The apparent detachment energy at the ³P₂ threshold, for mean photoelectron kinetic energies ranging from 33.8 to 70.7 m⁻¹

Figure 3. The apparent detachment energy at the ³P₂ threshold, for mean photoelectron kinetic energies ranging from 33.8 to 70.7 m⁻¹. Open circles, triangles and diamonds are data taken at 183, 267 and 364 V m⁻¹, respectively. Extrapolation down to = 0 produces a measurement of the ³P₂ PT, 1239 711.8(11) m⁻¹. The continuous line is the linear regression of the data, the nearly zero slope of which reveals that the error on the electric field value was probably lower than 0.5%. Larger error bars for lower electric fields are due to the larger perturbation of electron interferograms by spurious electric fields in the vicinity of the electron detector.

Abstract

A beam of Sn⁻ ions produced by a caesium sputtering ion source is photodetached in the presence of an electric field, with a single-mode ring Ti:Sa laser. The laser wavelength, about 806 nm, is set just above the excitation threshold of the ³P₂, highest fine-structure sublevel of the ³P ground-term of Sn I. The photoelectron energy is measured by photodetachment microscopy. The measured photodetachment threshold is 1239 711.8 (11) m⁻¹, from which an improved value of the electron affinity of tin can be deduced: 896 944.7 (13) m⁻¹ or 1.112 070 (2) eV.