In an "indirect" gap, a photon cannot be emitted because the electron must pass through an intermediate state and transfer momentum to the crystal lattice.
...photons cannot carry crystal momentum,...in an indirect band gap material, the process must also involve the absorption or emission of a phonon, where the phonon momentum equals the difference between the electron and hole momentum.
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The momentum of an electron refers to its mass in motion, which is determined by its velocity and mass. It is a fundamental property of an electron and plays a significant role in understanding its behavior.
The momentum of an electron can be calculated using the equation p = mv, where p is the momentum, m is the mass of the electron, and v is its velocity. This equation is derived from Newton's second law of motion.
The unit of measurement for electron momentum is kilogram-meter per second (kg•m/s) in the SI system. In other systems, it may also be expressed as gram-centimeter per second (g•cm/s) or atomic unit of momentum (a.u.).
The momentum of an electron determines how it interacts with other particles and how it moves through a medium. A higher momentum means a faster-moving electron with greater kinetic energy, which can result in stronger interactions and a longer distance traveled before losing energy.
Yes, the momentum of an electron can be changed by altering its velocity or mass. This can be achieved through various means such as applying a force, changing the electron's energy level, or colliding with other particles.