infrared radiation

infrared radiation
Name	Infrared radiation
Wavelength	700 nm–1 mm
Frequency	430 THz–300 GHz
Discovery	1800
Discoverer	William Herschel

infrared radiation Infrared radiation is electromagnetic energy with wavelengths longer than visible red light and shorter than microwave radiation. It plays a central role in astrophysics, climatology, and remote sensing, and underpins technologies developed by organizations such as NASA, European Space Agency, and National Institute of Standards and Technology. Measurements of infrared emission inform missions like James Webb Space Telescope, Spitzer Space Telescope, and instruments aboard Hubble Space Telescope.

Definition and Properties

Infrared radiation denotes electromagnetic waves with wavelengths roughly between 700 nanometres and 1 millimetre, corresponding to frequencies from about 430 terahertz to 300 gigahertz, and photon energies used in experiments at institutions like Max Planck Institute for Astronomy, Lawrence Berkeley National Laboratory, and Rutherford Appleton Laboratory. Key physical properties include blackbody emission described by Planck's law, energy distribution governed by Stefan–Boltzmann law, and quantization into photons as established in works linked to Albert Einstein and Max Planck. Polarization, coherence, and propagation through media are analyzed in studies at MIT, Stanford University, and Caltech laboratories.

Classification and Spectrum

The infrared band is commonly subdivided into near-infrared, mid-infrared, and far-infrared regions used by groups like International Astronomical Union and International Organization for Standardization. Near-infrared overlaps with wavelengths used in fiber communications developed by companies such as Corning Incorporated and standards bodies like ITU. Mid-infrared encompasses vibrational spectroscopy ranges exploited by researchers at Scripps Research, Lawrence Livermore National Laboratory, and Argonne National Laboratory, while far-infrared connects to submillimetre astronomy pursued by facilities like Atacama Large Millimeter Array and Herschel Space Observatory.

Sources and Detection

Natural sources include stellar objects observed by teams from European Southern Observatory, Harvard–Smithsonian Center for Astrophysics, and Carnegie Institution for Science, planetary atmospheres studied by Jet Propulsion Laboratory missions, and terrestrial emission central to research at National Center for Atmospheric Research. Artificial sources range from incandescent emitters used in General Electric products to semiconductor lasers advanced by corporations like Intel and Osram. Detection technologies include photodiodes and bolometers produced by suppliers such as Teledyne Technologies, cooled detectors using cryogenics developed at CERN, and focal plane arrays implemented in instruments aboard NOAA satellites.

Interaction with Matter

Interactions include absorption by molecular vibrational modes investigated by chemists at Royal Society of Chemistry institutions, scattering processes modeled using theories from James Clerk Maxwell and employed in experiments at Imperial College London, and emission dependent on temperature studied by researchers at Niels Bohr Institute and Princeton University. Materials such as silicon and germanium, characterized in publications from IEEE, are widely used for optics and sensors; coatings and metamaterials researched at Bell Labs and California Institute of Technology tailor emissivity and reflectance across infrared bands.

Applications and Technologies

Infrared techniques enable thermal imaging systems produced by firms like FLIR Systems for use in search and rescue, building inspection, and law enforcement associated with agencies such as FBI and Department of Homeland Security. Spectroscopic methods underpin chemical analysis in pharmaceutical companies like Pfizer and environmental monitoring by organizations like Environmental Protection Agency. Astronomy leverages infrared instruments on facilities including Keck Observatory and Subaru Telescope to study star formation and exoplanets; telecommunications employ near-infrared lasers in fiber networks standardized by IEEE 802.3. Military and aerospace programs at Lockheed Martin and Northrop Grumman develop infrared seekers and countermeasures, while medical devices created by Medtronic and research at Mayo Clinic explore therapeutic infrared applications.

Health and Safety

Exposure guidelines are set by regulatory bodies such as Occupational Safety and Health Administration and World Health Organization, with standards for workplace limits informed by studies at National Institutes of Health and American National Standards Institute. High-intensity infrared can cause thermal burns or retinal injury investigated in clinical centers like Johns Hopkins Medicine and Cleveland Clinic, and safety protocols for industrial lasers are enforced by authorities including Food and Drug Administration. Protective equipment and engineering controls are developed by manufacturers and tested in laboratories affiliated with Underwriters Laboratories.

History and Research Developments

Discovery and early studies trace to astronomer William Herschel, while theoretical foundations were advanced by physicists such as Max Planck, Ludwig Boltzmann, and Lord Rayleigh. Twentieth-century progress involved instrumental innovations at Bell Telephone Laboratories, observational breakthroughs enabled by Palomar Observatory, and space-based infrared astronomy led by missions from NASA and European Space Agency. Current research directions at institutes like Caltech, University of Cambridge, and ETH Zurich include metamaterial emitters, quantum cascade lasers, and cryogenic detector arrays, with interdisciplinary collaborations involving National Science Foundation grants and industrial partnerships spanning firms like Honeywell and Raytheon Technologies.

Category:Electromagnetic spectrum