I cannot find anything, other than this image and, possibly, the next image about her. I believe she may have been the wife of the Russian Ambassador to France.
From the unofficial Hermitage Web site.
Mme. Vorotsova-Dashkova dresses in luxurious simplicity with a fur-trimmed velvet dress in this 1873 Cabanel portrait. Her sleeves appear to end in fur cuffs.
Keywords: 1873, Cabanel, Elizabeth Vorontsova-Dashkova, straight coiffure, floral headdress, square neckline, modesty piece, fur, elbow length close sleeves, cuffs, necklace, earrings, bracelets, wrap