A Mousetrap in the Atomic Nucleus: Reading Thorium with Ejected Electrons ⚡ экспресс
For the first time, laser-induced conversion electron Mössbauer spectroscopy of the nuclear isomeric state ²²⁹Th has been demonstrated. Excitation of the 8.4 eV nuclear transition in a thin ThO₂ sample (band gap ~6 eV) causes rapid decay via internal conversion with electron emission, which is detected to obtain spectroscopic data. Unlike fluorescence spectroscopy, the method is applicable to materials with a work function below the nuclear transition energy, expanding the class of systems that can be studied. Using ThO₂ composed of spinless isotopes and reducing the isomer lifetime to ~10 μs through internal conversion cuts the interrogation time of nuclear clocks by ~10⁸ times and potentially lowers clock instability by four orders of magnitude.
Inside thorium-229’s nucleus lies a hair-trigger mousetrap. When struck by a laser, it normally snaps shut, releasing a twinkle of ultraviolet light. But in many crystals, that light is smothered—like a bell wrapped in cloth—making the trap seem silent. Now, physicists bypass the light entirely: they detect the snap itself by catching the electron that gets kicked out when the trap springs. This method, internal conversion spectroscopy, reads the nuclear state even through materials that would block the light.
The payoff is speed. By crafting the crystal from a specific isotope of thorium, the trap snaps in just 10 microseconds—a hundred million times faster than waiting for the light. A nuclear clock based on this electron readout could become 10,000 times more stable, potentially losing less than a second over the age of the universe. Such a clock would test whether the speed of light is truly constant and probe the Standard Model of physics for cracks.
🎯 The energy needed to spring the mousetrap is a mere 8.4 electron volts, easily delivered by a laser—most nuclear transitions demand monstrous particle accelerators.