Detection of OH and wide HI absorption toward B0218+357

We present deep Giant Metrewave Radio Telescope (GMRT) OH and Westerbork Synthesis Radio Telescope (WSRT) H I absorption spectra of the z = 0.6846 gravitational lens toward B0218 + 357. Both the 1665- and 1667-MHz OH lines are clearly detected for the first time, while a new wide absorption component was detected (at low significance) in the H I spectrum; the OH spectra yielded an OH column density of N-OH = 2.3 x 10(15) cm(2). The ratio of 1667- and 1665-MHz equivalent widths is similar to1.8 while the redshift of peak OH absorption is z = 0.68468 +/- 0.000008 for both lines; this redshift agrees with that obtained from the H I line. The velocity spread (between nulls) of the H I absorption is similar to140 km s(-1), while that of both OH lines is similar to100 km s(-1); the H I and OH spectra are broadly similar in that they each have two principal narrow components and a wide absorption trough. We argue that the wide absorption is likely to arise from source components in the Einstein ring and derive a rotation velocity of similar to150 km s(-1) at a distance of 1.5 kpc from the centre of the z similar to 0.6846 galaxy.