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In atomic physics and quantum chemistry, the Aufbau principle (/ ˈ aʊ f b aʊ /, from German: Aufbauprinzip, lit. ' building-up principle '), also called the Aufbau rule , states that in the ground state of an atom or ion , electrons first fill subshells of the lowest available energy , then fill subshells of higher energy.
Hydrogen fluoride laser: 2.7 to 2.9 μm for hydrogen fluoride (<80% atmospheric transmittance) Chemical reaction in a burning jet of ethylene and nitrogen trifluoride (NF 3) Used in research for laser weaponry, operated in continuous-wave mode, can have power in the megawatt range. Deuterium fluoride laser
As an approximate rule, electron configurations are given by the Aufbau principle and the Madelung rule. However there are numerous exceptions; for example the lightest exception is chromium, which would be predicted to have the configuration 1s 2 2s 2 2p 6 3s 2 3p 6 3d 4 4s 2 , written as [Ar] 3d 4 4s 2 , but whose actual configuration given ...
This doubly charged ion has been made by accelerating the helium hydride ion to 900 keV, and firing it into argon. It only has a short life of 4 ns. [70] H 2 He + has been made and could occur in nature via H 2 + He + → H 2 He +. [70] H 3 He + n exists for n from 1 to over 30, and there are also clusters with more hydrogen atoms and helium. [73]
The active laser medium (also called a gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source .
The first gas laser, the Helium–neon laser (HeNe), was co-invented by Iranian engineer and scientist Ali Javan and American physicist William R. Bennett, Jr., in 1960. It produced a coherent light beam in the infrared region of the spectrum at 1.15 micrometres. [1] A helium-neon laser is a well-known type of gas laser
The explosively pumped gas dynamic laser is a version of GDL pumped by expansion of explosion products. Hexanitrobenzene and/or tetranitromethane with metal powder is the preferred explosive. This device could have very high pulsed peak power output suitable for laser weapons .
The gain medium of the laser, as suggested by its name, is a mixture of helium and neon gases, in approximately a 10:1 ratio, contained at low pressure in a glass envelope. The gas mixture is mostly helium, so that helium atoms can be excited. The excited helium atoms collide with neon atoms, exciting some of them to the state that radiates 632 ...