What is meant by metastable state give an example?
A ball resting in a hollow on a slope is a simple example of metastability. If the ball is only slightly pushed, it will settle back into its hollow, but a stronger push may start the ball rolling down the slope. Bowling pins show similar metastability by either merely wobbling for a moment or tipping over completely.
What is the role of metastable state?
In a three-level laser, the material is first excited to a short-lived high-energy state that spontaneously drops to a somewhat lower-energy state with an unusually long lifetime, called a metastable state. The metastable state is important because it traps and holds the excitation energy, building up a…
What is metastable state in phase rule?
Thus, the state of relatively stable or metastable equilibrium is defined as the state in which a system remains for a long period of time, and any slight disturbance causing the system to deviate from the metastable state does not result in the system passing into another state.
What is metastable state of water?
Metastable States This supercool water can stay liquid, but not for a long time, and it then freezes abruptly. Such states are called metastable. They are not equilibrium states; at negative temperatures the only equilibrium state of water is ice.
What is meant by optical pumping?
optical pumping, in physics, the use of light energy to raise the atoms of a system from one energy level to another. A system may consist of atoms having a random orientation of their individual magnetic fields.
How is metastable state created?
In some of these lasers, helium atoms are excited into metastable states by an electric discharge. In collisions with other atoms (e.g. neon in a helium–neon laser), they can then transfer the excitation energy to those atoms. It also occurs that after the laser transition atoms are “stuck” in a metastable state.
What is Fullform of laser?
Light amplification by stimulated emission of radiation
Laser/Full name
What is population inversion physics?
population inversion, in physics, the redistribution of atomic energy levels that takes place in a system so that laser action can occur. Normally, a system of atoms is in temperature equilibrium and there are always more atoms in low energy states than in higher ones.
What does the metastable state actually represent?
Metastable state, in physics, is the particularlyly excited energy level or higher energy level of an atom, nucleus, or other systems that have a longer lifetime than the ordinary excited states (or the energy levels) and that generally has a shorter lifetime than the lowest, often highly stable, energy state is known as the ground state.
What is the role of metastable state in laser?
Metastable State in Lasers Metastable states also play some important and key roles in gas lasers: In a number of gas lasers, helium atoms are excited into metastable states by an electrical discharge. During collisions with other atoms (e.g. neon in a helium-neon laser), they can then transfer or exchange the excitation energy to those atoms.
What is the definition of metastable state in laser?
Metastable States Metastable States of Solid-state Gain Media. Solid-state gain media usually have a metastable electronic state as upper laser level, and often some additional metastable states (energy levels). Trapping of Laser-active Atoms or Ions in Metastable States. Metastable States in Gas Lasers. Lasers Without Metastable States.