{"id":495268,"date":"2026-06-12T01:54:12","date_gmt":"2026-06-12T01:54:12","guid":{"rendered":"https:\/\/www.newsbeep.com\/ie\/495268\/"},"modified":"2026-06-12T01:54:12","modified_gmt":"2026-06-12T01:54:12","slug":"light-as-a-brake-newsportal","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/ie\/495268\/","title":{"rendered":"Light as a Brake | Newsportal"},"content":{"rendered":"

Light is expected to heat particles up or set them in motion. However, an interdisciplinary team at Ruhr University Bochum, Germany, has now proven the opposite. In aqueous solution, fluorescent carbon nanotubes move much slower once they are irradiated with light. During this process, the diffusion constant decreases with light intensity, an effect linked to direct coupling between electrons in the solid and the molecules of the liquid. The research teams of Sebastian Kruss, Marialore Sulpizi, and Martina Havenith describes the hitherto unknown phenomenon in the science journal Nature from June 10, 2026.<\/a> \u201cThis discovery of light-induced quantum friction fundamentally changes our understanding of interfacial processes,\u201d says Kruss.<\/p>\n

Experiment: light as an invisible brake<\/p>\n

The nanotubes used in the experiments consist of a carbon mesh and are 100,000 times thinner than a human hair. They fluoresce when irradiated with visible light.<\/p>\n

The team observed the movement of the nanotubes under the microscope. Once the tubes were excited via light, they behaved as though the surrounding water had suddenly become more viscous. \u201cOur experiments show that the diffusion decreases when we increase the light intensity,\u201d says Kruss, Professor of Physical Chemistry. \u201cWhat\u2019s fascinating is that this effect vanishes entirely when we use nanotubes in which the electronic excitations that lead to the fluorescence \u2013 known as excitons \u2013 are slowed down at defects. This means it is the mobility of the excitons along the nanotube that is in direct exchange with the environment and creates this decelerating effect.\u201d<\/p>\n

Theory: understanding the transfer of momentum<\/p>\n

Numerical calculations were required in order to understand how an exciton inside a nanotube can decelerate the movement of the entire object in water. To do this, the team used atomistic simulations to make the processes on the interface visible. \u201cBy doing so, we were able to show that the fluctuating dipole moments of the excitons in the nanotubes directly couple with the collective movements of the water molecules,\u201d explains Professor of Theoretical Physics Marialore Sulpizi. \u201cA tiny but measurable transfer of momentum takes place. The water is not a smooth medium for the illuminated nanotube, but instead there is resistance on the surface that slows the movement.\u201d<\/p>\n

Spectroscopy: water as an active partner<\/p>\n

One of the key topics that the Excellence Cluster RESOLV (Ruhr Explores Solvation) in Bochum is working on is the fact that water is much more than just a passive solvent. By using terahertz (THz) spectroscopy, the team was able to experimentally demonstrate the immediate coupling between the nanotube and the water.<\/p>\n

\u201cWith the THz spectroscopy, we were able to determine how the friction and energy dissipation into water occur in real time after excitation of electronic states of the nanotube,\u201d says Professor Martina Havenith, spokeswoman for RESOLV. \u201cIt is a textbook example of how solvation interactions with the environment dominate physical properties like friction. This knowledge that we can control the friction at the interface with the liquid via electronic excitation in the solid, opens up entirely new doors in materials science and nanotechnology.\u201d<\/p>\n

The discovery of light-induced quantum friction shows that the boundaries between solid physics and liquids blur at the nano-level. Controlling this friction with light offers potential for applications in which transport processes on very small length scales have to be precisely steered.<\/p>\n

Cooperation partners\n <\/p>\n

In addition to research groups from Ruhr University Bochum, researchers from the Fraunhofer Institute for Microelectronic Circuits and Systems IMS were also involved in the work.<\/p>\n

Funding\n <\/p>\n

The work was funded by the German Research Foundation as part of the Excellence Cluster RESOLV.<\/p>\n

Original publication\n <\/p>\n

Tanuja Kistwal, Krishan Kanhaiya, Martina Havenith, Marialore Sulpizi, Sebastian Kruss et al.: Light-induced quantum friction of carbon nanotubes in water, in: Nature, 2026, DOI: 10.1038\/s41586-026-10632-2<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Light is expected to heat particles up or set them in motion. However, an interdisciplinary team at Ruhr…\n","protected":false},"author":2,"featured_media":495269,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[61,60,248,82],"class_list":["post-495268","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-ie","tag-ireland","tag-physics","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/495268","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=495268"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/495268\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/495269"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=495268"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=495268"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=495268"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}