Sapienza University of Rome
The Sapienza University of Rome called Sapienza or the University of Rome, is a collegiate research university located in Rome, Italy. Formally known as Università degli Studi di Roma "La Sapienza", it is one of the largest European universities by enrollments and one of the oldest in history, founded in 1303; the University is one of the most prestigious Italian universities ranking first in national rankings and in Southern Europe. Most of the Italian ruling class studied at Sapienza. Sapienza educated numerous notable alumni, including many Nobel laureates, Presidents of the European Parliament and European Commissioners, heads of several nations, notable religious figures and astronauts.. In September 2018, it was included in the top 100 of the QS World University Rankings Graduate Employability Ranking. Sapienza University of Rome was founded in 1303 with the Papal bull In Supremae praeminentia Dignitatis, issued on 20 April 1303 by Pope Boniface VIII, as a Studium for ecclesiastical studies more under his control than the universities of Bologna and Padua, making it the first pontifical university.
In 1431 Pope Eugene IV reorganized the studium with the bull In supremae, in which he granted masters and students alike the broadest possible privileges and decreed that the university should include the four schools of Law, Medicine and Theology. He introduced a new tax on wine. However, the University's days of splendour came to an end during the sack of Rome in 1527, when the studium was closed and the professors dispersed, some were killed. Pope Paul III restored the university shortly after his ascension to the pontificate in 1534. In the 1650s the university became meaning wisdom, a title it retains. In 1703, Pope Clement XI purchased some land with his private funds on the Janiculum, where he made a botanical garden, which soon became the most celebrated in Europe through the labours of the Trionfetti brothers; the first complete history of the Sapienza University was written in 1803-1806 by Filippo Maria Renazzi. University students were newly animated during the 19th-century Italian revival.
In 1870, La Sapienza stopped being the papal university and became the university of the capital of Italy. In 1935 the new university campus, planned by Marcello Piacentini, was completed. Sapienza University has many campuses in Rome but its main campus is the Città Universitaria, which covers 44 ha near the Roma Tiburtina Station; the university has satellite campuses outside Rome, the main of, in Latina. In 2011 a project was launched to build a campus with residence halls near Pietralata station, in collaboration with the Lazio region. In order to cope with the ever-increasing number of applicants, the Rector approved a new plan to expand the Città Universitaria, reallocate offices and enlarge faculties, as well as create new campuses for hosting local and foreign students; the Alessandrina University Library, built in 1667 by Pope Alexander VII, is the main library housing 1.5 million volumes. Orto Botanico dell'Università di Roma "La Sapienza", a botanical garden Sant'Ivo alla Sapienza San Pietro in Vincoli: the cloister is part of the Engineering School Villa Mirafiori: a Neo-Renaissance palace built during the 19th century, some rooms are decorated with fine frescoes.
The Department of Philosophy is located in this building. Since the 2011 reform, Sapienza University of Rome has 65 departments. Today Sapienza, with 140,000 students and 8,000 among academic and technical and administrative staff, is the largest university in Italy; the university has significant research programmes in the fields of engineering, natural sciences, biomedical sciences and humanities. It offers 10 Masters Programmes taught in English; as of the 2016 Academic Ranking of World Universities, Sapienza is positioned within the 151-200 group of universities and among the top 3% of universities in the world. In 2018, the subject Classics and Ancient history of Sapienza is ranked the 1st in the world by QS World University Rankings by subject; as the same ranking, the subject Archaeology ranks the 9th. In 2016, the Center for World University Rankings ranked the Sapienza University of Rome as the 90th in the world and the top in Italy in its World University Rankings. In order to cope with the large demand for admission to the university courses, some faculties hold a series of entrance examinations.
