ESR studies of the formyl radical in a CO matrix: Magnetophotoselective photolysis and thermally activated rotations

摘要: Photolysis of the formyl radical (HCO) in a CO matrix at 13 K by yellow light (λ>500 nm) polarized with its electric vector parallel to an external magnetic field (HDC) is orientationally selective, as shown changes powder ESR spectrum radical. The depleted orientation cyclic photolysis [HCO→hν H+CO; H+ (a different CO)→(randomly oriented HCO)] (HCO plane) ⊥ HDC, showing that largest component optical transition moment perpendicular HCO plane, predicted theory for nonrotating HCO. Around 25 part photoinduced orientational anisotropy lost due incipient rotation about axis close bond, but remaining persists higher temperatures (∼40 K), where it decays only slowly. 35 this becomes fast enough yield pseudoaxially symmetric g∥=1.9973,g⊥=2.0021, and A∥=A⊥=383.0 MHz. closest significantly from minimum inertial...