Products Description of Cesium Iodide CAS#7789-17-5
Cesium iodide (CsI) and inorganic halide materials such as CsI(Tl) are widely utilized as scintillation media in high-energy particle detection and ionizing radiation detectors. Vacuum-deposited CsI(Tl) thin films were among the first scintillator materials applied in X-ray imaging through photoelectric conversion systems.
In advanced digital X-ray imaging technologies, CsI(Tl) scintillator films are extensively used due to their excellent X-ray scintillation efficiency, high spatial resolution, and strong compatibility with spectrally sensitive silicon-based readout arrays, enabling high-quality and accurate imaging performance.

Cesium iodide Chemical Properties
Melting point | 626 °C (lit.) |
Boiling point | 1280 °C |
density | 4.51 g/mL at 25 °C (lit.) |
refractive index | 1.7876 |
Fp | 1280°C |
storage temp. | Keep in dark place,Inert atmosphere,Room temperature |
solubility | soluble in ethanol, methanol, acetone |
form | beads |
Specific Gravity | 4.51 |
color | White |
PH | pH(50g/l, 25℃) : 5.0~9.0 |
Water Solubility | 74 g/100 mL (20 ºC) |
Sensitive | Hygroscopic |
Merck | 142014 |
Exposure limits | ACGIH: TWA 0.01 ppm |
Dielectric constant | 5.6(Ambient) |
Stability: | Stable. Deliquescent. |
CAS DataBase Reference | 7789-17-5(CAS DataBase Reference) |
NIST Chemistry Reference | Cesium iodide(7789-17-5) |
EPA Substance Registry System | Cesium iodide (CsI) (7789-17-5) |
Hazard Codes | Xn,Xi |
Risk Statements | 36/37/38-42/43-43 |
Safety Statements | 22-36/37-45 |
RIDADR | UN 3077 9 / PGIII |
WGK Germany | 2 |
RTECS | FL0350000 |
F | 8 |
TSCA | Yes |
HS Code | 28276000 |
Toxicity | LD50 i.p. in rats: 1.4 g/kg (Cochran) |

Product Application of Cesium Iodide CAS#7789-17-5
Cesium iodide crystals are widely used as scintillation materials in electromagnetic calorimeters for particle physics experiments. They are also applied as optical components in Fourier transform infrared (FT-IR) spectrometers, serving as spectroscope materials due to their excellent infrared transmission properties.
Compared with commonly used potassium bromide spectroscopes, cesium iodide offers a broader light transmission range, extending into the far-infrared region. However, cesium iodide optical crystals are relatively soft and exhibit no cleavage, making it challenging to achieve a flat and highly polished surface.
Furthermore, cesium iodide optical crystals need to be stored in dry environments to prevent reactions with moisture. Applying a germanium coating to the surface can effectively reduce the impact of atmospheric humidity during spectroscope handling and replacement.


