News Picks : Two experiments reconstruct wavefunctions of molecular matter
18 December 2013
Ars Technica: Quantum mechanics describes matter and light as having both wave-like and particle-like behaviors. Formulas known as wavefunctions are used to describe the wave-like properties, but it has not been possible to directly measure the wave-like properties of matter. Now two experiments have done so, thus verifying the accuracy of quantum mechanics' theoretical predictions. The first made use of the Stark effect—the change in the wavefunction of an atom or molecule in an electric field, which results in changes to the spectrum of light scattered off the particle. The researchers used laser pulses to induce predetermined energy transitions in individual hydrogen atoms and measured the changes in the scattered light. The result was a graphical map of hydrogen's wavefunction that matched the theoretical predictions. The other experiment used a similar process but applied it to organic molecules bonded to a silver surface. The researchers made iterative measurements of the scattering of photons off the molecules and were similarly able to reconstruct the wavefunctions for the molecules. This makes it possible to verify the calculated wavefunctions of large molecules, because the functions cannot be calculated directly due to the complexity of the molecules.