How light is scattered by the metallic nanoparticles on the surface of a daguerreotype determines the characteristics of its image, such as shade and color.

Andrea E. Schlather, Paul Gieri, Mike Robinson, Silvia A. Centeno, and Alejandro Manjavacas, “Nineteenth-century nanotechnology: The plasmonic properties of daguerreotypes” in PNAS (Proceedings of the National Academy of Sciences). Online first published June 10, 2019 Edited by Catherine J. Murphy, University of Illinois at Urbana–Champaign, Urbana, IL, and approved May 2, 2019.

As seen on various websites, The Metropolitan Museum of Art (The Met) and The University of New Mexico have announced groundbreaking new findings after a two-year study of the plasmonic properties of daguerreotypes. Using atomic force microscopy and scanning electron microscopy, together with numerical calculations, the team of scientists from The Met and UNM, in collaboration with Century Darkroom, Toronto was able to determine how the light scattered by the metallic nanoparticles on the surface of a daguerreotype determines the characteristics of its image, such as shade and color.

Daguerreotypes, among the earliest photographs of the 19th century, owe their incredible optical properties, image resolution, and dynamic range to light scattering produced by metallic nanostructures on their surface. Here we provide a detailed experimental and theoretical analysis on how the material composition, morphology, and dimensions of these nanostructures determine the characteristics of the daguerreotype image. Our results provide a scientific understanding of the unique optical effects of these artworks and therefore, in addition to providing valuable insight for developing preservation protocols, can inspire additional approaches for color printing, where nanostructures are directly manufactured by light.

Abstract: Plasmons, the collective oscillations of mobile electrons in metallic nanostructures, interact strongly with light and produce vivid colors, thus offering a new route to develop color printing technologies with improved durability and material simplicity compared with conventional pigments. Over the last decades, researchers in plasmonics have been devoted to manipulating the characteristics of metallic nanostructures to achieve unique and controlled optical effects. However, before plasmonic nanostructures became a science, they were an art. The invention of the daguerreotype was publicly announced in 1839 and is recognized as the earliest photographic technology that successfully captured an image from a camera, with resolution and clarity that remain impressive even by today’s standards. Here, using a unique combination of daguerreotype artistry and expertise, experimental nanoscale surface analysis, and electromagnetic simulations, we perform a comprehensive analysis of the plasmonic properties of these early photographs, which can be recognized as an example of plasmonic color printing. Despite the large variability in size, morphology, and material composition of the nanostructures on the surface of a daguerreotype, we are able to identify and characterize the general mechanisms that give rise to the optical response of daguerreotypes. Therefore, our results provide valuable knowledge to develop preservation protocols and color printing technologies inspired by past ones.

See also Mudd Library’s 2000 online exhibition of their historic Princeton daguerreotypes: