Kahr group determines crystal structure of herapathite

Professor Bart Kahr and coworkers recently determined the crystal structure of herapathite, a crystal serendipitously discovered in the middle of the 19th Century when iodine was dropped in the urine of a dog that had been fed lots of quinine. Herapathite crystals are remarkably dichroic – they transmit only plane polarized light.  For this reason, Edwin Land used oriented crystals of herapathite for the invention of polaroid which led to the birth of the Polaroid photography empire. Because the structure of herapathite remained unknown, its light absorbing properties were never fully explained, despite the manufacture of mountains of polaroid. Now we understanding that chains of iodine atoms account for the polarized light transmission. This work was published in Science (2009 324: 1407, DOI: 10.1126/science.1173605) and was reported in Nature Materials (2009, 8, 617, doi:10.1038/nmat2499), Chemical and Engineering News (June 22, 2009, p. 43; http://pubs.acs.org/isubscribe/journals/cen/87/i25/html/8725sci3.html), as well as the German daily newspaper Frankfurter Allgemeine Zeitung (July 1, 2009).

Updated on 07/12/2010