Physicists at Göttingen University imaged the three-dimensional wavefunction of a nanometer-sized organic molecule using a lab-based soft-X-ray laser. Published in Nature Communications, the technique overcomes prior synchrotron constraints to resolve atomic-scale features
Overcoming limitations in quantum imaging
In quantum mechanics, subatomic particles such as electrons cannot be pinned down to a single location. Instead, an electron is described mathematically by a wavefunction that dictates probability distributions for its position and momentum:
- Role of molecular orbitals:
- Electron wavefunctions within a molecule, known as molecular orbitals, carry vital structural information that governs how the molecule interacts with light and undergoes chemical reactions.
- The measurement challenge:
- Because a wavefunction is a probability distribution, it cannot be observed or measured directly in a single step.
- Indirect measurement:
- Researchers use photoelectron spectroscopy to measure the momentum of emitted electrons. This captures the amplitude half of the wavefunction without physically altering its quantum state, relying on computer algorithms to reconstruct the missing phase information.
- Synchrotron bottleneck:
- Previously, acquiring enough data to map these wavefunctions in full 3D required long measurement sessions at massive, multi-user synchrotron facilities, making routine lab experimentation impossible.
Innovation via table-top lasers and advanced algorithms
The Göttingen research team bypassed large-scale facilities by pairing a lab-based soft-X-ray light source with optimised reconstruction software.
The setup generates ultrashort extreme ultraviolet light pulses, while a redesigned algorithm reduces the amount of experimental data needed to construct accurate 3D images.
Together, the system resolves spatial details smaller than the distance between neighbouring carbon atoms within a single molecule.
Potential for ultrafast stroboscopic videography
The use of femtosecond light pulses opens opportunities for dynamic quantum measurements. Researchers aim to develop stroboscopic videography to observe wavefunctions changing in real time at quadrillionths of a second. This capability could reveal how molecular orbitals adapt during optical, electronic, or chemical transformations, offering new ways to control chemical interactions at the atomic scale.
