1. ULTRAHIGH-RESOLUTION SPECTROSCOPY OF DIBENZOFURAN S 1 ←S 0 TRANSITION SHUNJI KASAHARA 1, Michiru Yamawaki 1, and Masaaki Baba 2 1) Molecular Photoscience Research Center, Kobe University, Japan 2) Graduate School of Science, Kyoto University, Japan J K c(z)c(z) J KcKc c a oblate symmetric top A=B>C b(z)b(z) near prolate asymmetric top A>B ~ C J KcKc a(z)a(z) b c

2. Motivation for the Measurement of Excited States by Doppler-Free / Sub-Doppler High Resolution Spectroscopy Rotational-resolved high-resolution spectrum in UV-VIS region Regularity of rotational lines  Molecular constants in high accuracy Anomalies of rotational lines  Line position (energy shift)  Line width (broadening)  Zeeman effect (splitting) Assignments of rotational transitions Molecular structure Dynamical process

3. Nd:YVO 4 Laser; Millenia Xs Magnet Ar gas Pulse nozzle Sample Filter UV laser Etalon marker PD I 2 cell Lock-in Amp. EOM PD Skimmer Slit(1 mm) Vac. pump PM Ring Dye Laser; CR699-29 UV Laser  Molecular Beam Single-mode Laser Absolute Wavenumber Measurement System Doubling Cavity; WavetrainSC Computer Photon Counter Accuracy 0.0001 cm -1   0.0001 cm -1 Ultrahigh-resolution UV spectroscopy in molecular beam Liq. N 2 Trap  (FWHM)  0.0005 cm -1

4. Etalon PBS PD λ/4 PZT YAG Laser Error Signal Generator 19MHz Oscillator EOM PBS Error Signal Generator 19MHz Oscillator I 2 stabilized YAG laser I 2 Cell PD PBS PC Stabilized Etalon EOM PD Laser EOM 30MHz Oscillator Frequency Marker (each 30 MHz)

5. Nd:YVO 4 Laser; Millenia Xs Magnet Ar gas Pulse nozzle Sample Filter UV laser Etalon marker PD I 2 cell Lock-in Amp. EOM PD Skimmer Slit(1 mm) Vac. pump PM Ring Dye Laser; CR699-29 UV Laser  Molecular Beam Single-mode Laser Absolute Wavenumber Measurement System Doubling Cavity; WavetrainSC Computer Photon Counter Accuracy 0.0001 cm -1   0.0001 cm -1 Ultrahigh-resolution UV spectroscopy in molecular beam Liq. N 2 Trap  (FWHM)  0.0005 cm -1

6. Chopper PBS: Polarization Beam splitter I 2 Cell PBS Laser Photo -diode Photo -diode Doppler-free absorption spectrum of I 2 Absolute wavenumber of each I 2 hyperfine line can be obtained from “Doppler-free High Resolution Spectral Atlas of Iodine Molecule 15000 to 19000 cm -1 ” in accuracy of 0.0001 cm -1.

7. Nd:YVO 4 Laser; Millenia Xs Magnet Ar gas Pulse nozzle Sample Filter UV laser Etalon marker PD I 2 cell Lock-in Amp. EOM PD Skimmer Slit(1 mm) Vac. pump PM Ring Dye Laser; CR699-29 UV Laser  Molecular Beam Single-mode Laser Absolute Wavenumber Measurement System Doubling Cavity; WavetrainSC Computer Photon Counter Accuracy 0.0001 cm -1   0.0001 cm -1 Ultrahigh-resolution UV spectroscopy in molecular beam Liq. N 2 Trap  (FWHM)  0.0005 cm -1

8. PM Magnet Laser A A B B Skimmer Pulse nozzle Sample Pole peace Slit Molecular Beam Liq. N 2 trap

9. Marker etalon (stabilized by I 2 stabilized YAG laser) Doppler-free absorption spectrum of I 2 Rotational-resolved high-resolution spectrum of Dibenzofuran Ultrahigh-resolution spectrum of 0 0 0 + 443 cm -1 band

10. S 1 ←S 0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm -1 ) dibenzofuran

11. Ultrahigh-resolution spectrum of 0 0 0 and 0 0 0 + 443 cm -1 band B-type transition A-type transition

12. Ψ 47 B1B1 Ψ 46 Ψ 45 Ψ 44 A2A2 B1B1 A2A2 Ψ 43 B1B1 Ψ 42 A2A2 HOMO LUMO 2 nd LUMO 2 nd HOMO 34087(+443 cm -1 ) 1A11A1 1 A 1 ( S 0 ) 1 B 2 ( S 2 ) 1 A 1 ( S 1 ) H vibronic A-type ΔK a = 0 B-type ΔK a =±1 E (cm -1 ) 0 33644 41000 HOMO － LUMO Electronic excited states of dibenzofuran molecule y(a)y(a) z(b)z(b) O

13. Ultrahigh-resolution spectrum of 0 0 0 and 0 0 0 + 443 cm -1 band

14. Ultrahigh-resolution spectrum of 0 0 0 band (P lines)

15. Obtained Molecular Constants of S 1 and S 0 States of dibenzofuran S 0 1 A 1 (v=0)S 1 1 A 1 (v=0) A (cm -1 )0.0759913(10)0.07527912(81) B0.02005071(65)0.01982969(29) C0.01586638(57)0.01569587(17) D K (×10 -8 )3.67(22)3.33(19) D JK (×10 -8 )-3.43(15)-3.328(70) D J (×10 -9 )5.20(27)5.374(88) δ K (×10 -7 )3.26(11)3.106(21) δ J (×10 -9 )1.79(13)2.102(49) κ -0.86091-0.86124 I a (×10 -46 kg m 2 )36.8367837.18528 IbIb 139.60976141.16584 IcIc 176.42807178.34467 ⊿ = I c - I a - I b -0.01847-0.00644 T 0 (cm -1 )-33644.347663(66) standard deviation-0.00059 fitted lines-4835 lines assigned lines-5032 lines band type -B type

