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Millimeter-wave Spectroscopy of the Tunneling-rotation Transitions of the D2CCD radical
M. Ohtsuki, M. Hayashi, K. Harada, K. Tanaka Department of Chemistry, Faculty of Sciences, Kyushu University
International Symposium on Molecular Spectroscopy 63rd –Meeting
The Ohio State University
Introduction
C
C
H
H H
C
CH H
Hα
H2CCH
DE0 = 16 .271 GHz
h = 1580 cm-1
J. Chem. Phys. 120, 3604 (2004)
Previous Work
b
H2CCDDE0 = 1 .186 GHz h = 1520 cm-1
D DD2CCDDE0 = ? h = ?
Present Work
DDDD
DE
0 h
DE0:Tunneling splitting h:Potential Barrier height
0+
0-
h < 1800 cm-1
000
101
202
303
211
212
110111
000
101
202
303
211
212
110111
Ka = 0 Ka = 1 Ka = 0Ka = 1
0+
0-N KaKc
a-type transition E. Kim, et al., J.C.P 116, 10713(2002)
DE0
C C
Db
Db
Daa
bIntroduction-Pure rotatonal Transition- ma = -0.1611 D
para paraortho ortho
b-type transition
R(0)
Q(1)R(1)
DE0
C C
Db
Db
Daa
b
000
101
202
303
211
212
110111
000
101
202
303
211212
110111
Ka = 0 Ka = 1 Ka = 0 Ka = 10+ 0-
Introduction-Tunneling-rotation Transition-
mb = -0.5863 D
para paraortho ortho
UV laser193 nm
Sample(Ar : 7 atm + H2: 3 atm)
+D2CCDCl : 0.2 atm
C CD
D
D
Cl
PhotolysisArF
Experimental setup
Trot=20 KC C
D
D
D
D
D D
C C
Millimeter-wave100 ~ 200 GHz
White-type multi-reflection cell (10 round trips)
Obs.
143.5 143.55143.45Frequency(MHz)
Observed Tunneling-rotation Spectra R(0)(0-←0+)
J :0.5 ←0.5 J :1.5 ←0.5Para:Ib=1
Calc.
N
S
F
F1J
Ib Ia
N : Rotation
S : Electron spin
I : Nuclear spin
Coupling of Angular Momenta
(0-)111-(0+)000
Ia= 1C
DC
D
D
S = 0.5
I b= 0,1,2
SIb Ia
Para : Ib=1 Ortho : Ib=0,2
Ortho:I b = 0,2
Observed Tunneling-rotation Spectra R(0)(0+←0-)
Obs.
J :0.5 ←0.5 J :1.5 ←0.5
142.00141.90 (GHz) 141.95
Calc. Ib = 2
Calc. Ib = 0
Frequency (GHz)
Q(1)
R(0)R(1)
Q(2)
120100 160 180
2DE0
140 GHz
(0+←0-)(0-←0+)
1.54GHz
140
Q(3)
Observed Tunneling-rotation Spectra 0-0+
DE
0
6:3
6:3
ortho
ortho
200
para
para
Constants (MHz) (average) FTMW (MHz) (average)
DE0 771.858 (24) -
A 122 560.835 (50) -
B 24 264.477 (38) (B + C)/2 = 22 220.523 32(25)C 20 175.989 (38)
eaa 120.666 (24) -
(ebb+ecc)/2 -24.11 (33) -24.095 1(19)
aF (a) 5.872 (11) 5.874 5(27)
Taa(a) 4.130 (14) 4.123 5(42)
Tbb(a) 0.97 (11) -
aF (b) 21.617 (32) 21.608 7(111)
Taa(b) 1.302 9 (80) 1.293 5(23)
Tbb(b) - 0.274 (56) -
d aF (b) 8.5 (13) -
s = 160.8kHzData:93 ( MMW(61) + FTMW(32))
Molecular Constants
Off-diagonal Fermi interaction constant
average : (0+ + 0-) / 2
Potential Barrier Height
C
C
D
D D
C
CD D
D
qmin = 43.4°
DE0 (MHz) h (cm-1)
D2CCD 771.858 (24) 1549
H2CCD 1 186.820 (21) 1520
H2CCH 16 271.842 9(59) 1580
V(q) = -V2q 2 + V4q 4
h =V2
2
4V4*qmin is fixed (CCSD(T)/TZ2P) (Chem. Phys.206, 43 (1996))DE
0 h
q
0+
0-
qmin
Ortho-Para Interaction
000
101
110
111
000
101
110
111
Ka = 0 Ka = 1 Ka = 0Ka = 10+ 0-
para ortho para ortho
R(0)Tunneling-rotation Transitions (DIb = 0)
Ortho-Para Interaction (DIb = 1)
Ortho (Ib = 0, 2)Para ( Ib = 1)
DE0= 771MHz
dn = 0.094 MHz
dn = -0.094 MHz
++
+
+
-
-
-
-
12 daF S DIbHF
( )b =
ortho-para interaction
aF( )b = (aF
( 1)b + aF( 2)b )/2
daF( )b = aF
( 1)b - aF( 2)b
DIb = I 1b - I 2b
(MHz) D2CCD H2CCD
daF( ) b 8.5 (13) 67.14 (67)
DE0 771.858 (24) 1 186.820 (21)
dn (interaction) 0.094 0.94
a2(mixing ratio) 0.012 % 0.080 %
Ib = I 1b + I 2b
Ortho-Para Interaction (DIb = 1)
dn
dn
0+ (111)
0- (111)
HF(b) = aF
( 1b ) S I 1b + aF( 2b ) S I 2b
= aF(b) S Ib + (daF
(b)S DIb)/2
○ Tunneling-rotation Transition of D2CCD radical was observed and assigned.
○ Tunneling splitting (DE0) was determined to be 771.858 (24) MHz.
○ Potential barrier height(h) was estimated to be 1549 cm-1 .
Conclusions
○ Off-diagonal Fermi interaction term,daF( ) b ,
was determined to be 8.5 (13) MHz at D2CCD.
Thank you for your attention!!