Knowledge Bank

The emission spectrum of $I2$ in foreign gases is studied as a function of pressure, temperature, end isotopic species, using a tesla discharge as $source.1$ Evidence is found for at least 12 of the 18 ion-pair states arising from $I-(1S)+I+(3P,1D)$, of which $D1$(2g) appears to be the lowest. The pressure- and temperature-dependent spectra support the suggestion $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ that both the 3400-A system and a broad band near 5000 A originate from this state. High-resolution spectra show discrete structure in electronic bands at 2380 A, 2770 A, and 2880 A, in addition to the well-known F-X (2700 A), D-A(3400 A), and E-B (4300 A) systems. The 2380 system originates from a state near $51700cm-1$ and terminates on the X state near v = 50. The 2770 system, which was previously $analyzed3,4$ as terminating on the X or B state, is now found to involve the A($lu3\Pi$) $state.5$ The 2880 system terminates on a weakly bound lower slate which probably dissociates to ground-stale atoms. Work is continuing on the other electronic bands of the emission spectrum, most of which appear to be diffuse.