 10 ← 9 2 8 10 3870. 1282 0. 005 11 2 1 1 2 ← 2 1 2 2 4080. 6581 0. 002 12 2 1 1 2 ← 2 1 2 3 4080. 7061 0. 002 12 2 1 1 2 ← 2 1 4080. 7326 0. 002 4 2 1 1 3 ← 2 1 2 3 4080. 7797 0. 002 4 2 1 1 1 ← 2 1 2 2 4080. 8254 0. 002 4 2 1 1 1 ← 2 1 4080. 8629 0. 002 5 3 0 3 3 ← 2 1 2 2 4811. 8077 0. 002 5 3 0 3 4 ← 2 1 2 3 4811. 8805 0. 002 5 3 0 3 2 ← 2 1 4811. 9200 0. 002 Transition 2 8 2 8 1 2 1 2 2 9 2 9 2 10 1 3 1 3 1 4 1 4 10 11 9 3 4 2 11 11 11 12 12 13 4 5 3 5 6 4 ← ← ← ← ← 10 10 10 3 3 3 11 11 12 12 4 4 4 5 5 5 2 9 2 9 1 3 1 3 2 10 2 11 1 4 1 4 1 5 1 5 10 11 9 3 3 2 10 12 11 12 12 13 4 5 3 5 6 4 Frequency (MHz) 5782. 3889 5782. 4172 5782. 4285 8160. 8803 8161. 0072 8161. 0545 8309. 6959 8309. 7038 8309. 7223 8309. 7427 11558. 2342 11558. 2670 13600. 0433 13600. 1669 13600. 2038 20396. 5519 20396. 6894 20396. 7177 Uncertainty 0. 002 0. 005 0. 002

Methanol-OD Transitions E symmetry transitions of methanol-OD Transition Frequency (MHz) Uncertainty 13 -1 13 14 ← 13 0 13 14 9681. 5509 0. 004 12 -1 12 13 ← 12 0 12 13 11357. 4563 0. 004 11 -1 11 12 ← 11 0 11 12 13027. 0026 0. 004 10 -1 10 11 ← 10 0 10 11 14585. 7563 0. 004 3 2 1 4 ← 4 1 3 5 14920. 3981 0. 002 9 -1 9 10 ← 9 0 9 10 15948. 1628 0. 004 8 -1 8 9 ← 8 0 8 9 17057. 0900 0. 030 7 -1 7 8 ← 7 0 7 8 17888. 7011 0. 050 6 -1 6 7 ← 6 0 6 7 18454. 6838 0. 050 5 -1 5 6 ← 5 0 5 6 18792. 8436 0. 050 4 -1 4 5 ← 4 0 4 5 18957. 8134 0. 010 1 -1 1 2 ← 1 0 1 2 18958. 0447 0. 004 2 -1 2 3 ← 2 0 2 3 18991. 5874 0. 050 3 -1 3 4 ← 3 0 3 4 19005. 5792 0. 050 1 1 0 2 ← 2 0 2 3 19519. 0612 0. 002