The entrance test decides which candidates will have access to the undergraduate course. For some faculties, the entrance test is only a mean through which the administration acknowledges the students' level of preparation. Students that do not pass the test can still enroll in their chosen degree courses but have to pass an additional exam during their first year. On 15 January 2008 the Vatican cancelled a planned visit to La Sapienza University by Pope Benedict XVI, to speak at the university ceremony launching the 2008 academic year due to protests by some students and professors; the title of the speech would have been'The Truth Makes Us Good and Goodness is Truth'. Some students and professors protested in reaction to a 1990 speech that Pope Benedict XVI gave in which he, in their opinion, endorsed the actions of the church against Galileo in 1633. Among the prominent scholars who have taught at the Sapienza University of Rome are architects Ernesto Basile and Bruno Zevi.
Edoardo Amaldi was an Italian physicist. Amaldi was born in Carpaneto Piacentino, the son of Ugo Amaldi, professor of mathematics at the University of Padua, Luisa Basini. Amaldi graduated under the supervision of Enrico Fermi and was his main collaborator until 1938, when Fermi left Italy for the United States. In 1939, Amaldi was drafted into the Royal Italian Army and returned to physics in 1941. After WWII, Amaldi held the chair of "General Physics" at the Sapienza University of Rome, rebuilt the post-Fermi school of physics, was the co-founder of the Italian National Institute for Nuclear Physics and of ESRO, he was the general secretary of CERN at its early stages when operations were still provisional, before September's 1954 official foundation. He pioneered in Europe the search for gravitational waves, his main scientific results were on slow neutrons in the Fermi group, the evidence for antiproton annihilations with emulsion techniques, somewhat contemporary to its production in accelerators by Emilio Segrè and collaborators.
Amaldi co-authored about 200 scientific publications ranging from atomic spectroscopy and nuclear physics to elementary particle physics and experimental gravitation, as well as textbooks for secondary schools and universities. He wrote historical-scientific books, like for example, the biography of his missing friend Ettore Majorana, he was elected a Foreign Honorary Member of the Soviet Academy of Sciences in 1958 and American Academy of Arts and Sciences in 1962. In 1963 he became foreign member of the Royal Netherlands Academy of Sciences. On 25 April 1968, he was elected as a Foreign Member of the Royal Society. Amaldi died unexpectedly on 5 December 1989, still in full activity, while he was president of the Accademia dei Lincei, of which he had been a member since 1948; the third Automated Transfer Vehicle of the European Space Agency bears his name. Via Panisperna boys I ragazzi di via Panisperna Oral History interview transcript with Edoardo Amaldi 8 April 1963, American Institute of Physics, Niels Bohr Library and Archives Oral History interview transcript with Edoardo Amaldi 9, 10 April 1969, American Institute of Physics, Niels Bohr Library and Archives Oral History interview transcript with Edoardo Amaldi 10 December 1982, American Institute of Physics, Niels Bohr Library and Archives Annotated bibliography for Edoardo Amaldi from the Alsos Digital Library for Nuclear Issues Amaldi's profile on INSPIRE-HEP
Quebec City Québec, is the capital city of the Canadian province of Quebec. The city had a population estimate of 531,902 in July 2016, the metropolitan area had a population of 800,296 in July 2016, making it the second largest city in Quebec after Montreal, the seventh largest metropolitan area and eleventh largest city in the country; the Algonquian people had named the area Kébec, an Algonquin word meaning "where the river narrows", because the Saint Lawrence River narrows proximate to the promontory of Quebec and its Cape Diamant. Explorer Samuel de Champlain founded a French settlement here in 1608, adopted the Algonquin name. Quebec City is one of the oldest European cities in North America; the ramparts surrounding Old Quebec are the only fortified city walls remaining in the Americas north of Mexico. This area was declared a World Heritage Site by UNESCO in 1985 as the "Historic District of Old Québec"; the city's landmarks include the Château Frontenac hotel that dominates the skyline and the Citadelle of Quebec, an intact fortress that forms the centrepiece of the ramparts surrounding the old city and includes a secondary royal residence.
