- Cesium atomic clocks employ a beam of cesium atoms. The clock separates cesium atoms of different energy levels by magnetic field.
- Hydrogen atomic clocks maintain hydrogen atoms at the required energy level in a container with walls of a special material so that the atoms don’t lose their higher energy state too quickly.
- Rubidium atomic clocks, the simplest and most compact of all, use a glass cell of rubidium gas that changes its absorption of light at the optical rubidium frequency when the surrounding microwave frequency is just right.
Atomic Clocks – Why in News?
Three atomic clocks onboard one of the satellites of the Indian Regional Navigation Satellite System (IRNSS) have failed.
The three atomic clocks used onboard each satellite of the IRNSS are used for precise coordination and to well-account for the effects of general relativity.
With the failure of all three clocks – one primary and two backups
Atomic Clocks – Rubidium
Rubidium atomic clocks, though less accurate at measuring the passage of time than are hydrogen maser clocks, are still quite accurate, relatively cheap and widely used. They neither gain nor lose a second in tens of millions of years.
They measure time according to the frequency of microwave emissions by electrons in a cooled rubidium atom, called the rubidium standard.
When the atoms are of the element caesium instead, the resulting clock is also referred to as a primary frequency standard given its use in defining the standard times of many countries. Our own Indian Standard Time is ‘kept’ by caesium atomic clocks in Delhi’s National Physical Laboratory.
Cesium is a rare, silver-white, shiny metal with brilliant blue spectral lines; the element’s name comes from “caesius,” a Latin word meaning “sky blue.” It is the softest metal, with a consistency of wax at room temperature. It would melt in your hands — if it didn’t explode first, as it is highly reactive to moisture
The most accurate atomic clocks available today use the cesium atom and the normal magnetic fields and detectors. In addition, the cesium atoms are stopped from zipping back and forth by laser beams, reducing small changes in frequency due to the Doppler effect.
Cesium is incredibly accurate at timekeeping and is used in atomic clocks. The official definition of a second is the time it takes for the cesium atom to vibrate 9,192,631,770 times between energy levels. Cesium-based atomic clocks lose one second per 100 million years
Cesium is one of four metals that are liquid at or near room temperature; the others are mercury (melting point of minus 37.9 F, or minus 38.8 C), gallium (melting point of 85.6 F, or 29.8 C) and francium (melting point of 80.6 F, or 27 C)