The title compounds, acyclic phenyl nitrones with functional groups, cyclic dinitrones with conjugated or isolated double bonds, and imidazoline nitrones are studied as spin traps (ST) for short-lived free radicals (R) generated photochemically in solution and in the gas phase. New STs are efficient in trapping OH, hydroxyalkyl, or HO2 radicals. EPR spectra of the spin adducts (SA) of studied dinitrones are triplets of doublets characteristic of the nitroxides with one radical center. Imidazoline ST with amino nitrogen exhibits pH-dependent hyperfine splittings of its SAs. Some spin traps were shown to be efficient in detecting R in the atmospheric experiments.