Neal Kline, Meng Huang, and Terry A. Miller
Department of Chemistry and Biochemistry
The Ohio State University
Criegee Intermediate
First proposed by Rudolf Criegee in 1949 as
intermediate in ozonolysis of alkenes.
Formed in the atmosphere and utilized heavily
in organic chemistry to functionalize double
bonds.
Large amounts of research have been focused
on the Criegee intermediate recently.
𝑎 − 𝑋 transition of the Criegee Intermediate
C=1s22s22p2
O=1s22s22p4
3A’
3A
2
9530 cm-1
1A’
1A
1
a. Harding, L. B. and Goddard III, W. A. J. Am. Chem. Soc. 1978, 100, 7180-7188.
b. Wadt, W. R. and Goddard III, W. A. J. Am. Chem. Soc. 1975, 97, 3004-3021.
Sirah dye laser
570-705 nm
20 Hz
~600 mJ/pulse
Nd:YAG: 532 nm
~70-80
mJ/pulse
Raman cell (H2, 300 psi)
Photolysis:
Excimer Laser
KrF, 248 nm
2nd Stokes:
6000-9000 cm-1
~1-2
mJ/pulse
Highly
Reflective
Mirror
(99.995 %)
Highly
Reflective
Mirror
(99.995 %)
Photolyze diiodomethane at 248 nm, one iodine atom dissociates.
CH2I radical reacts with oxygen to give CH2IOO. CH2IOO then
dissociates I atom to give CH2OO.a
We observed our spectrum under conditions of 86.0 torr total
pressure (84.9 torr N2, 0.1 torr CH2I2, 1.0 torr O2) ,which is the
same conditions as Y. P. Lee. b
a. Oliver Welz et al., Science, 335 204, 2012;
b. Su, Y.; Huang, Y.; Witek, H. A. and Lee, Y. P. Science 2013, 340, 174.
Experimental Spectrum
875 cm-1, Typical OO Stretch Frequency
Iodine atom
2P
1/2
2P
3/2
𝐴−𝑋
H2O
Contamination
𝑎−𝑋
Precursor
Absorption
Precursor
Absorption
Comparison of the Spectra for CH2XOO Radicals
Good electronic structure
calculations – FD07,Dawes
Vibrational spectral
analysis– FD06
𝐴-𝑋 T00 Frequency
7383 cm-1
6817 cm-1
6799 cm-1
6908 cm-1
Wavenumber(cm-1)
Mechanism requires libration of I upon reaction of CH2I+O2. Photolysis of
CH2I2 with O2 present shows a nearly 50% increase in I atom signal compared
to the photolysis without O2
a. Huang, H.; Eskola, A.; Taatjes, C. A. J. Phys. Chem. Lett. 2012, 3, 3399.
3.9 x 10-11 cm3molec-1s-1
SO2 is effective Criegee
intermediate scavenger and
reacts very quicklya,b,c, however
reacts very slowly with peroxy
radicalsd,e.
≤1 x 10-16 cm3molec-1s-1
a. D. Stone, M. Blitz, L. Daubney, T. Ingham, and P. Seakins. Phys. Chem. Chem. Phys., 2013,15, 19119-19124.
b. L. Sheps. J. Phys. Chem. Lett., 2013, 4, 4201-4205.
c. O. Welz, J. D. Savee, D. L. Osborn, S. S. Vasu, C. J. Percival, D. E. Shallcross, and C. A. Taatjes. Science, 2012, 335, 204-207.
d. P. D. Lightfoot, R. A. Cox, J. N. Crowley, M. Destriau, G. D. Hayman, M. E. Jenkin, M. J. Rossi, and J. Troe. Atmos. Chem. Phys.,
2006, 6, 3625-4055.
e. C. S. Kan, J. G. Calvert, and J. H. Shaw. J. Phys. Chem., 1981,85, 1126-1132.
Experimental Spectrum of CH2ClOO with SO2
Experimental Spectrum of CH2BrOO with SO2
Experimental Spectrum of the Carrier
Generated by CH2I2/O2 mixed with SO2
Self Reaction?
CH2IO2 + CH2IO2 → 2CH2IO + O2
CH2O2 + CH2O2 → 2CH2O + O2
Reaction Mechanism?
+SO2
We measured the spectrum generated by photolysing CH2I2
precursor mixed with O2 in the NIR region with cavity ringdown
spectroscopy(CRDS).
Spectra evidence show that the carrier of the spectrum is likely
to be CH2IOO. The 𝐴-𝑋 electronic transitions of CH2BrOO and
CH2ClOO were obtained with CRDS in the similar region, which
shows some similarities and difference to the spectrum of
unknown carrier.
Kinetics evidence show that the carrier of the spectrum is
suggestive to be CH2OO, but not definitive. The reaction of the
SO2 with the carrier of the spectrum was studied. The spectrum
of the unknown carrier has a significant decrease in intensity
after mixing the precursor with SO2, while the CH2BrOO and
CH2ClOO are not affected by SO2. Quantitative analyses in
kinetics are also necessary to make the conclusion.
Dr. Terry A. Miller
Dr. Neal D. Kline
Dr. Dmitry Melnik
Dr. Mourad Roudjane
Henry Tran
Dr. Richard Dawes
Phalgun Lolur
Kinetics
If we follow Y. P. Lee’s mechanism, and our upper estimates of the initial
concentration of CH2I and iodine atoms at 1.0E+15, then the expected half-life time
for Criegee is ~ 11 microseconds and for CH2IO2 is about 24 microseconds. The
measured value is about 5 microseconds, which makes it look more like Criegee
rather than peroxy.
CH 2 I  O2  CH 2O2  I
CH 2 I  O2  CH 2O2 I
1.04 1012
4.6 1013
CH 2O2  CH 2O2  2CH 2O  O2
8 1011
CH 2 IO2  CH 2 IO2  2CH 2 IO  O2
9 1011
CH 2 IO  CH 2O  I
105
CH 2O2  I  CH 2 I  O2
5.7 1011
CH 2O2  I  CH 2 IO2
2.6 1011
CH 2 IO2  I  CH 2 IO  IO
4 1011
CH 2O2  I  CH 2O  IO
IO  IO  products
9 1012
1.51010
W.-L. Ting, C.-H. Chang, Y.-F. Lee, H. Matsui, Y.-P. Lee*, and Jim J.-M. Lin*, J. Chem. Phys. 141, 104308 (2014).
R. Atkinson, el al., Atmos. Chem. Phys. 7, 981 (2007)
T. Gravestock, M. Blitz, W. Bloss, and D. E. Heard, ChemPhysChem 11, 3928 (2010)
Kinetics
30
25
ppm/pass
20
15
10
5
0
10
15
20
25
30
Time, s
0.5 Torr of SO2 would “kill” Criegee almost immediately
Even if peroxy does not directly react with SO2, its temporal profile
shows faster decay with the addition of SO2. When Criegee depletes
faster, the peroxy replenishment channel quenches.
CH 2 IO2  SO2  CH 2 IO  SO3
k  1.5 1012
k 0