Photoelectron emission by solvated electrons in liquid ammonia

Photoelectron emission (PEE) by potassium (0.002–3 mole liter−1) and sodium (0.013–0.21 and 7.2 mole liter−1) in liquid ammonia at −60°C was studied from 1.55 to 5.4 eV. The PEE spectrum is composed of the previously reported band with its maximum about 3.2 eV and a new band peaking about 4.6 eV. The highly asymmetric low-energy band is assigned to PEE by solvated electrons. Its interpretation by a recent model for PEE by solutions results in a linear dependence of the range of quasifree electrons in solution on photon energy. The quantum yield appears to be proportional to the square root of the analytical metal concentration up to 0.1 mole liter−1. The 4.6 eV symmetric PEE band is interpreted as the result of bound-bound transitions (similar to β band for F centers) followed by autoionization. Experimental methods are outlined, and their details are available in an unpublished report.