The origin of the infrared multiphoton induced luminescence of chromyl chloride

We have studied systematically the luminescence induced when CrO ₂Cl₂ is infrared multiphoton excited by a moderate fluence (0-15 J/cm²) CO₂ laser. This includes the dependence of the full luminescence spectrum on CO₂ laser fluence, and for various spectral regions of the luminescence their dependence on CO₂ laser wavelength and fluence, their intramolecular decay rates, and using a time-of-flight technique the translational temperatures associated with their sources. These measurements show that two species contribute to the luminescence. In addition, a chemical identification of these species is made by preceding the IR laser pulse with a UV laser pulse to photochemically prepare the CrO₂Cl fragment, and isolate its contribution to the luminescence. Strong evidence is obtained in support of both CrO₂Cl fragment and CrO₂Cl₂ parent contributions to the luminescence. The relative contributions of the two to the luminescence and an absolute yield for the IR multiphoton induced dissociation of CrO ₂Cl₂ into CrO₂Cl as functions of CO₂ laser fluence are estimated.