Energy-dispersive X-ray spectroscopy: Energy-dispersive X-ray spectroscopy (EDS, EDX, or XEDS), sometimes called energy dispersive X-ray analysis (EDXA) or energy dispersive X-ray microanalysis (EDXMA), is an analytical technique used for the elemental analysis or chemical characterization of a sample. It relies on an interaction of some source of X-ray excitation and a sample.Journal of Biological Inorganic Chemistry: Journal of Biological Inorganic Chemistry is a peer-reviewed scientific journal. It is an official publication of the Society of Biological Inorganic Chemistry and published by Springer Science+Business Media.Quantum noise: In physics, quantum noise refers to the uncertainty of a physical quantity that is due to its quantum origin. In certain situations, quantum noise appears as shot noise; for example, most optical communications use amplitude modulation, and thus, the quantum noise appears as shot noise only.Trace metal: Trace metals are metals that can be present in animal and plant cells and tissue and are a necessary part of nutrition and physiology. Ingestion of, or exposure to, excessive quantities can be toxic.Atomic mass: right |thumb|200px|Stylized [[lithium-7 atom: 3 protons, 4 neutrons, & 3 electrons (total electrons are ~1/4300th of the mass of the nucleus). It has a mass of 7.Zinc toxicityIron stress repressed RNA: Iron stress repressed RNA (IsrR) is a cis-encoded antisense RNA which regulates the expression of the photosynthetic protein isiA. IsiA expression is activated by the Ferric uptake regulator protein (Fur) under iron stress conditions.Electrospray ionizationTandem mass spectrometry: 300 px|right|thumb|A [[Quadrupole mass analyzer|quadrupole time-of-flight hybrid tandem mass spectrometer.]]Powder diffraction: Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials.B.Gas chromatography–mass spectrometry: right|300 px|Example of a GC-MS instrument|thumbSoft laser desorption: Soft laser desorption is laser desorption of large molecules that results in ionization without fragmentation. "Soft" in the context of ion formation means forming ions without breaking chemical bonds.Phase problem: In physics the phase problem is the name given to the problem of loss of information concerning the phase that can occur when making a physical measurement. The name itself comes from the field of x-ray crystallography, where the phase problem has to be solved for the determination of a structure from diffraction data.