What was the phosphor Roentgen used in early experiments with x-rays?

What was the phosphor Roentgen used in early experiments with x-rays?

• A. Calcium tungstate
• B. Cadmium tungstate
• C. Molybdenum sulfide
• D. Barium platinocyanide

Answer: (D)

Roentgen needed a screen that would glow when hit by X-rays so he could visualize the radiographic image without complex cameras. He used a fluorescent phosphor called barium platinocyanide, which emits visible light upon X-ray exposure, making the shadows cast by objects (like a hand) visible on the screen. The other materials—calcium tungstate and cadmium tungstate—became common phosphors later for X-ray imaging, used in intensified screens, while molybdenum sulfide isn’t a standard X-ray phosphor. This is why barium platinocyanide is the correct choice.

Roentgen needed a screen that would glow when hit by X-rays so he could visualize the radiographic image without complex cameras. He used a fluorescent phosphor called barium platinocyanide, which emits visible light upon X-ray exposure, making the shadows cast by objects (like a hand) visible on the screen. The other materials—calcium tungstate and cadmium tungstate—became common phosphors later for X-ray imaging, used in intensified screens, while molybdenum sulfide isn’t a standard X-ray phosphor. This is why barium platinocyanide is the correct choice.