study of the ch 2 i + o 2 reaction with a step-scan fourier-transform infrared absorption...
DESCRIPTION
3 Experimental observation of CH 2 OO Photoionization mass spectrometry Taatjes et al, J. Am. Chem. Soc. 130, (2008) Welz et al, Science 335, 204 (2012) Huang et al., J. Phys. Chem. Lett 3, 3399 (2012) Stone et al. Phys. Chem. Chem. Phys. 15, (2013) Proposed mechanismTRANSCRIPT
Study of the CH2I + O2 Reaction with a Step-scan Fourier-transform Infrared Absorption Spectrometer:
Spectra of the Criegee Intermediate CH2OO and Dioxirane(?)
1
Yu-Hsuan Huang1 and Yuan-Pern Lee1, 2
1 Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Taiwan
2 Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan
69th International Symposium on Molecular Spectroscopy
2
Importance of CH2OOCriegee mechanism important for the removal of unsaturated hydrocarbons and for the production of OH in the atmosphere R. Criegee, Rec. Chem. Prog. 18, 111 (1957)
++
Decomposition of CH2OO
Chen et al., J. Phys. Chem. A 106, 1877 (2002)
(kcal/mol-1)
stabilizationIsomerization and decomposition
HCOOH, OH, CH3,
CO, CO2, etc
(primary ozonide)
(Criegee intermediate)
Simplest Criegee internediate:CH2OO
3
Experimental observation of CH2OOPhotoionization mass spectrometry
Taatjes et al, J. Am. Chem. Soc. 130, 11883 (2008)Welz et al, Science 335, 204 (2012)
• CH2I + O2 CH2OO + I
Huang et al., J. Phys. Chem. Lett 3, 3399 (2012)Stone et al. Phys. Chem. Chem. Phys. 15, 19119 (2013)
Proposed mechanism
CH2I + O2 → CH2IOO*CH2OO + I
CH2IOOM
0
1
0
1
0
2
0
2
0
2
1500 1400 1300 1200 1100 1000 900 800
0
2
IR In
teni
sity
/arb
. uni
tA
bsor
bacn
e /1
0-2
Wavenumber /cm-1
(f) cis-CH2IOO
(e) methylenebis(oxy)
(d) dioxirane
(c) CH2OO
(b) expt. 0-12.5s
(a) CH2I2
4
IR Identification of CH2OOComparison of observed spectrum with simulated spectrum (1 cm-1)
Su et al., Science 340, 174 (2013)
5
Experimental setup
6Absorption spectrum at 0.25 cm-1 resolution
0
2
4
6
1450 1400 1350 1300 1250 1200 950 900 850 800
0
2
4
6
A
bsor
banc
e / 1
0-
Wavenumber / cm-
0-12.5 μs
0-25 μs
1 cm-1
0.25 cm-1
CH2I2/N2/O2 (0.13/2.77/97.12)@248 nm, Pt = 94 torr
ν8
ν6ν4
ν3 ν5
Su et al., Science 340, 174 (2013)
7Spectral analysis: near prolate approximation a
b
c
κ = -1 prolateκ = +1 oblate
for CH2OO
Parallel transitions
𝐹 (𝜐 , 𝐽 ,𝐾 )=𝜈𝜐+(𝐴¿¿𝜐−~𝐵𝜐)𝐾 2+~𝐵𝜐 𝐽 ( 𝐽+1 ) ¿
~𝑩𝝊=(𝑩𝝊+𝑪𝝊)
𝟐
Perpendicular transitions
𝜈 𝐽 ,𝐾=𝜈0+ [ Δ 𝐴− Δ~𝐵 ] 𝐾2+∆~𝐵 𝐽 ( 𝐽+1 )
𝜈 𝐽 ,𝐾=𝜈0+ [ Δ 𝐴− Δ~𝐵 ] 𝐾2+(∆~𝐵 𝐽+2~𝐵′ ) ( 𝐽+1 )
ΔJ = 0, Q branch
ΔJ = 1, R branch
ΔJ = -1, P branch 𝜈 𝐽 ,𝐾=𝜈0+ [ Δ 𝐴− Δ~𝐵 ] 𝐾2+¿
,
𝜈 𝐽 ,𝐾=𝜈0+ (𝐴′ −~𝐵′)+[ Δ 𝐴− Δ~𝐵 ] 𝐾2 ± 2 (𝐴′ −~𝐵′ )𝐾Q branch
a-type
b-type & c-type
Rotational constants of vibrational ground state
M. Nakagima and Y. Endo, J. Chem. Phys. 139, 101103 (2013)
Cs
-15 -10 -5 0 5 10 15
4.0
4.1
4.2
4.3
4.4
4.5
4.6
4.7
R
spac
ing
(K2)
P
V8
