Figure 2: Time-resolved measurement in the KDTL interferometer (KTDLI).
From: Coherence in the presence of absorption and heating in a molecule interferometer
An effusive molecular beam leaves an oven with temperature T0. Cross correlating a pseudo-random sequence of openings in a chopper wheel with the arrival time of molecules at the detector provides time-of-flight information, and therefore velocity resolution. The KDTLI is a three grating, near-field matter-wave interferometer. G1 and G3 are material gratings, whereas G2 is formed from a standing light wave. Adjacent gratings are separated by a distance of L. All three have a period d=266 nm and the material gratings have an opening fraction of f∼0.42. Sinusoidal interference patterns in the molecular density distribution are revealed by translating G3 laterally in front of a quadrupole mass spectrometer (QMS) positioned at a distance LC after the chopper wheel. Some particles absorb one or more photons in the light grating resulting in an internal temperature increase, illustrated here by a change in colour.