The National Assembly of Quebec, the Musée national des beaux-arts du Québec, the Musée de la civilisation are found within or near Vieux-Québec. According to the Government of Canada, the Government of Quebec and the Geographical Names Board of Canada, the names of Canadian cities and towns have only one official form. Thus, Québec is spelled with an accented é in both Canadian English and French. In English, the city and the province are distinguished by the fact that the province does not have an accented é and the city does. Informally, the accent is omitted in common usage, so the unofficial form "Quebec City" is used to distinguish the city from the province. In French, the names of provinces are gendered nouns and the names of cities are not, so the city and the province are distinguished by the presence or absence of a definite article in front of the name. For example, the concept of "in Quebec" is expressed as "à Québec" for the city and "au Québec" for the province. Quebec City is one of the oldest European settlements in North America and the only fortified city north of Mexico whose walls still exist.
While many of the major cities in Latin America date from the 16th century, among cities in Canada and the U. S. few were created earlier than Quebec City. It is home to the earliest known French settlement in North America, Fort Charlesbourg-Royal, established in 1541 by explorer Jacques Cartier with some 400 persons but abandoned less than a year due to the hostility of the natives and the harsh winter; the fort was in the suburban former town of Cap-Rouge. Quebec was founded by Samuel de Champlain, a French explorer and diplomat, on 3 July 1608, at the site of a long abandoned St. Lawrence Iroquoian settlement called Stadacona. Champlain called "The Father of New France", served as its administrator for the rest of his life; the name "Canada" refers to this settlement. Although the Acadian settlement at Port-Royal was established three years earlier, Quebec came to be known as the cradle of North America's Francophone population; the place seemed favourable to the establishment of a permanent colony.
The population of the settlement remained small for decades. In 1629 it was captured by English privateers, led during the Anglo-French War. Samuel de Champlain argued that the English seizing of the lands was illegal as the war had ended, worked to have the lands returned to France; as part of the ongoing negotiations of their exit from the Anglo-French War, in 1632 the English king Charles agreed to return the lands in exchange for Louis XIII paying his wife's dowry. These terms were signed into law with the Treaty of Saint-Germain-en-Laye; the lands in Quebec and Acadia were returned to the French Company of One Hundred Associates. In 1665, there were 550 people in 70 houses living in the city. One-quarter of the people were members of religious orders: secular priests, Ursulines nuns and the order running the local hospital, Hotel-Dieu. Quebec City was the headquarters of many raids against New England during the four French and Indian Wars. In the last war, the French and Indian War, Quebec City was captured by the British in 1759 and held until the end of the war in 1763.
It was the site of three battles during Seven Years' War: a French victory. France ceded New France, including the city, to Britain in 1763. At the end of French rule in 1763, villages and pastures surrounded the town of 8,000 inhabitants; the town distinguished itself by its monumental architecture and affluent homes of masonry and shacks in the suburbs of Saint-Jean and Saint-Roch. Despite its urbanity and its status as capital, Quebec City remained a small colonial city with close ties to its rural surroundings. Nearby inhabitants traded their farm surpluses and firewood for imported goods from France at the two city m
Ettore Majorana was an Italian theoretical physicist who worked on neutrino masses. On March 25, 1938, he disappeared under mysterious circumstances while going by ship from Palermo to Naples; the Majorana equation and Majorana fermions are named after him. In 2006, the Majorana Prize was established in his memory. There are several categories of scientists in the world. There is the first rank, those who make important discoveries, fundamental to scientific progress, but there are the geniuses, like Galilei and Newton. Majorana was one of these. Majorana was born in Sicily. Mathematically gifted, he was young when he joined Enrico Fermi's team in Rome as one of the "Via Panisperna boys", who took their name from the street address of their laboratory, his uncle Quirino Majorana was a physicist. He began his university studies in engineering in 1923 but switched to physics in 1928 at the urging of Emilio Segrè, his first papers dealt with problems in atomic spectroscopy. His first paper, published in 1928, was written when he was an undergraduate and coauthored by Giovanni Gentile, Jr. a junior professor in the Institute of Physics in Rome.