y = -0.023 x+ 4.33
0
2
900 890 880 870 860 850 840 830 820 810 800
0
2
A
bsor
banc
e / 1
0-
Wavenumber / cm-
Expt. 1 cm-1
8
Spectral analysis of ν8
CH2 wagging (ν8) c-type
0
2
900 890 880 870 860 850 840 830 820 810 800
0
2
RQ6RQ
5RQ
4RQ
3PQ
5PQ
6PQ
7PQ
8
A
bsor
banc
e / 1
0-
Wavenumber / cm-
Δ𝜈= [ Δ 𝐴− Δ 𝐵 ] Δ(𝐾¿¿2)+2 (𝐴′ −𝐵′ )¿
cm-1 ground ν8
ν 847.3
A 2.59355 2.57862
B 0.41580 0.41475
C 0.35762 0.35807
0
5
0
2
Simulation
RQ6RQ
5RQ
4RQ
3PQ
5PQ
6PQ
7PQ
8
Expt. 0.25 cm-1
Expt. -0.023 2.17
simulation -0.015 2.19
0
2
4
950 940 930 920 910 900 890 880 870 8600
2
4
A
bsor
banc
e / 1
0-
Wavenumber / cm-
Expt. 1 cm-1
9
Spectral analysis of ν6
O-O stretching (ν6) a-type:b-type = 0.98:0.02
Δ𝜈=¿
9
𝜈 𝐽 ,𝐾=𝜈0+ [ Δ 𝐴− Δ 𝐵 ] 𝐾2+∆𝐵𝐽 ( 𝐽+1 )
Δ B < 0
Δ A -Δ B <0, from Q
cm-1 ground ν6
ν 909.2
A 2.59355 2.57880
B 0.41580 0.41330
C 0.35762 0.35539
Expt. 0.25 cm-1
0
2
4
0
2
4
Simulation
RQ6RQ
5RQ
4RQ
3PQ
5PQ
6PQ
7PQ
8
Expt. 0.25 cm-1
Δ𝜈=2𝐵′+2 Δ 𝐵( 𝐽+1)
0
2
4
6
0
2
4
6
1480 1460 1440 1420 1400 1320 1300 1280 1260 1240
0
1
2
3
Expt. 0.25 cm-1
Simulation
Expt. 1 cm-1
Wavenumber / cm-
A
bsor
banc
e / 1
0-
10
Simulation of ν3 and ν4
CH2 scissor/ C=O str. (ν3)a-type:b-type = 0.99:0.01
cm-1 ground ν3 ν4
ν 1434.1 1285.7
A 2.59355 2.59976 2.5954
B 0.41580 0.41504 0.4190
C 0.35762 0.35658 0.3540 C=O str./CH2 scissor (ν4)a-type:b-type=0.88:0.12
0
1
2
0
1
2
1480 1460 1440 1420 1400 1320 1300 1280 1260 1240
0
1
2
3
Expt. 0.25 cm-1
Simulation
Expt. 1 cm-1
Wavenumber / cm-
A
bsor
banc
e / 1
0-
Expt. 1 cm-1
11
Simulation of ν5
0
1
2
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0
1
2
A
bsor
banc
e / 1
0-
Wavenumber / cm-
CH2 rocking (ν5)a-type:b-type = 0.53:0.47
cm-1 ground ν5
ν 1241
A 2.59355 2.61000
B 0.41580 0.41641
C 0.35762 0.35627
?
Expt. 0.25 cm-1
0
1
2
0
1
2
Simulation
CH2I + O2 → CH2IOO*
CH2OO + I↓
0
1
0
1
0
1
1400 1300 1200 1100 1000 900 8000
1
102 torr
A
bsor
banc
e/ 1
0-2
206 torr
303 torr
wavenumber / cm-1
403 torr
12
Pt = 102 torr
Pt = 206 torr
Pt = 303 torr
CH2I2/N2/O2 + 308 nm under different PN2 1-7 μs, R = 1cm-1
Pt = 403 torr
0
5
0
20
40
substracted spectraPt= 403 torr
A
bsor
banc
e/ 1
0-3
simulation of CH2IOO
Inte
nsity
/ ar
b. u
nit
0
4
8
1340 1320 1300 1280 1260 1240 1220 1200 1180
0
4
8
Expt. 0.5 cm-1
Simulation
b
sorb
ance
/ 10
-
Wavenumber / cm-
Observed spectra of CH2IOO and simulations
CH2I2/O2/N2 (0.06/16/94)@308 nm, Pt = 300 torr
CH2OO ν4
CH2IOO ν4 = 1233.6 cm-1
CH2IOO ν5 = 1228 cm-1
13
0
1
2
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 11800
1
A
bsor
banc
e / 1
0-
Wavenumber / cm-
Expt. 1 cm-1
14
Simulation of ν5
CH2 rocking (ν5)a-type:b-type = 0.53:0.47
?Expt. 0.25 cm-1
0
1
2
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 11800
1
A
bsor
banc
e / 1
0-
Wavenumber / cm-
1213 cm-1
CH2IOO : ν4 = 1233.6 cm-1, ν5 =1228 cm-1
Simulation
ν5 of CH2OO ?
