Excitations

In physics and related fields, 'excitations' refer to the processes where a system, such as an atom, molecule, or material, absorbs energy and transitions to a higher energy state than its ground state. This absorbed energy can manifest as increased internal energy, altered motion, or the release of particles like photons. The specific nature of excitation depends on the system and the type of energy involved (e.g., photons, electrons, or heat). excitations are fundamental to understanding a wide range of phenomena, including atomic spectra, luminescence, and the behavior of semiconductors and lasers. The energy difference between the initial and excited states dictates the nature of the emitted radiation. excitations drive changes in electronic structure, vibrational modes, and rotational levels within a system.

Excitations meaning with examples

• In a fluorescent light bulb, the electrical current excites mercury atoms, causing them to emit ultraviolet photons. These UV photons then excite the phosphor coating on the bulb's interior, leading to the emission of visible light. The efficiency of the bulb is directly related to how well the excitation process converts electrical energy into usable light output. The emitted light's spectrum depends on the phosphor's excitation and emission characteristics.
• When a laser beam interacts with a material, it can excite the material's atoms or molecules. This excitation leads to the material's absorption of energy, followed by the emission of light, which can have various practical uses, such as cutting and welding materials or in data storage. The nature of excitation can depend on the wavelength of the laser, which can be used to selectively target different material excitation.
• The process of 'photoluminescence' involves excitation of a material through absorption of photons, leading to emission of other photons at a different wavelength. This phenomenon is common in fluorescent dyes and quantum dots and utilized in applications such as bioimaging and displays. The time delay between excitation and emission reveals important information about the excited state of the material.
• In semiconductors, 'excitations' play a vital role in device operation. When an electron absorbs energy (e.g., from a voltage or light), it can be excited to a higher energy level, leaving behind a 'hole'. These excited electrons and holes can move, leading to the flow of current and performing desired functions. The properties of semiconductor devices are engineered to manage and exploit these excitations effectively.