Examples of emission in the following topics:
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- The emission spectrum of atomic hydrogen is divided into a number of spectral series.
- The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted by an atom's electrons when they are returned to a lower energy state.
- Each element's emission spectrum is unique, and therefore spectroscopy can be used to identify elements present in matter of unknown composition.
- Similarly, the emission spectra of molecules can be used in chemical analysis of substances.
- Explain how the lines in the emission spectrum of hydrogen are related to electron energy levels.
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- Collisions with other atoms or molecules can absorb the excitation energy and prevent emission.
- Oxygen emissions are green or brownish-red, depending on the amount of energy absorbed.
- Nitrogen emissions are blue if the atom regains an electron after it has been ionized and red if the atom returns to ground state from an excited state.
- Collisions become more frequent farther down in the atmosphere, and red emissions do not have time to happen; eventually, even green light emissions are prevented.
- This is why there is a color differential with altitude: at high altitudes, oxygen's red emissions remain; then, oxygen's green emissions and nitrogen's blue and red emissions; and finally, only nitrogen's blue and red emissions are left, because collisions prevent oxygen from emitting any light at all.
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- They indicated that during the 21st century, the global surface temperature is likely to rise another 1.1 to 2.9 °C (2 to 5.2 °F) for their lowest emissions scenario, and 2.4 to 6.4 °C (4.3 to 11.5 °F) for their highest.
- Proposed policy responses to global warming include mitigation by emissions reduction, adaptation to its effects, and possible future geoengineering.
- Parties to the UNFCCC have adopted a range of policies designed to reduce greenhouse gas emissions and to assist in adaptation to global warming.
- This group has agreed that deep cuts in emissions are required, and that future global warming should be limited to below 2.0 °C (3.6 °F) relative to the pre-industrial level.
- Reports published in 2011 by the United Nations Environment Programme and the International Energy Agency suggest that efforts as of the early 21st century to reduce emissions may be inadequate to meet the UNFCCC's 2.0 °C target.
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- Global warming and climate change are generally accepted as being caused by anthropogenic (man-made) greenhouse gas emissions.
- The majority of greenhouse gas emissions are due to burning fossil fuels, while some is due to deforestation.
- According to this study, hydroelectricity produces the lowest CO2 emissions, wind produces the second lowest CO2 emissions, nuclear energy produces the third lowest, and solar photovoltaic produces the fourth lowest.
- The cost of electricity production from gas would increase by 30% if external costs such as damage to the environment and to human health, from the airborne particulate matter, nitrogen oxides, chromium VI, and arsenic emissions produced by these sources, were taken into account.
- Total carbon emissions has risen exponentially since the industrial revolution, from approximately 1 billion metric tons pre-1900 to 10 billion metric tons now.
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- Although it challenged the knowledge of classical physics, the model's success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen.
- In terms of electron emission, this would represent a continuum of frequencies being emitted since, as the electron moved closer to the nucleus, it would move faster and would emit a different frequency than those experimentally observed.
- The Bohr theory solved this problem and correctly explained the experimentally obtained Rydberg formula for emission lines.
- For sufficiently large values of n (so-called Rydberg states), the two orbits involved in the emission process have nearly the same rotation frequency so that the classical orbital frequency is not ambiguous.
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- Air pollutants are considered primary when the harmful particles are directly emitted into the atmosphere; secondary pollutants are products of reactions that occur following emission.
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- It decays through neutron emission with a half-life of 1.39 ×10−22 seconds.
- It decays through double neutron emission and has a half-life of at least 9.1 × 10−22 seconds.
- 6H decays through triple neutron emission and has a half-life of 2.90×10−22 seconds.
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- Typically, one photon is either energetic enough to cause emission of an electron or the energy is lost as the atom returns back to the ground state.
- The time lag between the incidence of radiation and the emission of a photoelectron is very small, less than 10−9 second, and is unaffected by intensity changes.
- By means of a series of electrodes (dynodes) at ever-higher potentials, these electrons are accelerated and substantially increased in number through secondary emission to provide a readily detectable output current.
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- It is the relaxation of these electrons from the excited state back to the ground state that produces the glow that is visible around the space shuttle (see the concept about the emission spectra for more information).
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- Human activities have increased greenhouse gas concentrations n the atmosphere through the combustion of fossil fuels, release of methane from farms, industrial emissions, and deforestation.