ULTRAHIGH-RESOLUTION SPECTROSCOPY OF

DIBENZOFURAN S1←S0 TRANSITION

SHUNJI KASAHARA1, Michiru Yamawaki1, and Masaaki Baba2

1) Molecular Photoscience Research Center, Kobe University, Japan

2) Graduate School of Science, Kyoto University, Japan

JK

c(z)

J

Kc

c

a

oblate symmetric top

A=B>C

b(z)

near prolate asymmetric top

A>B~C

J

Kc

a(z)

b

c

Motivation for the Measurement of Excited States by Doppler-Free / Sub-Doppler High Resolution Spectroscopy

Rotational-resolved high-resolution spectrum in UV-VIS region

Regularityof 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 structureDynamical process

Nd:YVO4 Laser; Millenia Xs

MagnetAr gas

Pulse nozzle

Sample

Filter

UV laser

Etalon marker

PD

I2 cell

Lock-in Amp.

EOMPD

Skimmer

Slit(1 mm)

Vac. pump Vac. pumpPM

Ring Dye Laser; CR699-29

UV Laser Molecular Beam

Single-mode Laser

Absolute Wavenumber Measurement System

Doubling Cavity; WavetrainSC

Computer

Computer

Photon Counter

Accuracy 0.0001 cm-1

0.0001 cm-1

Ultrahigh-resolution UV spectroscopy in molecular beam

Liq. N2 Trap

(FWHM) 0.0005 cm-1

EtalonPBS

PD λ/4 PZT

YAG Laser

Error Signal Generator

19MHz Oscillator

EOM

PBS

Error Signal Generator19MHz Oscillator

I2 stabilized YAG laserI2 Cell PD

PBS

PC

StabilizedEtalon

EOM

PD

LaserEOM

30MHz Oscillator

Frequency Marker (each 30 MHz)

Nd:YVO4 Laser; Millenia Xs

MagnetAr gas

Pulse nozzle

Sample

Filter

UV laser

Etalon marker

PD

I2 cell

Lock-in Amp.

EOMPD

Skimmer

Slit(1 mm)

Vac. pump Vac. pumpPM

Ring Dye Laser; CR699-29

UV Laser Molecular Beam

Single-mode Laser

Absolute Wavenumber Measurement System

Doubling Cavity; WavetrainSC

Computer

Computer

Photon Counter

Accuracy 0.0001 cm-1

0.0001 cm-1

Ultrahigh-resolution UV spectroscopy in molecular beam

Liq. N2 Trap

(FWHM) 0.0005 cm-1

Chopper

PBS: Polarization Beam splitter

I2 Cell

PBS

PBSLaser

Photo-diode

Photo-diode

Doppler-free absorption spectrum of I2

Absolute wavenumber of each I2 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.

Nd:YVO4 Laser; Millenia Xs

MagnetAr gas

Pulse nozzle

Sample

Filter

UV laser

Etalon marker

PD

I2 cell

Lock-in Amp.

EOMPD

Skimmer

Slit(1 mm)

Vac. pump Vac. pumpPM

Ring Dye Laser; CR699-29

UV Laser Molecular Beam

Single-mode Laser

Absolute Wavenumber Measurement System

Doubling Cavity; WavetrainSC

Computer

Computer

Photon Counter

Accuracy 0.0001 cm-1

0.0001 cm-1

Ultrahigh-resolution UV spectroscopy in molecular beam

Liq. N2 Trap

(FWHM) 0.0005 cm-1

PM

Magnet

Laser

A

A

B

B

Skimmer

Pulse nozzle

Sample

Pole peace

Pole peace

Slit

Molecular Beam

Liq. N2 trap

Liq. N2 trap

Marker etalon (stabilized by I2 stabilized YAG laser)

Doppler-free absorption spectrum of I2

Rotational-resolved high-resolution spectrum of Dibenzofuran

Ultrahigh-resolution spectrum of 000+ 443 cm-1 band

S1←S0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm-1)

dibenzofuran

Ultrahigh-resolution spectrum of 000 and 00

0 + 443 cm-1 band

B-type transition

A-type transition

Ψ47B1

Ψ46

Ψ45

Ψ44

A2

B1

A2

Ψ43 B1

Ψ42 A2

HOMO

LUMO

2nd LUMO

2nd HOMO

34087(+443 cm-1)

0

1A1

1A1 ( S0 )

1B2 ( S2 )

1A1 ( S1 )

Hvibronic

A-typeΔKa = 0

B-typeΔKa =±1

1)( 255 b

E (cm-1)

0

33644

41000HOMO－ LUMO

Electronic excited states of dibenzofuran molecule

y(a)

z(b)

O

Ultrahigh-resolution spectrum of 000 and 00

0 + 443 cm-1 band

Ultrahigh-resolution spectrum of 000 band (P lines)

Obtained Molecular Constants of S1 and S0 States of dibenzofuran

S0 1A1 (v=0) S1

1A1 (v=0)

A (cm-1) 0.0759913(10) 0.07527912(81)

B 0.02005071(65) 0.01982969(29)

C 0.01586638(57) 0.01569587(17)

DK (×10-8) 3.67(22) 3.33(19)

DJK (×10-8) -3.43(15) -3.328(70)

DJ (×10-9) 5.20(27) 5.374(88)

δK (×10-7) 3.26(11) 3.106(21)

