New cryo-microscope technique reveals atomic secrets of air-sensitive materials without destroying them

A double challenge for next-generation materials

Some of the most promising materials for future technologies share a frustrating trait: they're extremely fragile. Hybrid perovskites, which could revolutionize solar cells, react instantly with oxygen and moisture. Low-dimensional quantum crystals, candidates for future computers, are damaged by the electron beams needed to see their atomic structure.

Studying them has been like trying to photograph a melting ice sculpture—the act of observation destroys the subject.

A team at SUSTech, led by Professor Junhao Lin, has now developed a method that addresses both challenges simultaneously.

"We wanted to see these materials as they truly are, not as they become after air exposure or beam damage," said Lin. "That meant protecting them every step of the way, and completely rethinking how we image them."

Continuous protection from the air

The solution starts before the sample ever reaches the microscope. Inside a nitrogen-filled glovebox, researchers prepare ultra-thin flakes of sensitive materials using a gentle transfer technique. The samples are then sealed in liquid nitrogen and transported to the microscope—still submerged in liquid nitrogen the entire time.

This "cold chain" continues inside the microscope. The samples are loaded under liquid nitrogen, then transferred to the vacuum column without ever warming up or coming into contact with air. For materials that oxidize in seconds, this continuous protection is essential.

Seeing atoms with barely any imaging electrons

But air protection is only half the battle. Once inside the microscope, the electron beam itself can destroy organic and hybrid materials within seconds. Traditional imaging uses high electron doses to get clear pictures—but for these materials, that's lethal.

The team developed a different approach. They use a Cs-corrected cryo-TEM (a high-end microscope that corrects lens aberrations and operates at –190°C) combined with ultra-low electron doses—about one-thousandth of those used in conventional imaging. The raw images are so faint that they look like static noise. But by taking many rapid images and applying sophisticated alignment and filtering techniques, the team extracts the true atomic structure.

They also developed a 3D filtering method that separates real structural information from random noise, exploiting how atoms stay still while noise fluctuates. The result: atomic-resolution images from doses so low the material barely notices the beam.

Two successful test cases

The team demonstrated their method on two notoriously difficult materials.

First, (FB)₂MnCl₄, an organic-inorganic hybrid perovskite. When exposed to air even briefly, it oxidized into featureless grains. With the new system, they resolved individual atomic columns—manganese-chloride octahedra sandwiched between organic layers—at a resolution of 1.56 Ångströms, using a total dose of only 3 electrons per square Ångström.

Second, NbOI₃, a one-dimensional ferroelectric crystal. Previous attempts with standard techniques produced only blurry, amorphous images. Under cryo-protection and low-dose imaging, the team revealed clear chain-like atomic motifs with uniform spacing—exactly matching theoretical predictions.

A general solution for fragile materials

"This isn't just about two specific materials," said Lin. "Many functional materials are designed for their unique properties, but those same properties often make them fragile. Now we have a way to look at them directly and understand how their atomic structure connects to their performance."

The method can be adapted for organic semiconductors, battery materials, low-dimensional magnets, and other sensitive systems. By combining inert-atmosphere protection, cryogenic stability, and smart low-dose imaging, this approach gives materials scientists a new window into the atomic world of fragile matter.

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