0
2
4
0
2
4
1350 1300 1250 1200 1150 950 900 850 8000
6
12
Expt.
Simulation
Wavenumber / cm-
SimulationA
bsor
banc
e / 1
0-
15
Identification of Dioxirane ?Comparison of observed spectrum with simulated spectrum (0.25 cm-1)
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0.0
1.5
3.0
Wavenumber / cm-
b
sorb
ance
/ 10
- Expt.
simulation
16
cm-1 ground ν3 ν7
ν dioxirane 1231.5 1213.2
A 0.96657 0.9715 0.9605
B 0.83578 0.8372 0.8302
C 0.49301 0.4945 0.4966 C-O sym. str. (ν3)b-type
CH2 rock (ν7)c-typeSuenram and Lovas, J. Am. Chem. Soc. 100, 5117 (1978)
Dioxirane: ν3 and ν7
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0.0
1.5
3.0
Wavenumber / cm-
b
sorb
ance
/ 10
- Expt.
simulation
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0.0
1.5
3.0
Wavenumber / cm-
b
sorb
ance
/ 10
- Expt.
simulation
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0.0
1.5
3.0
Wavenumber / cm-
b
sorb
ance
/ 10
- Expt.
simulationν5 of CH2OO : 1230.7 cm-1
17
cm-1 ground ν3 ν7
ν dioxirane 1231.5 1213.2
A 0.96657 0.9715 0.9605
B 0.83578 0.8372 0.8302
C 0.49301 0.4945 0.4966 C-O sym. str. (ν3)b-type
CH2 rock (ν7)c-type
Dioxirane: ν3 and ν7
Suenram and Lovas, J. Am. Chem. Soc. 100, 5117 (1978)
1290 1280 1270 1260 1250 1240 1230 1220 1210 1200 1190 1180
0.0
1.5
3.0
Wavenumber / cm-
b
sorb
ance
/ 10
- Expt.
simulation
18
cm-1 ground ν9
ν dioxirane 899.8
A 0.96657 0.95956
B 0.83578 0.83700
C 0.49301 0.50264C-O asym. str. (ν9)
a-type
Dioxirane: ν9
Suenram and Lovas, J. Am. Chem. Soc. 100, 5117 (1978)
950 940 930 920 910 900 890 880 870 860
0
5
Wavenumber / cm-
b
sorb
ance
/ 10
-
Expt. 0.25 cm-1
Simulation
950 940 930 920 910 900 890 880 870 860
0
5
Wavenumber / cm-
b
sorb
ance
/ 10
-
Expt. 0.25 cm-1
Simulation
0
3
1450 1400 1350 1300 1250 1200 950 900 850 8000
3
Expt. 0.25 cm-1
Sum of Simulation
Wavenumber / cm-
A
bsor
banc
e / 1
0-
1. High resolution IR spectrum of CH2OO• definative assignment of ν3, ν4, ν6 and ν8
• ν5 was misassigned• band origins of ν3, ν4, ν6 and ν8 are determined
19
Summary
CH2OO ν3 ν4 ν5 ν6 ν8
Expt. 1434.1 (15) 1285.7 (32
) 1230.7 (8) 909.2 (100) 847.3 (12
)
Theo. 1458 (31) 1302 (16
) 1220 (18) 892 (106
) 853 (30)
0
3
1450 1400 1350 1300 1250 1200 950 900 850 8000
3
Expt. 0.25 cm-1
Sum of Simulation
Wavenumber / cm-
A
bsor
banc
e / 1
0-
20
Summary2. IR absorption spectrum of CH2IOO
• overlapped bands of ν4 / ν5 and ν7 (overlapped with CH2OO)• yield increases with pressure
CH2IOO ν4 ν5 ν7
Expt. 1233.6 (27) 1228 (6) 919 (13)
p-H2 Matrix 1231.8 (53) 1225.6/1226.5 (19) 917.7 (50)
Theo. 1235 (28) 1231 (35) 901.4 (50)
0
3
1450 1400 1350 1300 1250 1200 950 900 850 8000
3
Expt. 0.25 cm-1
Sum of Simulation
Wavenumber / cm-
A
bsor
banc
e / 1
0-
21
Summary
3. Possible observation of Dioxirane
Dioxirane ν3 ν7 ν9
Expt. 1231.5 (23) 1213.2 (2) 899.8 (10)
Theo. 1238 (48) 1149 (7) 911 (26)
0
3
1450 1400 1350 1300 1250 1200 950 900 850 8000
3
Expt. 0.25 cm-1
Sum of Simulation
Wavenumber / cm-
A
bsor
banc
e / 1
0-
2. IR absorption spectrum of CH2IOOCH2IOO ν4 ν5 ν7
Expt. 1233.6 (27) 1228 (6) 919 (13)
p-H2 Matrix 1231.8 (53) 1225.6/1226.5 (19) 917.7 (50)
Theo. 1235 (28) 1231 (35) 901.4 (50)
22
Thanks for your attention!
