High precision measurement of the ³²SH electron affinity by laser detachment microscopy

The photodetachment microscopy technique, which was previously used with the OH^- molecular anion, is applied successfully to the SH^- ion with a single-mode dye laser. The interferograms of two rotational thresholds corresponding to particular detachment transitions of the SH^-(X¹Σ⁺; v = 0) → SH(X²Π_{3/2, 1/2};v = 0) band have been recorded. With a double-pass scheme of the laser excitation on the ion beam, pairs of interference patterns are obtained, the 2D fitting of which provides us with a new recommendable value of the electron affinity of ³²SH, ^eA = 18669.543(12) cm^-1, i.e., 2.3147282(17) eV. The precision on the determination of ^eA has been increased by three orders of magnitude in comparison with the previous 1981 determination retained by the most recent review on molecular electron affinities.