Supplementary Material
Infrared absorption of gaseous CH2BrOO
detected with a step-scan Fourier-transform absorption spectrometer
Yu-Hsuan Huanga) and Yuan-Pern Leea), b) *
a)
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung
University, Hsinchu 30010, Taiwan
b)
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
(Received xx August 2014 accepted xx xxxx 2014)
Running title: IR absorption of CH2BrOO
Key words: IR spectroscopy, CH2BrOO, bromomethylperoxy, CH2Br, free radical
a) Author
to whom correspondence should be addressed. Electronic mail:
yplee@mail.nctu.edu.tw; FAX: 886-3-5713491.
Comparison of rotational parameters of syn-CH281BrOO and anti-CH281BrOO in their
ground and vibrationally excited states predicted with the B3LYP/aug-cc-pVTZ method is
shown in Table SI. Comparison of rotational parameters and type ratios of CH2BrO and
CH2BrOOBr in their ground and vibrationally excited states predicted with the B3LYP/augcc-pVTZ method is presented in Table SII.
Figure S1 shows the displacement vectors and directions of dipole derivatives for all
vibrational modes of syn-CH2BrOO predicted with the B3LYP/aug-cc-pVTZ method. Figure
S2 shows the simulated rotational contours for 4 and 8 modes of syn-CH2BrOO;
individual bands types as well as resultant rotational contours are presented.
TABLE SI. Comparison of rotational parameters of syn-CH281BrOO and anti-CH281BrOO
in their ground and vibrationally excited states predicted with the B3LYP/aug-cc-pVTZ
method.
syn-CH281BrOOa
a
anti-CH281BrOOb
i
A'/A"
B'/B"
C'/C"
A'/A"
B'/B"
C'/C"
1
0.9979
1.0017
1.0012
0.9991
1.0008
1.0008
2
0.9985
1.0005
1.0004
0.9974
1.0004
1.0005
3
1.0015
0.9985
0.9992
0.9970
0.9994
1.0002
4
0.9976
0.9990
0.9987
0.9966
0.9996
0.9983
5
0.9961
1.0010
1.0006
0.9927
1.0005
1.0006
6
0.9946
0.9992
0.9987
0.9992
0.9978
0.9982
7
0.9949
1.0006
0.9996
1.0076
0.9968
0.9963
8
1.0001
0.9946
0.9958
0.9865
0.9975
0.9975
9
1.0017
0.9936
0.9945
0.9944
0.9968
0.9960
10
0.9976
0.9998
0.9984
1.0096
0.9984
0.9983
11
0.9991
0.9986
0.9986
1.0171
0.9998
0.9992
12
1.0223
0.9957
0.9965
0.9493
1.0029
1.0053
For syn-CH281BrOO, A" = 0.5670 cm1, B" = 0.0726 cm1, C" = 0.0678 cm1 for  = 0 and
Ae" = 0.5664 cm1, Be" = 0.0732 cm1, Ce" = 0.0684 cm1 for the equilibrium geometry.
b
For anti-CH281BrOO, A" = 1.2048 cm1, B" = 0.0604 cm1, C" = 0.0582 cm1 for  = 0 and
Ae" = 1.2370 cm1, Be" = 0.0607 cm1, Ce" = 0.0585 cm1 for the equilibrium geometry.
TABLE SII. Comparison of rotational parameters and type ratios of CH2BrO and
CH2BrOOBr in their ground and vibrationally excited states predicted with the B3LYP/augcc-pVTZ method.
CH2BrOa
CH2BrOOBrb
a
i
harmonic
anharmic.
2
1300 (65)
1246
1.0001 0.9997 1.0014
a:b = 44:56
4
1115 (53)
1088
0.9984 0.9942 0.9930
a:b = 96:4
4
1288 (36)
1261
0.9989 0.9994 0.9989 a:b:c = 55:40:5
5
1258 (21)
1229
0.9987 1.0004 1.0004 a:b:c = 73:20:7
6
1041 (156)
1009
0.9956 1.0016 1.0003 a:b:c = 88:10:2
7
922 (8)
904
0.9992 0.9979 0.9982 a:b:c = 82:2:16
A'/A"
B'/B"
C'/C"
type ratio
For CH2BrO, A" = 1.6133 cm1, B" = 0.1227 cm1, C" = 0.1165 cm1 for  = 0 and Ae" =
1.6107 cm1, Be" = 0.1237 cm1, Ce" = 0.1175 cm1 for the equilibrium geometry.
b
For CH2BrOOBr, A" = 0.1323 cm1, B" = 0.0262 cm1, C" = 0.0224 cm1 for  = 0 and Ae" =
0.1312 cm1, Be" = 0.0267 cm1, Ce" = 0.0227 cm1 for the equilibrium geometry.
1, a:b:c = 0.33:0.35:0.31
2, a:b:c = 0.08:0.88:0.04
, a:b:c = 0.02:0.29:0.69
4, a:b:c = 0.78:0.2:0.02

5, a:b:c = 0.2:0.18:0.63

6, a:b:c = 0.75:0.11:0.14


7, a:b = 0.98:0.02
8, a:b:c = 0.92:0.02:0.06

9, a:b:c = 0.83:0.16:0.01

10, a:b = 0.78:0.22

11, a:b:c = 0.3:0.1:0.6

12, a:b:c = 0.18:0.63:0.19
Fig. S1. Displacement vectors (thin arrows) and directions of dipole derivatives (thick arrows)
for all vibrational modes of syn-CH2BrOO predicted with the B3LYP/aug-cc-pVTZ method.
Molecular rotational axes are represented as arrows with labels.
v4
3
v6
2
4
a-type
2
6
a-type
1
1
0
0
b-type
b-type
1
Intensity / arb. unit
Intensity / arb. unit
2
1
0
c-type
5
0
3
3
c-type
0
a:b:c = 0.78:0.2:0.02
2
a:b:c = 0.75:0.11:0.14
2
1
0
0
1300
1290
1280
1270
wavenumber / cm
1
1260
1250
1110
1100
1090
v7
2
1080
wavenumber / cm
1070
1
v8
7
a-type
4
8
a-type
2
0
0
b-type
b-type
1
Intensity / arb. unit
Intensity / arb. unit
1
c-type
3
0
2
2
c-type
0
4
a:b= 0.98:0.02
a:b:c = 0.92:0.02:0.06
2
0
980
0
970
960
wavenumber / cm
950
1
940
910
900
890
880
wavenumber / cm
870
860
1
Fig. S2. Simulated rotational contours for 4 and 8 modes of syn-CH2BrOO. (a) type a; (b)
type b; (c) type c; (d) resultant rotational contours according to the weighting factors
determined according to the projections of the predicted dipole derivatives onto axes a, b and
c.