Measurement of the average emission lifetimes of the A 1∑+–X 1∑+ and the orange Arc bands of CaO

Abstract

A photolytic precursor of CaO was formed in the gas-phase by mixing excess Ca vapour with either N₂O or O₂ in a reactor at 810 K. The precursor was photolysed using an ArF excimer laser at 193.3 nm, resulting in strong orange emission between 590 and 630 nm, with a lifetime of 27.8 ± 1.2 ns, and emission beyond 760 nm with a lifetime of 149 ± 11 ns. The former emission is assigned to the orange arc bands of CaO, and the latter to the CaO(A ¹∑⁺–X ¹∑⁺, Δv < 3) bands. Evidence is presented which suggests that the precursor may be the CaO dimer.