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)