1. Zeinab. T. Dehghani, A. Mizoguchi, H. Kanamori Department of Physics, Tokyo Institute of Technology Millimeter-Wave Spectroscopy of S 2 Cl 2 : A Candidate Molecule for the Detection of ortho-para Transition 1

2. Nuclear spin of 32 S 2 is zero and 35 Cl 2 is 3/2 Effective Hamiltonian : H = H ROT + H Q + H NSR H ROT : rotational term including the centrifugal distortion H Q : nuclear quadrupole interaction H NSR : nuclear spin – rotation interaction Nuclear spin coupling scheme : I 1 =I 2 =3/2, I 1 +I 2 =I, J+I=F Basis set : |JK±,(I 1 I 2 )I,F > Wang Quantum statics for 32 S 2 35 Cl 2, when K a K c = ee, oo, → I = 0, 2 para- when K a K c = eo, oe, → I = 1, 3 ortho- Theoretical Treatments for 32 S 2 35 Cl 2 C2C2 2

3. “ortho-para” interaction appearing in the lowest rotational states? 1 11 0 00 00 22 01 22 23 21 I,FI,F 2 12 1 10 12 32 I,FI,F 1 01 J KaKc para- ortho- [1] Mizoguchi,et al., J.M.S (2008) 3 Off-diagonal terms of nuclear quadrupole interaction

4. Nuclear Quadrupole interaction 4 Field gradient tensor

5. Nuclear Quadrupole Coupling Constants of S 2 35 Cl 2 [MHz] [3] http://chemapps.stolaf.edu/jmol/jmol.php?model=ClSSCl a b c a b c a b c Cl - S bond direction is helically-tilted against all three principal axes 5 [1] Mizoguchi, et al., J.M.S (2008) View from a-, b-, c-axis [3]

6. How “ortho-para” transition can be possible? 6 [2] Zeinab, J. Phys. Chem. A, (2013)

7. |Ci||Ci| E+E+ E-E- O+O+ O-O- para ortho E+E+ E-E- O+O+ O-O- Excluding the off- diagonal terms Eigen-Vectors of the hyperfine-rotational States: F=9 (150x150 matrix) 7

8. Eigen-Vectors of hyperfine-rotational State: F=9 (150x150 matrix) |Ci||Ci| E+E+ E-E- O+O+ O-O- E+E+ E-E- O+O+ O-O- para ortho Including the off- diagonal terms  ab,  bc,  ac 8

9. Relation between interacting levels 0.002256.71 0.311.12 Candidate States for Observing “ortho-para” Transition in S 2 Cl 2 Example of two types of mixed levels Normal transition Frequency (MHz) Intensity (a.u.) Forbidden transition Offset Freq. from the normal transition(MHz) Intensity (a.u.) 81119.9431.481.129.76 70059.6016.441.202.79 9

10. ortho-para Transitions among K-doubling States | 10 7 4 1 10 > | 9 6 3 1 9 > | 8 5 4 1 8 > | 10 7 3 0 10 > | 9 6 4 0 9 > | 8 5 3 0 8 > 70 GHz 1.12 MHz ortho-states para-states 81,119.77 MHz 10 81,118.65 MHz

11. Spectrum Pattern Predicted for the Transition 11 0 2 |10 73 > P - |9 64 > P |10 74 > O - |9 63 > O

12. 200K 20K 2K [cm -1 ] Rotational Term Values and Thermal Population of S 2 Cl 2 K K-doubling | 9 6 4 >,| 9 6 3 > 12 Accidental Neighbor | 11 47 >, | 10 56 > A = 0.184cm -1 B = 0.046cm -1 C = 0.041cm -1

13. Temperature Dependence of the Rotational Spectra T=200K 20K 2K 0 20 40 60 80 [GHz] 100 13

14. Temperature Dependence of the Rotational Spectra(expanded) 200K 20K 2K 80.0 80.5 81.0 81.5 [GHz] 14

15. 15 Rapid Scanning mm-MW Pulse Jet Spectroscopy S 2 Cl 2 /(He or Ar) P = 0.5 atm InSb/He detector Pulse valve Elliptical mirror f 1 =480 f 2 =400 10” diffusion pump MW t T sweep =10ms RF Lock-in amp Source Mod. f m =100 KHz  = 0. 1 ms f sweep = 10 MHz  f = f sweep /(T sweep /  =10M/(10/0.1) = 0.1MHz 1)Pulse valve 3)MW freq. sweep 4)Molecular absorption 2)Molecules at probing region

16. Current Status of the ortho-para Transition Survey Experiment 0.01 0.6 1MHz 16 Observed Predicted

17. Summary Some candidates of the ortho-para transitions of S 2 Cl 2 are predicted with intensities. Experiment for survey of the ortho-para transition has begun. More precise prediction of the intensity, and more measurement is necessary. 17

18. 18

19. Spectrum pattern predicted for the transition 19