Vibration-rotation transitions of CO(X
1
Ʃ
+
) have been observed as infrared chemiluminescence from the reactions of O(
3
P) with C
2
H
2
, C
3
O
2
and HC
3
N. The emission spectra, observed from a spherical flow reactor at low pressures (0.1 to 2 Torr) were characteristic for each reaction system, and in some cases depended on the relative flow rates of the reactants and were affected by the addition of atomic hydrogen. These changes in spectral distribution can yield valuable information about the mechanisms of the elementary reactions involved. Thus in the O + C
2
H
2
reaction, the distribution extending to
v
' = 14 which predominates at low fuel flows is associated with the reactions O + C
2
H
2
= CO + CH
2
+ 48 kcal/mol (200 kJ/mol), O + CH
2
=CO + 2H + 73 kcal/mol (306 kJ/mol). An additional distribution extending up to
v
' = 33 (163 kcal/mol, 680 kJ/mol) is observed at high acetylene flows and in the presence of added hydrogen. This is attributed to the reaction O + CH = CO + H + 176 kcal/mol (736 kJ/mol). Similar emission is also observed from the O + C
3
O
2
reaction when atomic hydrogen is added; in its absence, the dominant CO emission comes from levels
v
≼ 8 and is attributed to the reaction O + C
3
O
2
= 3CO+115 kcal/mol (480 kJ/mol).
Intramolecular water-splitting reaction in single collisions of water ions with surfaces