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Ultrahigh-resolution Laser Spectroscopy and The Zeeman Effect of Naphthalene S1←S0 Transition c (z) Kazuto Yoshida, Shunji Kasahara Kobe University, Japan b (y) a (x) Masaaki Baba Kyoto University, Japan Introduction PAHs (Polycyclic Aromatic Hydrocarbons) benzene naphthalene anthracene TG10 TG11 Ultrahigh-resolution laser spectroscopy Molecular Constants Linewidth Energy Shift Zeeman Effect Molecular Structure Excited-State Dynamics Excited-state dynamics S2 Internal Conversion Intramolecular Vibrational Redistribution IC InterSystem Crossing IVR ISC Naphthalene ΦF=0.4 [ F. M. Behlen, S. A. Rice, J. Chem. Phys. 75, 5672 (1981) ] S0 phosphorescence fluorescence absorption S1 T1 Electronic states : Molecular orbitals ψ36 b3g LUMO ψ36 b3g LUMO ψ35 b2g ψ35 b2g B3u B2u HOMO HOMO ψ34 au ψ34 au ψ33 b1u ψ33 b1u Electronic state Fluorescence excitation spectrum in a supersonic jet HOMO-1→LUMO HOMO→ LUMO+1 1B 3u 1B 2u S31B3u 1L a S21B2u 1L b S11B3u HOMO→LUMO S01Ag S1←S0 weak [ S. M. Beck et al., J. Chem. Phys. 73, 2019 (1980) ] S1←S0 HOMO-1→LUMO HOMO→ LUMO+1 1B S2←S0 TG11 S31B3u 3u 1L b 1B 2u 1L a S21B3u S11B2u HOMO→LUMO S01Ag S2←S0 weak (NOT FOUND) RELATIVE FREQUENCY (CM-1) High-resolution spectrum S1 ←S0 transition ag vibration b1g vibration 2122 1432 1380 1390 2410 2570 000 910 1422 435 Resolution : 0.2 cm-1 Wavenumber / cm-1 Sensitized phosphorescence excitation spectrum 1390 Fluorescence excitation spectrum 1380 Sensitized phosphorescence excitation spectrum [T. Suzuki et al., Chem. Phys. Lett. 127, 292(1986)] Experimental setup I2 stabilized Etalon Marker Single-mode laser (accuracy ：0.0001 cm-1) Ring Dye Laser Nd : YVO4 Laser Millennia Xs Ref: I2 hyperfine Calibration of absolute wavenumber Doubling cavity CR699-29 dye:R6G Wavetrain Molecular Beam linewidth ：2 MHz A B Magnet Pulse nozzle Ar + sample 100 ℃ Photon Filter PM A: skimmer φ2 mm B: slit width 1.5 mm UV Counter Computer Observed spectra ultrahigh-resolution spectrum of naphthalene accuracy : 0.0002 cm-1 600 MHz 33396.7765 cm-1 etalon marks Doppler-free saturation spectrum of I2 Wavenumber / cm-1 Ultrahigh-resolution spectra 000+1380 cm-1 band rP pP band origin rR pR b-type 000+1390 cm-1 band qP qQ qR a-type Wavenumber / cm-1 Ultrahigh-resolution spectrum of 000+1380 cm-1 band p PKa J Ka r PKa J Ka Wavenumber / cm-1 Molecular constants state S01Ag vibration ν=0 ν13=1 ν4=1 A / cm-1 0.10405207(16) 0.10138682(63) 0.10133157(34) B 0.041126892(27) 0.04048804(21) 0.04048296(26) C 0.0294838072(80) 0.02896823(11) 0.02892373(23) ΔK 1.87(32)×10-9 6.85(30)×10-8 -1.93(96)×10-9 ΔJK 1.18(22)×10-9 -1.76(10)×10-8 1.5(10)×10-9 ΔJ 5.80 (21)×10-10 5.8(11)×10-10 4.1(18)×10-10 δK 1.37(17)×10-9 7.6(12)×10-9 -6.5(22)×10-9 δJ 1.59(10)×10-10 -4.73(67)×10-10 -1.6(13)×10-10 Δ ×1046/ kgm2 -0.2419 -0.01157 0.000088 T0 / cm-1 - 33399.025060(24) 33408.227658(27) excess energy /cm-1 - 1380.428 1389.631 band type - b a std. dev - 0.00041 0.00039 2030 1756 assigned lines S11B3u Ultrahigh-resolution spectra 000+1380 cm-1 band 000+1390 cm-1 band band origin b-type a-type Wavenumber / cm-1 Comparison between observed and calculated spectrum Ka p PKa J 000+1380 cm-1 band Ka r obs. calc. Wavenumber / cm-1 PKa J Ultrahigh-resolution spectra 000+1380 cm-1 band 000+1390 cm-1 band band origin b-type a-type Wavenumber / cm-1 Comparison between observed and calculated spectrum q QKa J 000+1390 cm-1 band