1. Ultrahigh-resolution Laser Spectroscopy of the S1← S0 Transition of Anthracene
Masaaki Baba
(Kyoto University)
Yosuke Semba
Kazuto Yoshida
Shunji Kasahara
(Kobe University)

2. Excited-state Dynamics of PAHs
τF ns ns ns
dissociation
ISC T1
fluo. S0
phos. IC S1
abs.
IVR S2

3. Rotationally Resolved Ultrahigh-resolution Spectroscopy
Structure
♣Molecular structure by rotational constants
♦Electronic structure by selection rules
Dynamics
♥Internal conversion (IC), predissociation
by linewidth
♠Intramolecular vibrational redistribution
(IVR) by energy shifts
♪Intersystem crossing by Zeeman splitting

4. Molecular Orbitals of Anthracene
ψ47
HOMO
ψ48
LUMO
ψ49
ψ46
S1 1B2u
ψ48
LUMO
ψ49
ψ46
S2 1B3u
ψ47
HOMO Au
B1u
B3g
B2g

5. S1 and S2 state of PAHs B3u CI B3u 1Lb S2 B2u 1La S1 S0 HOMO→LUMO +1

6. S1 and S2 state of PAHs S0
1La S1 S2
1Lb
1La
1Lb
1Lb
1Lb S2
1La
1La S1

7. Excitation and Dispersed Spectra in a Supersonic Jet

8. Excited-state Dynamics in Anthracene
S. Okajima, B. E. Forch, and E. C. Lim, J. Phys. Chem. 87, 4571 (1983)
☆ Fluorescence lifetime of deuterated anthracene
h10 18 ns, d1 9 ns, d8 22 ns, d9 17 ns, d10 4 ns
(Inverse deuterium effect on ISC)
W. R. Lambert, P. M. Felker, and A. H. Zewail, J. Chem. Phys. 81, 2209 (1984)
☆ Fluorescence lifetime (nonradiative decay rate)
Dispersed fluorescence spectrum (IVR)
M. Sonnenschein, A. Amirav, and J. Jortner, J. Phys. Chem. 87, 4571 (1983)
☆ Fluorescence quantum yield of anthracenes
h , d (T2,T3 effect on ISC)
V. Bendkowski, E.Heinecke, and A. Hese, J. Chem. Phys. 127, (2007)
☆ Rotationally resolved spectrum and the Stark effect

9. Ultrahigh-resolution UV spectroscopy in molecular beam
Doubling cavity UV
Ring Ti:S Laser PM
Photon
Counter
Magnet
ΔE < cm-1
Computer
Millenia X
CR699-29
Wavetrain
Ar +
sample
Pulse nozzle
150 ℃ A B
A: skimmer, φ2 mm
B: slit, width 2 mm
Etalon Marker
Ref:I2 absorption
Nd YVO4 Laser
Ultrahigh-resolution UV spectroscopy in molecular beam
Doubling cavity UV
Ring Dye Laser PM
Photon
Counter
Magnet
ΔE < cm-1
Computer
Millenia X
CR699-29
Wavetrain
Ar +
sample
Pulse nozzle
150 ℃ A B
A: skimmer, φ1 mm
B: slit, width 0.5 mm
Etalon Marker
Ref: I2 hyperfine
Nd YVO4 Laser

10. S1 ← S0 000 Bands of Anthracene-h10 and d10

11. Molecular Constants (cm-1)
Anthracene-h Anthracene-d10
S01Ag(v"=0) S11B1u(v'=0) S01Ag(v"=0) S11B1u(v'=0)
A (4) (4) (7) (7)
B (3) (3) (4) (4)
C (2) (2) (2) (2)
DK (×10-8) (15) (14) (27) (32)
DJK (×10-8) (93) (87) (16) (16)
DJ (×10-9) (16) (16) (32) (31)
K (×10-7) (64) (65)
J (×10-9) (78) (77) 
 (10-46 kgm2)
T (3) (3)
Fit lines 

12. Calculated molecular structure
A B C
Obs
Calc
A B C
Obs
Calc
MP2 / 6-31G(d,p)
RCIS / G

13. S1 ← S0 000 Bands of Anthracene-h10 and d10

14. Rotational dependence of Zeeman broadening

15. S B J-L coupling -2Cv Jz Lz Zeeman splittings are the largest at
(Electronic Coriolis Interaction) S 2 1 B 3u u
-2Cv Jz Lz
Lz : z-component of orbital angular momentum of electrons
Magnetic moment
<S11B2u|mz|S21B3u>
mz = - μB Lz
M = - J
M = + J Γ
Zeeman splittings are the largest at
J = Kc (Ka=0) and proportional to J.

16. Excitation and Dispersed Spectra in a Supersonic Jet

17. Summary
Rotationally resolved high-resolution spectra of the S1  S0 transition of anthracene-h10 and -d10 have been observed. The natural linewidth of anthracene-d10 is cm-1 (lifetime 4 ns), which is much larger than that of –h10.
The Zeeman splitting is very small both for anthracene-h10 and -d10. The main radiationless process in the S1 state is not ISC to the triplet state, but IC to the ground state.

18. Direction of the Transition Moment
ΔKa = 0, ±2, ・・・
ΔKc = ±1, ±3, ・・・
1B3u ← S0 1Ag
A type
1B2u ← S0 1Ag
B type
1B1u ← S0 1Ag
C type
ΔKa = ±1,±3, ・・・
ΔKc = ±1, ±3, ・・・
ΔKa = ±1,±3, ・・・
ΔKc = ±1, ±3, ・・・
ΔKa = ±1, ±3,・・・
ΔKc = 0, ±2,・・・
ΔKa = ±1, ±3,・・・
ΔKc = 0, ±2,・・・

19. S11Au(v7=1)←S01Ag Band of Glyoxal

20. Zeeman Splittings in the 2+,30 line

21. IVR in the S1 state of Anthracene
W. R. Lambert, P. M.
Felker
, and A. H.
Zewail ,
J. Chem. Phys.
81, 2209 (1984)

22. Lifetime in the S1 state of Anthracene
d10
h10
W. R. Lambert, P. M.
Felker
, and A. H.
Zewail ,
J. Chem. Phys.
81, 2209 (1984)