δJ (×10-9) 1.79(13) 2.102(49)

κ -0.86091 -0.86124

Ia (×10-46 kg m2) 36.83678 37.18528

Ib 139.60976 141.16584

Ic 176.42807 178.34467

⊿ = Ic- Ia- Ib -0.01847 -0.00644

T0 (cm-1) - 33644.347663(66)

standard deviation - 0.00059

fitted lines - 4835 lines

assigned lines - 5032 lines

band type - B type

Ultrahigh-resolution spectrum of 000 and 00

0 + 443 cm-1 band

Ultrahigh-resolution spectrum of 000 + 443 cm-1 band (Q lines)

S1←S0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm-1)

dibenzofuran

Ultrahigh-resolution spectrum of higher vibrational band

34964.0 34967.0 cm-1

00 + 1321 cm-1 band0

34792.0 34795.0 cm-1

00 + 1150 cm-1 band0

00 + 857 cm-1 band

34500.0 34503.0 cm-1

0

Obtained Molecular Constants of S1 and S0 States of dibenzofuran

S0 1A1 (v=0) S1

1A1 (v=0)S1

1A1 (b2:v55=1)

(000 + 443 cm-1)

S1 1A1

(000 + 857 cm-1)

S1 1A1

(000 + 1149 cm-1)

S1 1A1

(000 + 1321 cm-1)

A (cm-1) 0.0759913(10) 0.07527912(81) 0.07509478(55) 0.07520210(95) 0.0750354(15) 0.0745546(53)

B 0.02005071(65) 0.01982969(29) 0.01985611(25) 0.01983592(28) 0.0198581(50) 0.01987367(51)

C 0.01586638(57) 0.01569587(17) 0.01571066(20) 0.01570413(15) 0.01570651(27) 0.01571172(26)

DK (×10-8) 3.67(22) 3.33(19) 3.24(12) 3.12(20) - 2.81(41)

DJK (×10-8) -3.43(15) -3.328(70) -3.099(58) -3.224(71) - -1.099(78)

DJ (×10-9) 5.20(27) 5.374(88) 4.826(82) 5.763(61) - 5.83(21)

δK (×10-7) 3.26(11) 3.106(21) 2.976(27) 3.474(16) - 2.830(52)

δJ (×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

Ia (×10-46 kg m2) 36.83678 37.18528 37.27656 37.22336 37.30606 37.54664

Ib 139.60976 141.16584 141.97801 141.12150 140.96388 140.85344

Ic 176.42807 178.34467 178.17678 178.25087 178.22386 178.14676

⊿ = Ic- Ia- Ib -0.01847 -0.00644 -0.07778 -0.09399 -0.04608 -0.23532

T0 (cm-1) - 33644.347663(66) 34087.498758(52) 34501.877194 (82) 34794.46442(13) 34965.918929(98)

standard deviation

- 0.00059 0.00034 0.00054 0.00068 0.0010

fitted lines - 4835 lines 2904 lines 2449 lines 135 lines 999 lines

assigned lines - 5032 lines 3047 lines 2529 lines 140 lines 1048 lines

band type - B type A type A type A type A type

Zeeman broadening of 000 band

ZS∝Kc2 ZS∝J

Kc = 0（ Ka = J

）

Kc = J（ Ka = 0

）

J

c

Kc

a

m

Magnetic moment is along to c-axis. (out of plane)

(J, K) dependence of the observed Zeeman splittings

ZS-MJ MJ

J

K

c(z)

J

Kc

a

b(z)J

Kc

a(z)

b

Zeeman interaction

c(y) 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 (∝ Kc)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!

Rotationally resolved ultrahigh-resolution spectra of jet-cooled dibenzofuran

(DF) for the 000 and several vibronic bands up to 00

0 + 1335 cm-1 band have been

observed. Several thousand lines were assigned and these molecular constants

were determined.

The S1 state is assigned to be the 1A1 ( *) state. The intensity arises from the

vibronic coupling with the S2 1B2 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 S1 1A1 state

induced by mixing with S2 1B2 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 !

33641 33643 33645

33795.8507.14850D-02 1.59420D-02 1.30350D-026.94200D-02 1.58370D-02 1.30350D-02FWHM=0.007cm-1(210MHz)J<100, K<50

(b) B type

(c) C type

0 band

33641 33643 33645

cm-1

-1

-1

cm

cm

(a) A type

00

33641 33643 33645

band

+443 cm-1 bandA type　 ΔKa = 0, ±2, ・・・

　 ΔKc = ±1, ±3, ・・・

B type　 ΔKa = ±1,±3, ・・・

　 ΔKc = ±1, ±3, ・・・C type　 ΔKa = ±1, ±3, ・・・

　 ΔKc = 0, ±2, ・・・

J

c

Kc

a

b

Ka

ΔJ = － 1, 0, 1

Calculated spectrum of 000 band

S1←S0 and S2←S0 spectrum of dibenzofuran in a molecular beam (resolution : 0.2 cm-1)

S1←S0

S2←S0

Ultrahigh-resolution spectrum of 000 + 443 cm-1 band (P lines)

Doppler-free absorption spectoroscopy

of iodine molecule

Chopper

PBS: Polarization Beam splitter

I2 Cell

PBS

PBSLaser

Photo-diode

Photo-diode

CW single-mode dye laser

Single mode UV laser beam

Doubling cavity