This work was an early quantitative application to atomic spectroscopy of Fermi's statistical model of atomic structure. In this paper and Gentile performed first-principles calculations within the context of this model that gave a good account of experimentally-observed core electron energies of gadolinium and uranium, of the fine structure splitting of caesium lines observed in optical spectra. In 1931, Majorana published the first paper on the phenomenon of autoionization in atomic spectra, designated by him as "spontaneous ionization"; this name has since become conventional, without the hyphen. Majorana earned his Laurea in physics at the University of Rome La Sapienza in 1929. In 1932, he published a paper in the field of atomic spectroscopy concerning the behaviour of aligned atoms in time-varying magnetic fields; this problem studied by I. I. Rabi and others, led to an important sub-branch of atomic physics, that of radio-frequency spectroscopy. In the same year, Majorana published his paper on a relativistic theory of particles with arbitrary intrinsic momentum, in which he developed and applied infinite dimensional representations of the Lorentz group, gave a theoretical basis for the mass spectrum of elementary particles.
Like most of Majorana's papers in Italian, it languished in relative obscurity for several decades. Experiments in 1932 by Irène Joliot-Curie and Frédéric Joliot showed the existence of an unknown particle that they suggested was a gamma ray. Majorana was the first to interpret the experiment as requiring a new particle that had a neutral charge and a mass about the same as the proton. Fermi told him to write an article. James Chadwick proved the existence of the neutron by experiment that year, he was awarded the Nobel Prize for this discovery. Majorana was known for not considering his work to be banal, he wrote only nine papers in his lifetime. "At Fermi's urging, Majorana left Italy early in 1933 on a grant from the National Research Council. In Leipzig, Germany, he met Werner Heisenberg. In letters he subsequently wrote to Heisenberg, Majorana revealed that he had found in him, not only a scientific colleague, but a warm personal friend." The Nazis had come to power in Germany. He worked on a theory of the nucleus which, in its treatment of exchange forces, represented a further development of Heisenberg's theory of the nucleus.
Majorana travelled to Copenhagen, where he worked with Niels Bohr, another Nobel Prize winner, a friend and mentor of Heisenberg. "In the fall of 1933, Majorana returned to Rome in poor health, having developed acute gastritis in Germany and suffering from nervous exhaustion. Put on a strict diet, he became harsh in his dealings with his family. To his mother, with whom he had shared a warm relationship, he had written from Germany that he would not accompany her on their customary summer vacation by the sea. Appearing at the institute less he soon was scarcely leaving his home. For nearly four years he shut himself off from friends and stopped publishing."During these years, in which he published few articles, Majorana wrote many small works on geophysics, electrical engineering and relativity. These unpublished papers, preserved in Domus Galileiana in Pisa have been edited by Erasmo Recami and Salvatore Esposito, he became a full professor of theoretical physics at the University of Naples in 1937, without needing to take an examination because of his "high fame of singular expertise reached in the field of theoretical physics", independently of the competition rules.
Majorana's last-published paper, in 1937, this time in Italian, was an elaboration of a symmetrical theory of electrons and positrons. In 1937, Majorana predicted that in the class of particles known as fermions there should be particles that are their own antiparticles; this is the so-called Majorana fermion. Solution of Majorana's equation yields particles that are their own anti-particle, now referred to as Majorana Fermions. In April 2012, some of what
Nature is a British multidisciplinary scientific journal, first published on 4 November 1869. It is one of the most recognizable scientific journals in the world, was ranked the world's most cited scientific journal by the Science Edition of the 2010 Journal Citation Reports and is ascribed an impact factor of 40.137, making it one of the world's top academic journals. It is one of the few remaining academic journals that publishes original research across a wide range of scientific fields. Research scientists are the primary audience for the journal, but summaries and accompanying articles are intended to make many of the most important papers understandable to scientists in other fields and the educated public. Towards the front of each issue are editorials and feature articles on issues of general interest to scientists, including current affairs, science funding, scientific ethics and research breakthroughs. There are sections on books and short science fiction stories; the remainder of the journal consists of research papers, which are dense and technical.
