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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Tzvi Shacham [mailto:shtzvika@netvision.net.il] <br><b>Sent:</b> Wednesday, May 29, 2013 9:26 AM<br><b>To:</b> Etan Ayalon<br><b>Subject:</b> FW: [agade] NEWS: Spotting Ancient Dyes<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal align=right style='text-align:right'><span style='font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'>--------- Forwarded message ----------<br>From: <b>Jack Sasson</b> <<a href="mailto:jack.m.sasson@vanderbilt.edu">jack.m.sasson@vanderbilt.edu</a>><br>Date: 28 May 2013 20:01<br>Subject: [agade] NEWS: Spotting Ancient Dyes<br>To: "The Agade mailing list." <<a href="mailto:agade@listserv.unc.edu">agade@listserv.unc.edu</a>><br><br><br>From <<a href="http://cen.acs.org/articles/91/i21/Laser-Blast-Helps-Spot-Ancient.html" target="_blank">http://cen.acs.org/articles/91/i21/Laser-Blast-Helps-Spot-Ancient.html</a>>:<br>==============================================================<br><br>Laser Blast Helps Spot Ancient Dyes<br><br>Spectroscopy: Laser vaporization improves surface-enhanced Raman<br>spectroscopy for cultural heritage research<br>By Louisa Dalton<br><br>To study the composition of fragile ancient artifacts, scientists<br>often turn to surface-enhanced Raman spectroscopy (SERS), a technique<br>that can identify low levels of small organic molecules, such as dyes.<br>But current SERS methods don’t work with some oily or otherwise<br>insoluble compounds. Now researchers report a a laser vaporization<br>method that allows analysis of previously SERS-incompatible materials<br>(Anal. Chem. 2013, DOI:10.1021/ac400440c).<br><br>In a typical SERS experiment, scientists dissolve a very small sample<br>in a solution containing gold or silver nanoparticles so the sample<br>molecules adsorb onto the nanoparticles. When illuminated with laser<br>light, the metal surfaces greatly amplify the characteristic signals<br>produced by the excited molecules. These signals allow scientists to<br>identify the compounds and measure their concentrations.<br><br>It’s hard to predict how each sample will react with the<br>nanoparticles, says Pablo S. Londero, a cultural heritage scientist at<br>the Metropolitan Museum of Art in New York City. “You never know what<br>an artist put into a material,” he says.<br><br>What’s more, many materials are insoluble or don’t adsorb well to the<br>metal surfaces. For example, Londero and his colleague Marco Leona<br>were studying 3,000-year-old dyed leather from an ancient Egyptian<br>chariot. The dyes sit within the leather’s collagen matrix, making it<br>tricky to prepare a sample for a traditional SERS analysis.<br><br>The researchers thought that a laser pulse might vaporize a pinpoint<br>of the material of interest and that the vaporized material would<br>adsorb to a metal surface more readily. Londero, Leona, and<br>collaborator John R. Lombardi of the City College of New York<br>fine-tuned the idea to come up with a new SERS method that takes about<br>15 minutes to analyze a single sample.<br><br>They put a sample in a small vacuum chamber and use a microscope to<br>choose a part of the sample to hit with an intense laser pulse. The<br>laser vaporizes a few micrometers of the material, which then deposits<br>onto a thin film of silver nanoparticles sitting just above the<br>sample. The scientists then shine another laser on the silver to<br>record the characteristic signals produced by the deposited material.<br><br>The scientists tried out their technique on the dyes embedded in the<br>Egyptian leather. From the spectra, the team confirmed that the<br>pigment is madder lake, a dye made from the madder plant (Rubia),<br>combined with a metal that helps it bind to the leather.<br><br>The setup is clever, says Renato Zenobi, an analytical chemist at the<br>Swiss Federal Institute of Technology, Zurich. He likes that the<br>direct vaporization keeps the whole experiment within one sample<br>holder. But the greatest advantage, he notes, is that the technique<br>produces spectra of completely insoluble materials that are out of<br>reach with typical SERS methods.<br><br><br>Chemical & Engineering NewsISSN 0009-2347Copyright © 2013 American<br>Chemical Society<br><br>--- You are currently subscribed to agade as: <a href="mailto:shamue@gmail.com">shamue@gmail.com</a>. To unsubscribe send a blank email to <a href="mailto:leave-33154490-48877603.01cc728351255d814938115247ab3280@listserv.unc.edu">leave-33154490-48877603.01cc728351255d814938115247ab3280@listserv.unc.edu</a><br>--- To (re-)subscribe please send a blank email to <a href="mailto:listserv@unc.edu">listserv@unc.edu</a>, and write (as subject and in first<br>line): subscribe agade<o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal><br>______________________________________________________________________<br>This email has been scanned by the Symantec Email Security.cloud service.<br>For more information please visit <a href="http://www.symanteccloud.com">http://www.symanteccloud.com</a><br>______________________________________________________________________<o:p></o:p></p></div></body></html>