From observations of the Sun as a star made at Kitt Peak it is known that MnI 539.5 nm line exhibits unusually big (for a photospheric line) variations during a solar activity cycle. Doyle et al. 2001 suggested that it is because of optical pumping. This work aims particularly to check this hypothesis with help of observations.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html