High-resolution Laser Spectroscopy ISMS, Univ. of Illinois, June 2015 High-resolution Laser Spectroscopy of the S1←S0 Transition of Cl-naphthalenes Shunji Kasahara, Ryo Yamamoto, and Kenichiro Kanzawa Molecular Photoscience Research Center, Kobe University, Japan Naphthalene 2-Cl naphthalene (2-ClN) 1-Cl naphthalene (1-ClN)

Rotationally Resolved High-Resolution Laser Spectroscopy Introduction PAHs (Polycyclic Aromatic Hydrocarbons) benzene naphthalene anthracene H. Katô, M. Baba, and S. Kasahara, Bull. Chem. Soc. Jpn. 80, 456 (2007) M. Baba et. al., J. Chem. Phys. 130, 134315 (2009) D. Y. Beak et. al., Bull. Chem. Soc. Jpn. 79(1), 75 (2006), etc. K. Yoshida et. al., J. Chem. Phys. 130, 194394 (2009), etc. Rotationally Resolved High-Resolution Laser Spectroscopy Molecular Constants 　　Molecular Structure Linewidth Energy Shift Excited-State Dynamics Zeeman Effect　　　

Molecular Constants Molecular Structure Introduction Intramolecular heavy-atom effect ? S0 IC IVR ISC absorption fluorescence phosphorescence S1 S2 T1 2-Chloronaphthalene (2-ClN) 1-Chloronaphthalene (1-ClN) Molecular Constants 　　Molecular Structure Linewidth Energy Shift Excited-State Dynamics Zeeman Effect　　　

Experimental set up

Observed high-resolution spectrum Marker Etalon 16007.92763 cm-1 Doppler-free Saturation Spectrum of I2 32015.9429 cm-1 32016.0368 cm-1 32015.8435 cm-1 Sub-Doppler Fluorescence Excitation Spectrum of 2-ClN

2-Cl naphthalene (2-ClN)

Low-resolution spectrum （Vibronic bands） Dispersed Fluorescence Spectrum LIF spectrum (a) (a) (b) (c) (d) (b) (c) (d) Jacobson et al., J. Chem. Phys. 87, 269 (1987)．

High-resolution fluorescence excitation spectrum of 0-0 band of 2-ClN S1←S0 transition band origin 31419.04 cm-1 Calculated spectrum (35Cl only, a-type 18 %, b-type 82 %, Tr = 20 K, line width 15 MHz) Observed spectrum

Molecular constants of 2-35Cl naphthalene S0 (ref ) S1 (ref) υ =0 A/ cm-1 0.09114064(37) 0.08861887(36) 0.091127579(3) 0.08860664(1) B 0.01940348(24) 0.01932011(24) 0.019402605(1) 0.019319070(13) C 0.01600019(19) 0.01586561(20) 0.015999463(1) 0.01586502(2) ∆J 2.25(86) ×10-10 　2.29(86)×10-10 1.668(17)×10-10 ∆K 2.356(76)×10-9 　2.132(67)×10-8 9.23(27)×10-9 a-type 18% ∆JK 3.34(45)×10-9 　3.16(45)×10-9 1.33(30)×10-10 b-type 82% δJ 2.62(41)×10-10 　2.80(42)×10-10 3.502(67)×10-11 δK -1.37(44)×10-8 -1.43(44)×10-8　 6.7(10)×10-10 origin/cm-1 31419.0905(2) 31419.24(1) Std.dev. 0.00021 fitted lines 4583 assigned lines 4725 822 a b (ref) D. F. Plusquellic, et al. J. Chem. Phys, 115, 225 (2001)

High-resolution fluorescence excitation spectrum of 0-0 band of 2-ClN S1←S0 transition band origin 31419.04 cm-1 Calculated spectrum (35Cl only, a-type 18 %, b-type 82 %, Tr = 20 K, line width 15 MHz) Observed spectrum

High-resolution fluorescence excitation spectrum of 0-0 band of 2-ClN S1←S0 transition pPKa (J) rPKa(J) + : + : ∆Kｃ = +1 - : ∆ Kｃ= -1

Zeeman effect for the 0-0 band of 2-ClN S1←S0 transition (with magnet) H = 0 T H = 1 T rP0 (28) rP0 (27) rP0 (26) pP5 (8) pP5 (7) pP5 (9) rP0 (29)

Zeeman splittings of the 0-0 band of 2-ClN S1←S0 transition J-L coupling (electronic Coriolis interaction) 0.5 T Ka = 0 (J =Kｃ) S2 （000+435 cm-1 band） J-L coupling term -2JzLz S1 ZS : Zeeman splitting C : naphthalene : C = 0.0289 cm-1 2-Cl naphthalene : C = 0.0159 cm-1 Lz : Angular momentum along with z-axis μB : Bohr magneton J Kc a(x) b(y) c(z) For the 2-ClN, (i) the order of magnitude of Zeeman Splitting is small. 　　　　 (ii) the J- and K-dependences are found. 　ZS ∝ (Kc)2, ZS ∝ J 　　　These results are almost the same as naphthalene. Foe benzene and naphthalene,　Bull. Chem. Soc. Jpn. 80, 456 (2007) ，etc.

