Group/T

A/180˚C

1

2

3

nm

93

53

39

Surface ratio (nm/nm2)

0.0091

0.0166

0.0218

B/200˚C

1

2

3

nm

121

112

83

Surface ratio (nm/nm2)

0.0075

0.0072

0.0114

C/220˚C

1

2

3

nm

102

113

71

Surface ratio (nm/nm2)

0.0068

0.0071

0.0132