Science & Technology (Commonwealth Union) – Microscopy has always played a key role in revolutionizing science. The ability to evaluate matter that is not visible to the naked eye has helped gain a deeper understanding of the world around us.
Scientists at the University of Maryland (UMD) have formed a new method for identifying extremely small surface changes in materials by rapidly oscillating a microscopic tip back and forth. The technique reveals how a material’s surface responds when it bends or expands after absorbing infrared light.
In a study published on Aug. 5, 2026, in the journal Nature Communications, the team introduced a high-resolution imaging approach known as infrared torsional force microscopy (TFM-IR). The technology enables scientists to examine material surfaces with almost nanometer-level accuracy as they stretch and deform in response to infrared radiation. This type of invisible light is absorbed by many chemical bonds, causing them to vibrate. TFM-IR is the first method capable of precisely measuring both upward-and-downward and side-to-side vibrations created by light exposure.
Min Ouyang, a professor of physics at UMD and a researcher with the Quantum Materials Center and Maryland NanoCenter, who headed the project indicated that they have overcome a long-standing limitation in optical imaging.
He pointed out that many advanced quantum materials gain their unique properties from changes occurring across distances of only a few nanometers or even smaller scales—details that conventional optical microscopes are unable to capture.
The new technique developed by Ouyang and his team builds on atomic force microscopy (AFM), a technology introduced in the 1980s that has become a widely used tool for examining material surfaces with exceptional accuracy. Unlike conventional microscopes that rely on light and lenses to create images, AFM operates more like the sense of touch. It uses an extremely small probe that moves across a surface, detecting forces caused by tiny elevations and structures.
With the ability to identify features smaller than a nanometer, AFM can, in ideal conditions, even distinguish individual atoms. The researchers’ infrared-enhanced version expands this capability by allowing scientists to observe minute light-driven movements and structural changes at unprecedented resolution.
AFM on its own is limited to mapping a surface’s physical structure. It can detect variations in height, showing where a surface rises or dips, but it cannot reveal the chemical identity of the material being examined. To determine a sample’s composition, researchers typically use infrared light to stimulate vibrations within the material and then measure the resulting surface movements with the AFM tip. Since chemical bonds interact with infrared light in distinct and predictable patterns, combining AFM with infrared analysis allows scientists to identify molecular fingerprints, helping confirm a material’s composition or uncover the presence of unwanted substances.
“If you shine some light on your sample, you’re going to get some very slight thermal expansion,” explained Yonatan Gazit, who is a graduate student in physics at UMD who is the lead author of the new paper as well. “AFM is essentially measuring that thermal expansion to understand how well your sample is absorbing or interacting with the light.”
Modern AFM systems use a finely pointed tip positioned above a sample and attached to the bottom of a slender cantilever. Electronic controls move the cantilever rapidly in a vertical motion, causing the tip to lightly tap the sample surface at a consistent frequency. This tapping motion prevents the tip from becoming trapped by surface features such as ridges, reducing the risk of damaging the material under examination. It also improves the detection of IR induced vibrations by enabling the tip motion closely matched to the response frequency of the material. As the tip passes over the sample variations in the motion of the material change the regular tapping rhythm. Using laser light shined on the top of the cantilever to track its movement, scientists can find these tiny changes in tapping behaviour.
