Chemiluminescence of CaCl From the Ca+Cl₂ Reaction in Argon Matrix

Visible chemiluminescence in the 5800‐6600 Å region was observed from the Ca+Cl₂ reaction in an argon matrix. The longer wavelength doublet progression is assigned as the A²Π_{3/2, 1/2}→X²Σ⁺ transition of CaCl, with v₀₀= 16189 and 16126 cm⁻¹, respectively. Emission from the vibrationally excited v' = 1 level of the A state was also observed. This is the first observation of resolved spin‐orbit components in matrix chemiluminescent reactions. The progression with v₀₀=16855 cm⁻¹ was assigned as the B²Σ⁺→X²Σ⁺ transition of CaCl. Both transitions showed very small matrix shifts in the T₂ values. A weak band at 17185 cm⁻¹ was assigned as either the E²Σ→B²Σ⁺ or the a⁴Σ⁺→A²Π transition of CaCl. Ca atomic emission at 4232 and 6574 Å was also observed and it was attributed to the energy transfer processes from excited CaCl radicals.