Spectroscopy of Flames;
Luminescence spectra of reactive intermediates

Ágúst Kvaran*,  Árni Hr. Haraldsson, and Thorsteinn I. Sigfusson

Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland



    Luminescence spectra of oxygen rich propane gas flames have been recorded in medium-high resolution. Well separated vibrational bands for electronic transitions in C2, CH and OH are observed. The spectra are found to be rich, both in terms of vibrational and rotational structure. A large number of bandheads with varying intensities are observed in C2(d(3Pg)->a(3Pu)). Bands are found to be degraded toward the blue (C2(d(3Pg)->a(3Pu)), red (CH(B(2S-)-> X(2P)) and OH(A(2S+)->X(2P)))  or to be nearly symmetric in shape (CH(A(2D)->X(2P))). Clear rotational structure with identifiable rotational line series (P,Q and R) are observed for  CH(A->X and B->X). The relative intensities of vibrational bands vary considerably from one system to another. These observations can be used to demonstrate a number of basic principles in quantum chemistry and spectroscopy,  relevant to electronic, vibrational and rotational structure of molecules as well as transition probabilities. Conventional spectra analysis of i) the C2(d->a) vibrational structure and ii) the CH(B-> X) rotational structure are presented.  Furthermore, spectra  simulations of i) the C2(d->a) vibrational- structure and ii) the CH(A->X) rotational structure are described.