Methanol-D 4 2573. 3 MHz 5000 Cycles

Methanol-D 4 Transitions A symmetry transitions of methanol-D 4 Frequency Transition (MHz) 1 8 8 2 2 2 2 9 9 9 3 3 1 1 1 0 2 6 1 1 1 1 2 7 2 7 1 2 1 2 1 1 1 1 1 5 11 12 4 5 5 3 6 6 4 5 12 13 11 6 4 7 5 5 5 4 4 3 ← ← ← ← ← ← 1 8 8 2 2 2 2 9 9 9 3 3 2 2 2 1 1 2 7 1 2 1 2 2 8 2 8 1 3 1 3 0 2 0 2 0 2 5 11 12 5 6 5 4 5 6 3 4 12 13 11 6 5 7 4 5 6 4 5 2 857. 8794 1781. 6704 1781. 6887 2573. 403 2573. 4399 2573. 4575 2573. 4784 2573. 4978 2573. 5229 2573. 5699 2573. 5878 2777. 6407 2777. 7469 2777. 7777 5146. 5132 5146. 5696 5146. 6381 5146. 6866 8147. 5015 8147. 6164 8147. 6644 8147. 6891 8147. 7560 Uncertainty 0. 002 0. 004 0. 002 Transition 4 4 5 5 5 3 3 6 6 6 3 3 3 1 3 1 3 1 5 1 4 1 4 2 2 2 2 1 5 1 5 2 1 2 1 7 ← 4 8 ← 4 5 ← 4 6 ← 4 9 ← 4 8 ← 4 Unassigned 8 ← 5 9 ← 5 7 ← 5 5 ← 4 7 ← 4 6 ← 4 4 ← 4 9 ← 6 10 ← 6 8 ← 6 5 ← 4 7 ← 4 6 ← 4 1 4 1 4 2 2 1 5 1 5 1 3 1 3 1 6 1 6 1 4 1 4 7 8 5 6 8 7 8 9 7 6 8 7 5 9 10 8 6 8 7 Frequency (MHz) Uncertainty 8576. 4056 8576. 5324 8576. 5518 8576. 5652 11738. 4988 11738. 5232 11755. 0272 12861. 6561 12861. 7843 12861. 8132 14172. 8224 14172. 8462 14172. 8787 14172. 9754 17999. 7107 17999. 8384 17999. 8602 22791. 9809 22792. 0576 22792. 1279 0. 002 0. 004 0. 002 0. 010 0. 200 0. 004 0. 002 0. 004 0. 007 0. 040

Methanol-D 4 E symmetry transitions of methanol-D 4 Transition Frequency (MHz) Uncertainty 9 2 7 12 ← 9 2 8 12 16571. 3620 0. 004 9 2 7 13 ← 9 2 8 13 16571. 4660 0. 004 9 2 7 11 ← 9 2 8 11 16571. 9671 0. 060 7 4 4 11 ← 8 3 6 12 20207. 4069 0. 007 9 3 7 13 ← 10 14 20256. 2573 0. 010

Independent IAMCALC Fit Compared to Previous Work

Methylnitrite (Cis) �Isabelle Kleiner brought to our attention (MJ 12) 19920. 0 MHz 400 Cycles

Methyl nitrite (Cis) IAMCALC A B C ΔJ Δ JK ΔK δj δk F V 3 ρ χ aa χ bb χ cc Previous Fit P. N. Ghosh et al. (1980) 20272. 540 7437. 914 5630. 582 6. 74 E-03 -12. 90 E-03 54. 97 E-03 2. 1 E-03 5. 4 E-03 1. 59 E+05 2. 20 E+07 0. 08411 1. 443 -4. 874 3. 431 n 31 36 20272. 539 7437. 911 5630. 582 6. 75 E-03 -12. 89 E-03 54. 98 E-03 2. 1 E-03 5. 4 E-03 1. 40 E+05 8. 13+06 0. 01326 1. 345 -3. 831 2. 486

Conclusion �Can use IAM CALC to simultaneously account for quadrupole coupling and internal rotation �Observed new transitions for Methanol-OD, Methanol-D 4, and Methyl nitrite �Need a program to account for the interaction between internal rotation and quadrupole coupling

Future Work

Future Work �Continue work on Methanol isotopologues �Look at the ERHAM fitting program �Write code for Internal Rotation and Nuclear Spin Interaction (Based on the solution by Dynamus)

Something Extra

For the experimentalists �Used a new antenna design (Similar to a Meander line antenna) �Used to measure all the spectra for the methanol isotopologues (. 8 – 24 GHZ)

Acknowledgments �The Microwave community for making these programs freely accessible �Isabel Kleiner �The Cooke Group (Andrew Agnew) �National Science Foundation (NSF)

Methyl nitrite (Cis) IAMCALC A B C ΔJ Δ JK ΔK δj δk F V 3 ρ χ aa χ bb χ cc Previous Fit P. N. Ghosh et al. (1980) 20272. 540 7437. 914 5630. 582 6. 74 E-03 -12. 90 E-03 54. 97 E-03 2. 1 E-03 5. 4 E-03 1. 59 E+05 2. 20 E+07 0. 08411 1. 443 -4. 874 3. 431 n rms 31. 095 MHz 36. 372 MHz 20272. 539 7437. 911 5630. 582 6. 75 E-03 -12. 89 E-03 54. 98 E-03 2. 1 E-03 5. 4 E-03 1. 40 E+05 8. 13+06 0. 01326 1. 345 -3. 831 2. 486