Because of strict limits on the length of papers the printed text is a summary of the work in question with many details relegated to accompanying supplementary material on the journal's website. There are many fields of research in which important new advances and original research are published as either articles or letters in Nature; the papers that have been published in this journal are internationally acclaimed for maintaining high research standards. Fewer than 8% of submitted papers are accepted for publication. In 2007 Nature received the Prince of Asturias Award for Humanity; the enormous progress in science and mathematics during the 19th century was recorded in journals written in German or French, as well as in English. Britain underwent enormous technological and industrial changes and advances in the latter half of the 19th century. In English the most respected scientific journals of this time were the refereed journals of the Royal Society, which had published many of the great works from Isaac Newton, Michael Faraday through to early works from Charles Darwin.
In addition, during this period, the number of popular science periodicals doubled from the 1850s to the 1860s. According to the editors of these popular science magazines, the publications were designed to serve as "organs of science", in essence, a means of connecting the public to the scientific world. Nature, first created in 1869, was not the first magazine of its kind in Britain. One journal to precede Nature was Recreative Science: A Record and Remembrancer of Intellectual Observation, created in 1859, began as a natural history magazine and progressed to include more physical observational science and technical subjects and less natural history; the journal's name changed from its original title to Intellectual Observer: A Review of Natural History, Microscopic Research, Recreative Science and later to the Student and Intellectual Observer of Science and Art. While Recreative Science had attempted to include more physical sciences such as astronomy and archaeology, the Intellectual Observer broadened itself further to include literature and art as well.
Similar to Recreative Science was the scientific journal Popular Science Review, created in 1862, which covered different fields of science by creating subsections titled "Scientific Summary" or "Quarterly Retrospect", with book reviews and commentary on the latest scientific works and publications. Two other journals produced in England prior to the development of Nature were the Quarterly Journal of Science and Scientific Opinion, established in 1864 and 1868, respectively; the journal most related to Nature in its editorship and format was The Reader, created in 1864. These similar journals all failed; the Popular Science Review survived longest, lasting 20 years and ending its publication in 1881. The Quarterly Journal, after undergoing a number of editorial changes, ceased publication in 1885; the Reader terminated in 1867, Scientific Opinion lasted a mere 2 years, until June 1870. Not long after the conclusion of The Reader, a former editor, Norman Lockyer, decided to create a new scientific journal titled Nature, taking its name from a line by William Wordsworth: "To the solid ground of nature trusts the Mind that builds for aye".
First owned and published by Alexander Macmillan, Nature was similar to its predecessors in its attempt to "provide cultivated readers with an accessible forum for reading about advances in scientific knowledge." Janet Browne has proposed that "far more than any other science journal of the period, Nature was conceived and raised to serve polemic purpose." Many of the early editions of Nature consisted of articles written by members of a group that called itself the X Club, a group of scientists known for having liberal and somewhat controversial scientific beliefs relative to the time period. Initiated by Thomas Henry Huxley, the group consisted of such important scientists as Joseph Dalton Hooker, Herbert Spencer, John Tyndall, along with another five scientists and mathematicians, it was in part its scientific liberality that made Nature a longer-lasti
Walter Heinrich Heitler was a German physicist who made contributions to quantum electrodynamics and quantum field theory. He brought chemistry under quantum mechanics through his theory of valence bonding. In 1922, Heitler began his study of physics at the Karlsruhe Technische Hochschule, in 1923 at the Humboldt University of Berlin, in 1924 at the Ludwig Maximilians University of Munich, where he studied under both Arnold Sommerfeld and Karl Herzfeld; the latter was his thesis advisor when he obtained his doctorate in 1926. From 1926 to 1927, he was a Rockefeller Foundation Fellow for postgraduate research with Niels Bohr at the Institute for Theoretical Physics at the University of Copenhagen and with Erwin Schrödinger at the University of Zurich, he became an assistant to Max Born at the Institute for Theoretical Physics at the Georg-August University of Göttingen. Heitler completed his Habilitation, under Born, in 1929, remained as a Privatdozent until 1933. In that year, he was let go by the university.