Low-resolution spectrum （Vibronic bands） Dispersed Fluorescence Spectrum LIF spectrum (a) (a) (b) (c) (d) (b) 0 – 0 band τ = 31ns → Γ = 5.1 MHz (c) 000 + 1042 cm-1band τ = 11 ns → Γ = 14 MHz (d) Jacobson et al., J. Chem. Phys. 87, 269 (1987)．

High-resolution fluorescence excitation spectrum of 000+1042 cm-1 band of 2-ClN S1←S0 transition band origin: 32460.9296 (1) cm-1 Trot = 30 K a-type:b-type = 1:3 Linewidth (FWHM) 50 MHz band origin Calc. Obs.

Molecular constants of 2-35Cl naphthalene S0 (ref ) S1 (ref) υ =0 1042 cm-1 band A/ cm-1 0.09114064(37) 0.08861887(36) 0.8856981(26) 0.091127579(3) 0.08860664(1) B 0.01940348(24) 0.01932011(24) 0.019303195(85) 0.019402605(1) 0.019319070(13) C 0.01600019(19) 0.01586561(20) 0.015852213(36) 0.015999463(1) 0.01586502(2) ∆J 2.25(86) ×10-10 　2.29(86)×10-10 1.668(17)×10-10 ∆K 2.356(76)×10-9 　2.132(67)×10-8 9.23(27)×10-9 a-type 18% ∆JK 3.34(45)×10-9 　3.16(45)×10-9 1.33(30)×10-10 b-type 82% δJ 2.62(41)×10-10 　2.80(42)×10-10 3.502(67)×10-11 δK -1.37(44)×10-8 -1.43(44)×10-8　 6.7(10)×10-10 origin/cm-1 31419.0905(2) 32460.9301(2) 31419.24(1) Std.dev. 0.00021 0.00077 fitted lines 4583 1596 assigned lines 4725 1651 822 a b (ref) D. F. Plusquellic, et al. J. Chem. Phys, 115, 225 (2001)

High-resolution fluorescence excitation spectrum of 000+1042 cm-1 band of 2-ClN S1←S0 transition band origin: 32460.9296 (1) cm-1 Trot = 30 K a-type:b-type = 1:3 Linewidth (FWHM) 50 MHz band origin Calc. Obs.

High-resolution fluorescence excitation spectrum of 000+1042 cm-1 band of 2-ClN S1←S0 transition Calc. Obs.

Energy shifts in the 000+1042 cm-1 band of 2-ClN S1←S0 transition

High-resolution spectrum of vibronic band of 2-ClN S1←S0 transition ×1 Excess Energy 476 1042 1396 Lifetime (ns) 31 23 11 8 Natural Line width (MHz) 5.1　 6.9　 14 20 0 – 0 ×3.5 000+476 cm-1 ×3.5 000+1042 cm-1 ×3.5 000+1396 cm-1

1-Cl naphthalene (2-ClN)

High-resolution fluorescence excitation spectrum of 0-0 band of 1-Cl naphthalene (1-ClN) S1←S0 transition S0: A = 0.050572(30), B = 0.030095(84), C = 0.0191249(35)　[cm-1] S1: A = 0.049720(31), B = 0.029615(84), C = 0.0188965(35) [cm-1] band origin 31574.7730(3) cm-1 Trot = 60 K a-type:b-type = 1:2 Linewidth (FWHM) 120 MHz band origin Calc. Obs. Wavenumber / cm-1

High-resolution fluorescence excitation spectrum of 0-0 band of 1-Cl naphthalene (1-ClN) S1←S0 transition Calc. Obs.

Zeeman effect for the 0-0 band of 1-ClN S1←S0 transition (with magnet) Zeeman splittings are not found because (1) Zeeman splittings are small. (2) the rotational lines are overlapped even if there are J, K-dependence. What is the background? H = 1.2 T H = 0 T Wavenumber / cm-1

Summary We have observed high-resolution fluorescence excitation spectra and their Zeeman effect by crossing a UV laser perpendicular to a molecular beam. 2-ClN 1-ClN Measurement of the 0-0 band ・Rotationally resolved spectra have been observed and assigned. (Typical linewidth was 15 MHz) ・Rotational line has not been resolved. (Typical linewidth was 120 MHz) ・Molecular constants were estimated from simulation and partial assignment of the observed spectrum. Under the external magnetic field up to 1.2 T ・Zeeman effect has been observed. ・Zeeman splittings are small. ・J, K-dependence were found. ・Zeeman effect has not been observed. *There is strong background signal. 　Measurement of the vibronic bands ・Rotationally resolved spectra have been observed and assigned. ・Energy shifts were found. ・Not yet.

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Comparison between 1-ClN and 2-ClN for the 0-0 band of S1←S0 transition (1) 2-ClN 0-0 band: τ = 31 ns *, Γ = 5.1 MHz band origin 31416　　　 31417　　　　31418　 　 31419 　 　　31420　 　　31421　　 　31422 1-ClN 0-0 band: τ = 3.4 ns*, Γ = 47 MHz 31571　　 　31572　　　 31573　 　31574　 　　31575　　　　31576　 　　31577 *Jacobson et al., J. Chem. Phys. 87, 269 (1987). Wavenumber / cm-1

Comparison between 1-ClN and 2-ClN for the 0-0 band of S1←S0 transition (2) 2-ClN 0-0 band: τ = 31 ns *, Γ = 5.1 MHz 　31417.7　　　　 　 　　　 31417.8　　　　 31417.9 　　 　　　 31418.0 1-ClN 0-0 band: τ = 3.4 ns*, Γ = 47 MHz 31573.4　　　　 　　　　31573.5　 　　　 　　31573.6　　　　 　　　31573.7 *Jacobson et al., J. Chem. Phys. 87, 269 (1987). Wavenumber / cm-1