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
c(z)
c
c
K
J
b
Kc
b(z)
J
Kc
a(z)
oblate symmetric top
A=B>C
near prolate asymmetric top
A>B~C
J
a
Motivation for the Measurement of Excited States
by Doppler-Free / Sub-Doppler High Resolution Spectroscopy
Rotational-resolved high-resolution spectrum in UV-VIS region
Assignments of rotational transitions
Regularity
of rotational lines
Molecular constants
in high accuracy
Anomalies
of rotational lines
 Line position (energy shift)
 Line width (broadening)
 Zeeman effect (splitting)
Molecular structure
Dynamical process
Ultrahigh-resolution UV spectroscopy in molecular beam
Accuracy 0.0001 cm-1
Absolute Wavenumber Measurement System
PD
Lock-in Amp.
I2 cell
PD
EOM
Computer
Etalon marker
  0.0001 cm-1
Single-mode Laser
Nd:YVO4 Laser; Millenia Xs
Doubling Cavity;
WavetrainSC
Ring Dye Laser; CR699-29
UV Laser  Molecular Beam
UV laser
Pulse
nozzle
(FWHM)  0.0005 cm-1
Magnet
Ar gas
Liq. N2
Trap
Sample
Skimmer
Vac. pump
Vac. pump
Slit(1 mm)
Computer
Filter
Photon Counter
Frequency Marker (each 30 MHz)
PC
PD
30MHz Oscillator
Etalon
PBS
EOM
EOM
PD
λ/4
19MHz Oscillator
I2 Cell
PD
PBS
PZT
Stabilized
Error Signal Generator
Etalon
I2 stabilized
YAG laser
Error Signal Generator
EOM
PBS
19MHz Oscillator
YAG Laser
Laser
Ultrahigh-resolution UV spectroscopy in molecular beam
Accuracy 0.0001 cm-1
Absolute Wavenumber Measurement System
PD
Lock-in Amp.
I2 cell
PD
EOM
Computer
Etalon marker
  0.0001 cm-1
Single-mode Laser
Nd:YVO4 Laser; Millenia Xs
Doubling Cavity;
WavetrainSC
Ring Dye Laser; CR699-29
UV Laser  Molecular Beam
UV laser
Pulse
nozzle
(FWHM)  0.0005 cm-1
Magnet
Ar gas
Liq. N2
Trap
Sample
Skimmer
Vac. pump
Vac. pump
Slit(1 mm)
Computer
Filter
Photon Counter
Doppler-free absorption spectrum of I2
Chopper
PBS
I2 Cell
Laser
PBS
Photo
-diode
Photo
-diode
PBS: Polarization
Beam splitter
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.
Ultrahigh-resolution UV spectroscopy in molecular beam
Accuracy 0.0001 cm-1
Absolute Wavenumber Measurement System
PD
Lock-in Amp.
I2 cell
PD
EOM
Computer
Etalon marker
  0.0001 cm-1
Single-mode Laser
Nd:YVO4 Laser; Millenia Xs
Doubling Cavity;
WavetrainSC
Ring Dye Laser; CR699-29
UV Laser  Molecular Beam
UV laser
Pulse
nozzle
(FWHM)  0.0005 cm-1
Magnet
Ar gas
Liq. N2
Trap
Sample
Skimmer
Vac. pump
Vac. pump
Slit(1 mm)
Computer
Filter
Photon Counter
Pole peace
Pulse nozzle Skimmer
Molecular Beam
Sample
Slit
A
B
Liq. N2
trap
Magnet
A
B
PM
Laser
Liq. N2
trap
Pole peace
Ultrahigh-resolution spectrum of 000+ 443 cm-1 band
Marker etalon (stabilized by I2 stabilized YAG laser)
Doppler-free absorption spectrum of I2
Rotational-resolved high-resolution spectrum of Dibenzofuran
S1←S0 spectrum of dibenzofuran in a molecular beam
(resolution : 0.2 cm-1)
dibenzofuran
Ultrahigh-resolution spectrum of 000 and 000 + 443 cm-1 band
B-type transition
A-type transition
Electronic excited states of dibenzofuran molecule
z(b)
O
Ψ47
B1
Ψ46
A2
y(a)
E (cm-1)
2nd LUMO
1A
Ψ45
B1
LUMO
Ψ44
A2
HOMO
Ψ43
B1
Ψ42
A2
1
2nd HOMO
HOMO－LUMO
1B
2
( S2 )
41000
Hvibronic
55 (b2 )  1
1A
B-type
ΔKa =±1
1
( S1 )   0
34087(+443 cm-1)
33644
A-type
ΔKa = 0
1A
1
( S0 )
0
Ultrahigh-resolution spectrum of 000 and 000 + 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
-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
⊿ = Ic - Ia - Ib
Ultrahigh-resolution spectrum of 000 and 000 + 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
0
-1
0 0 + 857 cm band
34500.0
0
34503.0
cm
-1
-1
0 0 + 1150 cm band
34792.0
0
34795.0
cm
-1
-1
0 0 + 1321 cm band
34964.0
34967.0
cm
-1
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)
(00
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
-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
⊿ = Ic - Ia - Ib
S 1 1 A1
-1
0 + 857 cm )
(00
S 1 1 A1
-1
0 + 1149 cm )
(00
S1 1A 1
-1
0 + 1321 cm )
Zeeman broadening of 000 band
(J, K) dependence of the observed Zeeman splittings
-MJ
Kc = J
（Ka = 0 ）
Kc = 0
（Ka = J ）
ZS∝Kc2
ZS∝J
c
Kc
Magnetic moment is along to c-axis.
(out of plane)
J
m
a
ZS
MJ
Zeeman interaction
c(z)
c(x)
c(y)
K
J
b
Kc
b(z)
J
Kc
J
a
a(z)
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!
Summary
Rotationally resolved ultrahigh-resolution spectra of jet-cooled dibenzofuran
(DF) for the 000 and several vibronic bands up to 000 + 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.
Thank you for your attention !
c
Calculated spectrum of 000 band
J
Kc
b
Ka a
ΔJ = －1, 0, 1
A type
0 00 band
(a) A type
+443 cm-1 band
ΔKa = 0, ±2, ・・・
ΔKc = ±1, ±3, ・・・
33641
33645
cm -1
33643
33645
cm
33643
33645
cm -1
33643
(b) B type
B type
band
ΔKa = ±1,±3, ・・・
ΔKc = ±1, ±3, ・・・33641
-1
(c) C type
C type
ΔKa = ±1, ±3,・・・
ΔKc = 0, ±2,・・・
33641
S1←S0 and S2←S0 spectrum of dibenzofuran in a molecular beam
(resolution : 0.2 cm-1)
S2←S0
S1←S0
Ultrahigh-resolution spectrum of 000 + 443 cm-1 band (P lines)
CW single-mode dye laser
Doppler-free absorption spectoroscopy
of iodine molecule
Chopper
PBS
Doubling cavity
I2 Cell
Laser
PBS
Photo
-diode
Single mode
UV laser beam
Photo
-diode
PBS: Polarization
Beam splitter