Caesium peroxide or cesium peroxide is a compound of

caesium Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elemental metals that a ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

. It can be formed from caesium metal by adding a stoichiometric amount in

ammonia solution Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Although ...

, or oxidizing the solid metal directly. :2Cs + O₂ → Cs₂O₂ It can also be formed by the thermal decomposition of

caesium superoxide Caesium superoxide is the superoxide of caesium. It is an orange solid. Preparation Burning caesium in excess oxygen will produce caesium superoxide. : Properties Caesium superoxide's crystal structure is same as calcium carbide. It contains ...

: :2CsO₂ → Cs₂O₂ + O₂ Upon heating until 650°C, the compound will decompose to

caesium monoxide Caesium monoxide, (Cs2O), often simply Caesium oxide, is the simplest and most common oxide of the caesium. It forms yellow-orange hexagonal crystals. Uses Caesium oxide is used in photocathodes to detect infrared signals in devices such as image ...

and

atomic oxygen There are several known allotropes of oxygen. The most familiar is molecular oxygen (O2), present at significant levels in Earth's atmosphere and also known as dioxygen or triplet oxygen. Another is the highly reactive ozone (O3). Others are: *A ...

: :

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Caesium peroxide shows a Raman vibration at 743 cm⁻¹, due to the presence of the

peroxide In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen p ...

ions. The compound is often used as a coating for

photocathode A photocathode is a surface engineered to convert light (photons) into electrons using the photoelectric effect. Photocathodes are important in accelerator physics where they are utilised in a photoinjector to generate high brightness electron be ...

s, due to its low

work function In solid-state physics, the work function (sometimes spelt workfunction) is the minimum thermodynamic work (i.e., energy) needed to remove an electron from a solid to a point in the vacuum immediately outside the solid surface. Here "immediately" m ...

References

Peroxides Caesium compounds {{inorganic-compound-stub