At the time Heitler received his doctorate, three Institutes for Theoretical Physics formed a consortium which worked on the key problems of the day, such as atomic and molecular structure, exchanged both scientific information and personnel in their scientific quests. These institutes were located at the LMU, under Arnold Sommerfeld, the University of Göttingen, under Max Born, the University of Copenhagen, under Niels Bohr. Furthermore, Werner Heisenberg and Born had just published their trilogy of papers which launched the matrix mechanics formulation of quantum mechanics. In early 1926, Erwin Schrödinger, at the University of Zurich, began to publish his quintet of papers which launched the wave mechanics formulation of quantum mechanics and showed that the wave mechanics and matrix mechanics formulations were equivalent; these papers put the personnel at the leading theoretical physics institutes onto applying these new tools to understanding atomic and molecular structure. It was in this environment that Heitler went on his Rockefeller Foundations Fellowship, leaving LMU and within a period of two years going to do research and study with the leading figures of the day in theoretical physics, Bohr's personnel in Copenhagen, Schrödinger in Zurich, Born in Göttingen.
In Zurich, with Fritz London, Heitler applied the new quantum mechanics to deal with the saturable, nondynamic forces of attraction and repulsion, i.e. exchange forces, of the hydrogen molecule. Their valence bond treatment of this problem, was a landmark in that it brought chemistry under quantum mechanics. Furthermore, their work influenced chemistry through Linus Pauling, who had just received his doctorate and on a Guggenheim Fellowship visited Heitler and London in Zurich, as Pauling spent much of his career studying the nature of the chemical bond; the application of quantum mechanics to chemistry would be a prominent theme in Heitler's career. While Heitler was at Göttingen, Adolf Hitler came to power in 1933. With the rising prominence of anti-Semitism under Hitler, Born took it upon himself to take the younger Jewish generation under his wing. In doing so, Born arranged for Heitler to get a position that year as a Research Fellow at the University of Bristol, with Nevill Francis Mott.
At Bristol, Heitler was a Research Fellow of the Academic Assistance Council, in the H. H. Wills Physics Laboratory. At Bristol, among other things, he worked on quantum field theory and quantum electrodynamics on his own, as well as in collaboration with other scientific refugees from Hitler, such as Hans Bethe and Herbert Fröhlich, who left Germany in 1933. With Bethe, he published a paper on pair production of gamma rays in the Coulomb field of an atomic nucleus, in which they developed the Bethe-Heitler formula for Bremsstrahlung. Heitler contributed to the understanding of cosmic rays, as well as predicted the existence of the electrically neutral pi meson. In 1936, Heitler published his major work on quantum electrodynamics, The Quantum Theory of Radiation, which marked the direction for future developments in quantum theory; the book appeared in many editions and printings being translated in Russian. After the fall of France in 1940, Heitler was interned on the Isle of Man for several months.
Heitler remained at Bristol eight years, until 1941, when he became a professor at the Dublin Institute for Advanced Studies, arranged there by Erwin Schrödinger, Director of the School for Theoretical Physics. At Dublin, Heitler's work with H. W. Peng on radiation damping theory and the meson scattering process resulted in the Heitler-Peng integral equation. During the 1942–1943 academic year, Heitler gave a course on elementary wave mechanics, during which W. S. E. Hickson took notes and prepared a finished copy; these notes were the basis for Heitler's book Elementary Wave Mechanics: Introductory Course of Lectures, first published in 1943. A new edition was published as Elementary Wave Mechanics in 1945; this version was revised and republished many times, as well as being translated into French and Italian and published in 1949 and in German in 1961. A further revised version appeared as Elementary Wave Mechanics With Applications to Quantum Chemistry in 1956, as well as in German in 1961.