Acknowledements:• Prof. Yuan-Pern Lee• Kuo-Hsiang Hsu, Yu-Te Su, and all the group members• National Science Council of Taiwan and the Ministry of Education
23
0
1
0
1
0
1
1400 1300 1200 1100 1000 900 8000
1
102 torr
206 torr
A
bsor
banc
e/ 1
0-2
wavenumber / cm-1
303 torr
403 torr
24
Pt = 102 torr
Pt = 206 torr
Pt = 303 torr
Pt = 403 torr
Subtracted spectra: spectra of CH2IOO
1-7 μs, R = 1cm-1
25
0
5
1400 1300 1200 1100 1000 900 800
0
20
40
exptl. spectra403 torr
A
bsor
banc
e/ 1
0-3
simulation cis-CH2IOO
Inte
nsity
/ ar
b. u
nit
Wavenumber / cm-1
Observed spectra of CH2IOO and simulations
ν0 and relative intensity adopted from spectra in p-H2 matrix
1340 1320 1300 1280 1260 1240 1220 1200 1180
0
4
8
Wavenumber / cm-
b
sorb
ance
/ 10
-
26
Observed spectra of CH2IOO and simulations
CH2I2/O2/N2 (0.06/16/94)@308 nm, Pt = 300 torr
27
ν7νC-O/wCH2
ν6νO-O/wCH2
ν3sCH2
ν4rCH2
ν5tCH2
ν8wCH2
Mode description p-H2 matrix
COO deform. 490.2C-I str. 550.5
CH2 wag. 841.6/841.1C-O 917.7O-O 1085.6
CH2 torsion 1225.6/1226.5CH2 rock 1231.8CH2 sci. 1408.9CH2 str. 2982.4
ν: stretch, δ: bend or deformation, δs: scissor, ω: wag, ρ: rock, τ: torsion
28
1450 1400 1350 1300 1250 1200 950 900 850 800
0
1
2
3
4
5
b
sorb
ance
/ 10
-
Wavenumber / cm-
Observed spectra of CH2OO and simulationsCH2OO υ(0.25 cm-1) Normalize
ν4 1285.7 32ν5 1230.7 8
dioxirane υ(0.25 cm-1) ν3 1231.5 23ν7 1213.2 2
CH2IOO υ(0.25 cm-1) ν4 1233.6 5ν5 1228 1
CH2OO υ(0.5 cm-1) Normalizeν4 1285.7 32ν5 1230.7 8
dioxirane υ(0.5 cm-1) ν3 1231.5 15ν7 1213.2 1
CH2IOO υ(0.5 cm-1) ν4 1233.6 27ν5 1228 6
29
0
10
0
3
6
1340 1320 1300 1280 1260 1240 1220 1200 1180 1160
0
1
308 nm40 torr
308 nm300 torr
248 nm95 torr
30
0
20
0
5
10
960 940 920 900 880 860
0
3
308 nm40 torr
308 nm300 torr
248 nm95 torr
0
2
4
950 940 930 920 910 900 890 880 870 8600
2
4
A
bsor
banc
e / 1
0-
Wavenumber / cm-
Expt. 1 cm-1
0
2
4
950 940 930 920 910 900 890 880 870 8600
2
4
A
bsor
banc
e / 1
0-
Wavenumber / cm-
31
Spectroscopic analysis of ν6
O-O stretching (ν6) a-type:b-type = 0.98:0.02
Δ𝜈=2𝐵′+2 Δ 𝐵( 𝐽+1) Δ𝜈=¿
31
𝜈 𝐽 ,𝐾=𝜈0+ [ Δ 𝐴− Δ 𝐵 ] 𝐾2+∆𝐵𝐽 ( 𝐽+1 )
Δ B < 0
Δ A -Δ B <0, from Q
cm-1 ground ν6
ν 909.2
A 2.59355 2.57880
B 0.41580 0.41330
C 0.35762 0.35539
Expt. 0.25 cm-1
0
2
4
0
2
4
Simulation
RQ6RQ
5RQ
4RQ
3PQ
5PQ
6PQ
7PQ
8
5 10 15 20 25 300.55
0.60
0.65
0.70
0.75
R branch
spac
ing
J+10 5 10 15 20 25
0.81
0.84
0.87
P branch
spac
ing
(2J+1)