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Abstract

Seven rotational and fine-structure transitions of the deuterated molecular ion SD+ in the X-3 Sigma(-) ground electronic state have been measured in the 271-863 GHz region in the laboratory. This ion has been produced by direct-current glow discharge using a mixture of D2S and argon in a free space cell in a temperature range of -140degree celsius to -160degree celsius. The rotational, centrifugal distortion, spin-spin interaction, and hyperfine constants have been determined; the standard deviation of the residuals in the fitting is 109 kHz. The set of obtained spectroscopic parameters provides a list of accurate submillimeter rest frequencies of SD+ for astronomical detection. We have investigated lines of SD+ toward the quasar PKS 1830-211 using the Atacama Large Millimeter/submillimeter Array archive, as the z = 0.89 molecular absorber exists in front of this quasar. A data set covering the 297 GHz region includes the N-J = 2(3)-1(2) transition at 561 GHz due to redshift, providing an upper limit of the column density N-tot = 3 x 10(12) cm(-2) for SD+.