Rubidium atomic clock

Camparo, James. The Rubidium Atomic Clock and Basic Research. Physics Today (November 2007) 33 39. 

A block diagram of a typical rubidium atomic clock is... 

Rubidium is used to make atomic clocks. An atomic clock is a device for keeping very exact time. A radioactive isotope of rubidium is also used to measure the age of very old objects. In general, however, rubidium and its compounds have few practical uses. 

There are relatively few commercial uses for mbidium or its compounds. Rubidium is used to make atomic clocks. But these clocks are used only for very specialized purposes where very precise timekeeping is important. Rubidium is also used to make photocells. A photocell is a device for converting light energy into electrical energy. But other members of the alkali family are still preferred for this application. 

Chapter 4 examines the heavier alkali metals—rubidium, cesium, and francium. Francium is a radioactive, rare element its longest-lived isotope has a half-life of only 22 minutes. The relative abundances of rubidium and cesium are much less than the abundances of lithium, sodium, or potassium, yet rubidium and cesium find important applications in atomic clocks and laser technology. 

In this chapter the reader will learn about the syntheses of rubidium, cesium, and francium in stars, the chemistry of rubidium and cesium, the use of cesium in atomic clocks, and other applications of rubidium and cesium. Too little francium exists for it to have any practical uses. 

Scientific Clocks. Scientific and industrial purposes demand atomic clocks with fer more accuracy and stabihty than that of household clocks or watches. Atomic clocks make use of the fact that all atoms are capable of existing at a number of different discrete (noncontinuous) levels of energy. As an atom jumps back and forth between a higher and a lower energy level, it resonates at a particular frequency, and this frequency is exactly the same for every atom of a given element. Eor example, cesium-133 atoms (one of the two types of atoms most commonly used in atomic clocks rubidium is the other) resonate between two particular energy levels at 9,192,631,770 cycles per second. (In fact, the time it takes for this number of oscillations of a cesium-133 atom to take... 

When rubidium gas is placed in sealed glass cells along with an inert gas, it becomes a rubidium-gas cell clock. Because of the consistent and exact frequency (vibrations) of it atoms, it is a very accurate timekeeper. 

Searles E. Simon, Performance Characteristics of Portable Atomic Rubidium Clock and Frequency Standard , R DTR ECOM-3339 (1970) 8) ChemRubHdb (1978), B-44... 

---