Schrödinger resigned as Director of the School for Theoretical Physics in 1946, but stayed at Dublin, whereupon Heitler became Director. Heitler stayed at Dublin until 1949, when he accepted a position as Ordinarius Professor for Theoretical Physics and Director of the Institute for Theoretical Physics at the University
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism; the concept was expanded to include any interaction with radiative energy as a function of its wavelength or frequency, predominantly in the electromagnetic spectrum, though matter waves and acoustic waves can be considered forms of radiative energy. Spectroscopic data are represented by an emission spectrum, a plot of the response of interest as a function of wavelength or frequency. Spectroscopy in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of physics and astronomy, allowing the composition, physical structure and electronic structure of matter to be investigated at atomic scale, molecular scale, macro scale, over astronomical distances. Important applications arise from biomedical spectroscopy in the areas of tissue analysis and medical imaging. Spectroscopy and spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are used to describe experimental spectroscopic methods.
Spectral measurement devices are referred to as spectrometers, spectrophotometers, spectrographs or spectral analyzers. Daily observations of color can be related to spectroscopy. Neon lighting is a direct application of atomic spectroscopy. Neon and other noble gases have characteristic emission frequencies. Neon lamps use collision of electrons with the gas to excite these emissions. Inks and paints include chemical compounds selected for their spectral characteristics in order to generate specific colors and hues. A encountered molecular spectrum is that of nitrogen dioxide. Gaseous nitrogen dioxide has a characteristic red absorption feature, this gives air polluted with nitrogen dioxide a reddish-brown color. Rayleigh scattering is a spectroscopic scattering phenomenon. Spectroscopic studies were central to the development of quantum mechanics and included Max Planck's explanation of blackbody radiation, Albert Einstein's explanation of the photoelectric effect and Niels Bohr's explanation of atomic structure and spectra.
Spectroscopy is used in physical and analytical chemistry because atoms and molecules have unique spectra. As a result, these spectra can be used to detect and quantify information about the atoms and molecules. Spectroscopy is used in astronomy and remote sensing on Earth. Most research telescopes have spectrographs; the measured spectra are used to determine the chemical composition and physical properties of astronomical objects. One of the central concepts in spectroscopy is its corresponding resonant frequency. Resonances were first characterized in mechanical systems such as pendulums. Mechanical systems that vibrate or oscillate will experience large amplitude oscillations when they are driven at their resonant frequency. A plot of amplitude vs. excitation frequency will have a peak centered at the resonance frequency. This plot is one type of spectrum, with the peak referred to as a spectral line, most spectral lines have a similar appearance. In quantum mechanical systems, the analogous resonance is a coupling of two quantum mechanical stationary states of one system, such as an atom, via an oscillatory source of energy such as a photon.
The coupling of the two states is strongest when the energy of the source matches the energy difference between the two states. The energy of a photon is related to its frequency by E = h ν where h is Planck's constant, so a spectrum of the system response vs. photon frequency will peak at the resonant frequency or energy. Particles such as electrons and neutrons have a comparable relationship, the de Broglie relations, between their kinetic energy and their wavelength and frequency and therefore can excite resonant interactions. Spectra of atoms and molecules consist of a series of spectral lines, each one representing a resonance between two different quantum states; the explanation of these series, the spectral patterns associated with them, were one of the experimental enigmas that drove the development and acceptance of quantum mechanics. The hydrogen spectral series in particular was first explained by the Rutherford-Bohr quantum model of the hydrogen atom. In some cases spectral lines are well separated and distinguishable, but spectral lines can overlap and appear to be a single transition if the density of energy states is high enough.
Named series of lines include the principal, sharp and fundamental series. Spectroscopy is a sufficiently broad field that many sub-disciplines exist, each with numerous implementations of specific spectroscopic techniques; the various implementations and techniques can be classified in several ways. The types of spectroscopy are distinguished by the type of radiative energy involved in the interaction. In many applications, the spectrum is determined by measuring changes in the intensity or frequency of this energy; the types of radiative energy studied include: Electromagnetic radiation was the first source of energy used for spectroscopic studies. Techniques that employ electromagnetic radiation are classified by the wavelength region of the spectrum and include microwave, terahe