Emissionsspektra

Emissionsspektra are the spectra produced when a source emits electromagnetic radiation as a function of wavelength or frequency. They characterize the wavelengths at which a source releases photons and the relative intensities of those wavelengths.

The emission spectrum can be classified as atomic (line spectrum), molecular (bands), or continuous. Atomic emission spectra arise from electronic transitions between discrete energy levels in atoms or ions, yielding sharp lines at characteristic wavelengths. Molecular emission spectra arise from transitions in molecules and often present vibrational-rotational band structures. Continuous emission occurs when a hot, dense source emits across a broad range of wavelengths, as in a filament or the sun's photosphere.

Origin and information: The emission of a photon occurs when a system in an excited state relaxes to a lower energy level; the energy difference determines the photon wavelength. The pattern of lines or bands serves as a fingerprint for the elements or compounds present. Population of excited states depends on temperature and density, influencing line intensities.

Applications: Emission spectra are central in spectroscopy for material identification, chemical analysis, and diagnostic of plasmas. In astronomy, emission spectra from nebulae and stars reveal composition, temperature, density, and motion through redshifts or Doppler broadening. In industry, flame tests and spark discharge analysis use emission spectra to detect elements.

Measurement: Emission spectra are obtained with spectrometers or spectrographs that disperse light via prisms or diffraction gratings and detect it with photodetectors or cameras. Instrumental resolution, calibration, and background subtraction affect accuracy. Emission spectra complement absorption spectra in revealing the interaction of light with matter.