16. Ultrahigh-resolution spectrum of 0 0 0 and 0 0 0 + 443 cm -1 band

17. Ultrahigh-resolution spectrum of 0 0 0 + 443 cm -1 band (Q lines)

18. S 1 ←S 0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm -1 ) dibenzofuran

19. Ultrahigh-resolution spectrum of higher vibrational band

20. Obtained Molecular Constants of S 1 and S 0 States of dibenzofuran S 0 1 A 1 (v=0)S 1 1 A 1 (v=0) S 1 1 A 1 (b 2 :v 55 =1) (0 0 0 + 443 cm -1 ) S 1 1 A 1 (0 0 0 + 857 cm -1 ) S 1 1 A 1 (0 0 0 + 1149 cm -1 ) S 1 1 A 1 (0 0 0 + 1321 cm -1 ) A (cm -1 )0.0759913(10)0.07527912(81)0.07509478(55)0.07520210(95)0.0750354(15)0.0745546(53) B0.02005071(65)0.01982969(29)0.01985611(25)0.01983592(28)0.0198581(50)0.01987367(51) C0.01586638(57)0.01569587(17)0.01571066(20)0.01570413(15)0.01570651(27)0.01571172(26) D K (×10 -8 )3.67(22)3.33(19)3.24(12)3.12(20)-2.81(41) D JK (×10 -8 )-3.43(15)-3.328(70)-3.099(58)-3.224(71)--1.099(78) D J (×10 -9 )5.20(27)5.374(88)4.826(82)5.763(61)-5.83(21) δ K (×10 -7 )3.26(11)3.106(21)2.976(27)3.474(16)-2.830(52) δ J (×10 -9 )1.79(13)2.102(49)1.628(57)1.964(34)-2.24(12) κ -0.86091-0.86124-0.86039-0.86111-0.86005-0.85854 I a (×10 -46 kg m 2 )36.8367837.1852837.2765637.2233637.3060637.54664 IbIb 139.60976141.16584141.97801141.12150140.96388140.85344 IcIc 176.42807178.34467178.17678178.25087178.22386178.14676 ⊿ = I c - I a - I b -0.01847-0.00644-0.07778-0.09399-0.04608-0.23532 T 0 (cm -1 )-33644.347663(66)34087.498758(52)34501.877194 (82)34794.46442(13)34965.918929(98) standard deviation -0.000590.000340.000540.000680.0010 fitted lines-4835 lines2904 lines2449 lines135 lines999 lines assigned lines-5032 lines3047 lines2529 lines140 lines1048 lines band type -B typeA type

21. Zeeman broadening of 0 0 0 band

22. ZS ∝ K c 2 ZS ∝ J 2 K c = 0 （ K a = J ） K c = J （ K a = 0 ） J c KcKc a m Magnetic moment is along to c-axis. (out of plane) (J, K) dependence of the observed Zeeman splittings ZS -MJ-MJ MJMJ

23. J K c(z)c(z) J KcKc a b(z)b(z) J KcKc a(z)a(z) b Zeeman interaction c(y)c(y) c(x)c(x) All these molecule, (i) the order of magnitude of Zeeman Splitting is the same. (ii) the J- and K-dependences are the same. ZS ∝ (K c ) 2, ZS ∝ J Magnetic moment is along to c-axis. (out of plane) The magnetic moment comes from the orbital angular momentum of electrons, not from the triplet state!

24. Rotationally resolved ultrahigh-resolution spectra of jet-cooled dibenzofuran (DF) for the 0 0 0 and several vibronic bands up to 0 0 0 + 1335 cm -1 band have been observed. Several thousand lines were assigned and these molecular constants were determined. The S 1 state is assigned to be the 1 A 1 (   *) state. The intensity arises from the vibronic coupling with the S 2 1 B 2 state. The Zeeman broadenings of the rotational lines were also observed, and the J, K-dependence were studied. As a result, the observed Zeeman effects could be explained to be originating from the magnetic moment of the S 1 1 A 1 state induced by mixing with S 2 1 B 2 state by J-L coupling, which suggests that rotationally resolved levels are not mixed with a triplet state largely. Summary Thank you for your attention !

27. band +443 cm -1 band A type ΔK a = 0, ±2, ・・・ ΔK c = ±1, ±3, ・・・ B type ΔK a = ±1,±3, ・・・ ΔK c = ±1, ±3, ・・・ C type ΔK a = ±1, ±3, ・・・ ΔK c = 0, ±2, ・・・ J c KcKc a b KaKa ΔJ = － 1, 0, 1 Calculated spectrum of 0 0 0 band

28. S 1 ←S 0 and S 2 ←S 0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm -1 ) S 1 ←S 0 S 2 ←S 0

29. Ultrahigh-resolution spectrum of 0 0 0 + 443 cm -1 band (P lines)

30. Doppler-free absorption spectoroscopy of iodine molecule Chopper PBS: Polarization Beam splitter I 2 Cell PBS Laser Photo -diode Photo -diode CW single-mode dye laser Single mode UV laser beam Doubling cavity