Caesium hydride is a compound of caesium

Caesium

Caesium or cesium is the chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C , which makes it one of only five elemental metals that are liquid at room temperature...

 and hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

.
It was the first substance to be created by light-induced particle formation in metal vapor, and showed promise in early studies of an ion propulsion system using caesium.

The caesium nuclei in CsH can be hyperpolarized through interactions with an optically pumped

Optical pumping

Optical pumping is a process in which light is used to raise electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction, to pump the active laser medium so as to achieve population inversion...

 caesium vapor in a process known as spin-exchange optical pumping (SEOP). SEOP can increase the nuclear magnetic resonance

Nuclear magnetic resonance

Nuclear magnetic resonance is a physical phenomenon in which magnetic nuclei in a magnetic field absorb and re-emit electromagnetic radiation...

 (NMR) signal of caesium nuclei by an order of magnitude.

Crystal structure

At room temperature and atmospheric pressure, CsH has the same structure as NaCl.