Study on the role of the cool body for the enhancement of sulphur diatomic molecular emission in a hydrogen flame with a multi-channel spectral analyser Original Research Article

Change in the emission spectrum of diatomic sulphur molecule derived from a sulphur containing compounds in a hydrogen flame is measured with a multi-channel spectral analyser. The emission appears with introducing a cool body to the flame. The intensity decreases with time, while temperature of the body increases. It is expected that the introduction of a cool body to a flame suppresses the pre-dissociation of the excited diatomic sulphur molecules by collisional de-activation, and the possibility is discussed. Since the ratio of the number of molecule in the ν′=1 to that in the ν′=0 increases with increasing the ambient temperature near the body, it is concluded that the excited sulphur molecules are deactivated by collision with other molecules to the lower vibrational levels in the excited state. But, it is also noted that the collisional deactivation occurs even without the cool body and the S2 emission from a CS2 flame is not enhanced with the cool body. It is concluded that the enhancement effect observed in a hydrogen flame is not attributed to the suppression on the pre-dissociation of the excited molecules.