A recommendation letter or letter of recommendation, also known as a letter of reference, reference letter or simply reference, is a document in which the writer assesses the qualities, characteristics, and capabilities of the person being recommended in terms of that individual's ability to perform a particular task or function.
This article is about stable isotope ratios. For the general category of stable nuclides, see Stable nuclide. The term stable isotope has a similar meaning to stable nuclide, but is preferably used when speaking of nuclides of a specific element.his article is about stable isotope ratios. For the general category of stable nuclides, see Stable nuclide. The term stable isotope has a similar meaning to stable nuclide, but is preferably used when speaking of nuclides of a specific element.
When an unstable nucleus of a radioactive isotope spontaneously  decays, the radioactive decay process is normally gamma radiation,  beta particle or alpha particle emission â¦ .his is called Carbon12.   Carbon14 with 6 protons and 8 neutrons, is unstable and decays by releasing a beta particle from its nucleus to become a stable isotope, Nitrogen14. which has 7 protons and 7 neutrons. That refers to an isotope that is unstable-the atoms will decay after a while.