INTERESTING LINES IN THE INFRARED SOLAR SPECTRUM .3. A POLARIMETRIC SURVEY BETWEEN 1.05 AND 2.50 MU-M

We present a survey of Stokes I, V and Q in the near infrared spectral range between 1.05 and 2.50 mu m, based on Fourier transform spectrom eter data obtained in a sunspot umbra and in an active region plage. W e discuss the diagnostic potential of a number of lines for studying s olar magnetic features. These include the Ti I multiplet near 22000 An gstrom, the Fe I g = 3 line at 15648.5 Angstrom, He I 10830 Angstrom, high excitation C I lines, as well as CO and CN lines. As an example, we provide the first estimate of the field strength gradient averaged over the height range covered by the photosphere and chromosphere. We also identify lines that show large Stokes V or Q amplitudes and analy ze their profile asymmetries. In our J-band plage spectrum the Stokes V and Q profiles show an extremely large blue-red asymmetry, whose ori gin is not yet clear. As an incidental result we obtain the first meas ured value of the vertical gradient of the magnetic field strength in a plage. Averaged over approximately 1500-2000 km it corresponds to ro ughly 0.6 G km(-1).