The Abdus Salam International Center For Theoretical Physics
Quantum cartography: scientists decipher ice's subatomic secrets to predict climate change and cosmic origins
Abdus Salam International Theoretical Physics Centre
A forty-year-old puzzle regarding how ice interacts with light has been solved, connecting subatomic physics to global environmental science. This groundbreaking theoretical framework for ice photochemistry was developed by teams from the Abdus Salam International Centre for Theoretical Physics (ICTP) and the University of Chicago Pritzker School of Molecular Engineering (UChicago PME). They used quantum mechanical simulations. The discovery illuminates Earth's diminishing permafrost's chemical stability and the prospect of life on distant ice worlds. It was published in late 2025 in PNAS.
“Ghost” in Frozen Lattice
This investigation was inspired by the 1980s finding of the “ghost” in ice. According to scientific investigations, ice samples absorbed particular wavelengths after a few minutes of UV light exposure, but after several hours, they absorbed different wavelengths. This meant that the light was changing the ice's chemical makeup over time, but ordinary observational devices couldn't see it.
According to ICTP scientist and research lead author Marta Monti, “Ice is deceptively difficult to study.” Physical testing are often limited because light impacting ice generates a chaotic cascade that splits molecules, breaks chemical bonds, and forms charged ions, changing the ice's properties in real time. These physical limits were overcome using quantum simulation modelling tools developed to study materials for next-generation quantum technology.
Four Scenarios for Simulating Imperfection
Instead of treating ice as a static, homogenous block, principal author and UChicago Liew Family Professor Giulia Galli used these simulations to change it subatomically. To study how structural “messiness” affects light absorption, they meticulously generated four chemical scenarios:
A hypothesised “perfect” crystal lattice with all water molecules aligned is called defect-free ice.
Water molecule absences produce lattice holes.
Hydroxide Ions: Crystal exposure to negative ions.
Bjerrum Defects: Hydrogen bonding breaks when two or no hydrogen atoms are placed between two oxygen atoms.
The scientists observed that each imperfection has a “optical signature” like a chemical fingerprint. They found that hydroxide ions explained the initial UV absorbance shifts identified in 1980s studies, whereas Bjerrum defects explained the more dramatic changes after extended exposure. This accuracy lets scientists utilise light-absorption patterns to find precise defects in ice samples.
Trapped Electrons and Molecular Cascade
The simulations showed the UV-induced molecular cascade in high resolution. As light hits ice, water molecules split into free electrons, hydroxyl radicals, and hydronium ions. These electrons' "fate" depends on ice structure, the scientists observed.
Electrons can move freely in a perfect lattice, but they get “trapped” in microscopic cavities in “messy” ice with defects. Once trapped, these electrons drastically change the ice's light interactions, creating a self-modifying feedback loop that drives further chemical reactions. Professor Galli says this level of precision in recreating UV light-ice interaction has never been achieved.
Warming Earth Implications
For climate scientists, “quantum codes” are immediately useful. Global warming may release massive amounts of greenhouse gases like carbon dioxide and methane from permafrost earth that has been frozen for millennia.
According to Professor Galli, different types of Earth ice trap these gases. Light or small temperature rises break ice and liberate its contents. By understanding molecular ice disintegration quantum signatures, scientists may better model permafrost degradation and global warming.
Astrochemistry: Finding Life in the Cold
The view from beyond the atmosphere is crucial for astrochemistry. Ice, found in comet tails, Saturn rings, and moons like Europa and Enceladus, is one of the universe's most abundant components. Constant stellar UV radiation bombards these heavenly phenomena.
The UChicago and ICTP studies will help astronomers interpret light signals from these distant worlds. By tracing chemical reactions in alien ice, researchers may locate life's chemical precursors.
Future: The “Melt Layer” and Beyond
The team is now studying the “melt layer” as its next frontier. This is the extremely thin liquid water layer covering ice. They want to explore how solid-to-liquid transitions complicate quantum interactions and gas release.
The team is creating new physical metrics with experimentalists to test computational predictions. Yu Jin, a co-author and former UChicago doctorate student, says computationally isolating chemical reactions provides control that physical laboratories cannot.
These scientists solved a long-standing conundrum and developed a key road map for planetary science and climate resiliency by exploring the subatomic core of frozen water.
