Solid state lasers, although a 50 year old technology, have remained relevant. However, because of the crystal laser medium there are many considerations specifically inherent to solid state lasers in contrast with gas lasers. In this paper I will discuss the theory of lasers, the basic structure of a solid state laser and contrast some of the solid state components.
The theory of lasers
The quantum theory of radiation (Einstein, 1917) established conditions in which we could predict the number of excited states of electrons in an atom that could spontaneously emit a photon versus the number of states expected to emit a photon by stimulation. Einstein’s theory predicted that in a state of population inversion, one where the number of stimulated electrons exceeds the number of ground state electrons, an overall energy gain was possible (Einstein A and B Coefficients). Bohr’s energy relation shows
E_2 - E_1 = 〖hν〗_21
where E_2 and E_2 are energies of the gap, h is Planck’s constant and 〖hν〗_21 is the frequency of the absorbed or emitted radiation. Atoms can only absorb photons of certain wavelengths corresponding to these frequencies carrying the amount of energy necessary to raise the state of the electron (Lamb, 1964). Interaction with the radiative electromagnetic field and the dipole of the ion is the action elevating the energy level of the electron. After time, the electron will return to its previous state spontaneously and emit a photon of equal energy. However, if an electron in a stimulated state absorbs a second photon, that energy will push the electron down to its original state and two photons are emitted. Stimulated emission is indistinguishable from the radiation field stimulating the atoms. Hence, the radia...
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Oppenheimer's early studies were devoted mainly to energy processes of subatomic particles, including electrons,positrons, and cosmic rays. He also did innovative work on not only neutron stars but also black holes. His university provided him with an excellent opportunity to research the quantum theory, along with exploration and development of its full significance. This helped him train an entire generation of U.S. physicists. Furthermore, the most important impact was the invention of the atomic bomb.
The amazing transformation the study of physics underwent in the two decades following the turn of the 20th century is a well-known story. Physicists, on the verge of declaring the physical world “understood”, discovered that existing theories failed to describe the behavior of the atom. In a very short time, a more fundamental theory of the ...
Niels Bohr's model of the hydrogen atom, was the primary reason for the understanding of energy levels.Bohr was able to explain the bright line spectrum of hydrogen. Sparked by the recent discovery of the diffraction patterns, scientists believed electrons could be described as waves. Bohr hypothesized that energy is being added to the hydrogen gas in the electricity form, and then leaving the gas in the form of light. He figured the light rays to be quantized, meaning only certain frequencies of the light rays can be seen. In turn, he reasoned that the hydrogen atoms themselves were quantized and, that they only can exist in certain energy levels. When the atoms absorb specific amounts of energy, they exist for a small period of time in higher energy levels. But as soon as these atoms lose their energy, they move back down to the lower levels of energy. His theory went on to state how the hydrogen atom can move up and down the energy levels, one level at a time, and can never stop in between. Every hydrogen atom is made up of a single electron - proton system. Because the negative electron is attracted to the positive proton, potential energy is created inside the atom.He figured that the farther away the electron is from the proton, the greater the potential energy is inside. In conclusion, since hydrogen atoms emit light energy in specific frequencies, the hydrogen atom must be within a specific energy level and nothing else. The different wavelengths help to determine the different colors emitted from the atom. The greater the wavelength, the faster the atom can be filled and jump to a higher level.Bohr developed his theory after studying the work of Einstein's ideas on the photons of energy.
In basic research, special model systems are needed for quantitative investigations of the relevant and fundamental processes in thin film materials science. In particular, these model systems enable the investigation of i.e. nucleation and growth processes, solid state reactions, the thermal and mechanical stability of thin film systems and phase boundaries. Results of combined experimental and theoretical investigations are a prerequisite for the development of new thin film systems and tailoring of their microstructure and performance.
The author tells of how waves are effected by quantum mechanic. He also discusses the fact that electromagnetic radiation, or photons, are actually particles and waves. He continues to discuss how matter particles are also matter, but because of their h bar, is so small, the effects are not seen. Green concludes the quantum mechanics discussion by talking about the uncertainty principle.Chapter 5: The need for a New Theory: General Relativity vs.
The molar specific heats of most solids at room temperature and above are nearly constant, in agreement with the Law of Dulong and Petit. At lower temperatures the specific heats drop as quantum processes become significant. The Einstein-Debye model of specific heat describes the low temperature behavior.
Beta radiation/emission – Beta particles are electrons (0-1e) that have been released from the nucleus of a radioactive atom when a neutron decays into a proton and electron. Beta decay/emission happens when the neutron to proton ratio is too high due to excess neutrons. 10n 11p + 0-1e (mass is still conserved as well as number of protons.)
... middle of paper ... ... 14 Nov 2011.. http://web.ebscohost.com/lrc/detail?vid=4&hid=110&sid=fef50b1c-4aba-40fd-83b1- 583a32991f55@sessionmgr110&bdata=JnNpdGU9bHJjLWxpdmU=> Edrich, Matthias. The.
Quantum thermodynamic scientists are aiming to explore the behavior outside the lines of conventional thermodynamics. This exploration could be used for functional cases, which include “improving lab-based refrigeration techniques, creating batteries with enhanced capabilities and refining technology of quantum computing.” (Merali P.1). However, this field is still in an early state of exploration. Experiments, including the one that is being performed at Oxford University, are just beginning to test these predictions. “A flurry of attempts has been made to calculate how thermodynamics and the quantum theory might combine” (Merali P. 1). However, quantum physicist Peter Hänggi stated that “there is far too much theory and not enough experiment” (Merali P.1) in this field of study, which is why its credibility is undermined. Nevertheless, people are starting to put more effort into understanding quantum thermodynamics in order to make
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states strikes an excited atom, the atom is stimulated, as it falls back to a
Radioactivity is the energy or particles that are released from the nucleus of an atom due to spontaneous changes. Some atoms are unstable, and emitting radiation will achieve a stable state. The main forms of radiation emissions from a decaying and unstable nucleus can be in the form of alpha, beta or gamma radiation. When a positively-charged particle is emitted from the nucleus of an atom, this is called alpha decay. This alpha particle would consist of two protons and two neutrons, similar to a helium-4 nucleus. Whereas when a particle, either as an electron with either negative or positive charge, is emitted from the nucleus, this would be known as beta decay. And finally, when a nucleus is at a high energy state, photons known as gamma particles would be released to lower the energy state. Worldwide, people have found the use of radioactivity for society, from scientific applications to medical uses and to industrial uses. However, there are many positive and negative effects of using radioactivity.