obs. calc. Wavenumber / cm-1 Energy shifts of 000+1390 cm-1 band ΔE / cm-1 q PKa J Ka=0 Ka=1 Ka=2 Upper J ΔE=Eobs. - Ecalc. Eobs. : observed transition energy Ecalc. : calculated transition energy The Zeeman Effect High-resolution spectrum S1 ←S0 transition 1432 2122 2410 2570 000 910 1422 1380 1390 435 We observed the Zeeman effect for rotationally resolved spectra Wavenumber / cm-1 Zeeman splitting of 000+435 cm-1 band p PK J High Ka low Ka c (z) b (y) m a (x) a H=0 T magnetic moment H=0.50 T Wavenumber / cm-1 J-dependence of Zeeman splitting 000+435 cm-1 band 000+1422 cm-1 band Kc= J (Ka= 0) ZS / cm-1 ZS / H=0.25 T H=0.50 T 0.002 0.001 0 0 0 10 20 H=0.46 T H=0.90 T 0.002 0.001 30 ZS J 40 50 J Kc= J (Ka= 0) cm-1 0 10 20 30 ZS J 40 50 J J-L coupling (electronic Coriolis interaction) JK-dependence can be well explained by J-L coupling ZS J , ZS Kc2 Magnetic moment in S11B3u state comes from J-L coupling between S11B3u and S21B2u states. The magnitude of Zeeman Splitting (ZS) is S21B2u -2 Jz Lz 2 8CK c ZS J 1 S11B3u 1 1 S2 B2u Lz S1 B3u ES2 ES1 2 B H （comparison between observed and calculated ZS） ZS of rP0(28) line (J=28, Kc=28) in 000+435 cm-1 band Observed ZS 0.0010 cm-1 Calculated ZS 0.0011 cm-1 S2 1 B2u Lz S1 1 B3u 1.628 ES2 35806cm-1 , ES1 32018cm-1 C 0.0289cm1 H 0.50 T μB 9.27410 24 JT 1 Zeeman splitting of 000+1390 cm-1 band H=0 T q PKa J H=0.27 T Wavenumber / cm-1 Summary We observed ultrahigh-resolution spectra of 000+1380 cm-1 and 000+1390 cm-1 vibronic bands of naphthalene S1←S0 transition. Several rotational lines of these vibronic bands were assigned and the rotational constants were determined in high accuracy. We determined vibrational energy of v4, v13 in high accuracy. In 000+1390 cm-1 band , the local energy shifts were found. The Zeeman splitting was very small and was proportional to J for a given K. The magnetic moment comes from an electron angular momentum induced by the J-L coupling between S11B3u and S21B2u states. The main nonradiative process of S1 state is not intersystem crossing to the triplet state. It is presumed to be internal conversion to ground state. Rotational counter transition moment long axis band origin a-type transition moment short axis b-type transition moment out of plane c-type Wavenumber / cm-1 Zeeman interaction Matrix element of Zeeman interaction K 1 1 S B v m S B v KK 1 1 3u 0 1 3u 2 J J 1 1 2 M J K J K 1 1 1 S1 1 B3u vJKM H Z S1 1 B3u vJK M MM H S B v m S B v 1 3u 1 1 3u K K 1 2 J J 1 J J 112 1 2 J K J K 1 S 1 B v m S 1 B v K 1 1 3u 1 1 3u K 2 J J 1 Magnetic moment is along to out of plane. S1 1 B3u vJKM H z S1 1 B3u vJK M MK S1 1 B3u v mz S1 1 B3u v H J J 1 M=-J M=+J ZS The magnitude of Zeeman spliiting (ZS) is ZS S1 1 B3u vJK 2K S1 1 B3u v mz S1 1 B3u v H J 1 JK-dependence of Zeeman splitting naphthalene-d8 K-dependence ZS K 2 c J-dependence ZS J v-dependence of Zeeman splitting at Ka=0 (Kc=J), J=20, H = 0.2 T Zeeman Splitting / MHz 30 25 ZS is not v-dependence 20 15 10 5 0 0 500 1000 1500 2000 2500 3000 Excess Energy / cm-1 2 8CK c ZS J 1 1 1 S2 B2u Lz S1 B3u ES2 ES1 2 B H Zeeman Splitting of glyoxal El-sayed rule Spin-orbit Interaction a l s a (lz sz l s- l- s ) 1ππ* 1nπ* 3ππ* 3nπ* Excited states of glyoxal n ππ* S31Bu S21Ag 71 S1 1Au nπ* nπ* HSO a l ·s ππ* nπ* S01Ag n T2 3Bu Hvibronic T13Au Energy shifts ΔE ΔE=Eobs.－Ecal. Coriolis interaction; parallel: proportional to K, perpendicular: proportional to [J(J+1)－(K±1)]1/2
