Observing a coherent superposition of an atom and a molecule

We demonstrate that it is possible, in principle, to perform a Ramsey-type interference experiment to exhibit a coherent superposition of a single atom and a diatomic molecule. This gedanken experiment, based on the techniques of Aharonov and Susskind [Phys. Rev. 155, 1428 (1967)], explicitly violates the commonly accepted superselection rule that forbids coherent superpositions of eigenstates of differing atom number. A Bose-Einstein condensate plays the role of a reference frame that allows for coherent operations analogous to Ramsey pulses. We also investigate an analogous gedanken experiment to exhibit a coherent superposition of a single boson and a fermion, violating the commonly accepted superselection rule forbidding coherent superpositions of states of differing particle statistics. In this case, the reference frame is realized by a multimode state of many fermions. This latter case reproduces all of the relevant features of Ramsey interferometry, including Ramsey fringes over many repetitions of the experiment. However, the apparent inability of this proposed experiment to produce well-defined relative phases between two distinct systems each described by a coherent superposition of a boson and a fermion demonstrates that there are additional, outstanding requirements to fully lift the univalence superselection rule.

The application of X-ray photoelectron spectroscopy to clay science

Photo-electron spectroscopy as an analytical tool has only received limited interest in the field of mineral science. Photo-electron spectroscopy, together with Auger electron spectroscopy, gives information about the positions of the energy levels in atoms or molecules. Application of this technique on solid materials will result in information of the band structure of these materials. The principle of photo electron spectroscopy is rather simple: photons with certain energy (wavelength) are allowed to collide with an atom, molecule or a solid material. These photons can then interact with electrons present in the atoms and one of these electrons can be excited from its orbital resulting in a situation similar to a free electron plus a positively charged atom or molecule.