Formation of 1:1 and 1:2 exciplexes between excited mercury atom and amines in the liquid phase

Abstract

The liquid-phase mercury-photosensitized luminescence of amines has been investigated by a steady-state illumination method over a wide range of concentration of amines at several temperatures. The emission band from an exciplex (HgA*) between an excited mercury atom and an amine molecule was observed at ca. 370 nm in cyclohexane. A new band appeared with diethylamine, dipropylamine, di-2-propylamine and dibutylamine at high concentrations on the long-wavelength side of the band of HgA*, while two new bands appeared for propylamine, butylamine and tert-butylamine at high concentrations. The intensities of the bands observed at high concentrations increased with increasing concentration of the amines. These bands were assigned to two kinds of 1:2 exciplexes (HgA₂^* and HgA₂^**). The enthalpy changes among these exciplexes were estimated from the temperature dependences of the intensity ratios of the emission bands.