Knowledge Bank

Chemiluminescence emission has been observed from IF in a flow of $I2$ and $F2$ at a cell temperature of $400\circ$C. Spectra have been recorded under medium resolution from 470 to 750 nm, and structure originating from the $A3\Pi (1)$ state and terminating in the ground, $X\Sigma +$ state has been observed. Bandheads in progressions based on $0\le v\prime \le 15$ and $0\le v\prime \prime \le 5$ have been measured and assigned. A new vibrational numbering for the A state is proposed which leads to improved molecular constants: $\tau e=(14936\pm 2)cm-1,we=(386.3\pm 0.8)cm-1,wexe=(2.51\pm 0.11)cm-1,weze=(-0.056\pm 0.005)cm-1,De=(7884\pm 300)cm-1$. The IF(A) emission showed a strong dependence on cell temperature with the most prominent features appearing at $400-500\circ$C. These results are explained on the basis of the rapidity of electronic quenching at the lower cell temperatures.