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	Atomic Absorption and Emission Spectra
		Thus, emission spectra are produced by thin gases in which the atoms do not experience many collisions (because of the low density).
		The emission lines correspond to photons of discrete energies that are emitted when excited atomic states in the gas make transitions back to lower-lying levels.
		Emission or absorption processes in hydrogen give rise to series, which are sequences of lines corresponding to atomic transitions, each ending or beginning with the same atomic state in hydrogen.
	csep10.phys.utk.edu /astr162/lect/light/absorption.html (408 words)

	Spectra
		Spectra can also be created by the interference of light waves, the phenomenon that makes the brightly colored patterns seen reflected from a compact audio disc and the halos often observed next to a bright, partly clouded Moon.
		Emission lines are easy to produce in the laboratory simply by heating a low-density gas, allowing collisions to kick the electrons to higher energies.
		The differences in stellar spectra, at least for main sequence stars, are caused almost entirely by differences in ionization (after all, if sodium is all ionized, the absorptions of neutral sodium will not be present) and the by the way in which the absorption efficiencies change with temperature.
	www.astro.uiuc.edu /~kaler/sow/spectra.html (5857 words)

	Types of Astronomical Spectra
		Emission spectrum: A third possibility occurs if an observer is not looking directly at a hot fl body source but instead at a diffuse cloud of gas that is not a fl body.
		Emission spectra can be observed in emission nebulae such as M42, the Great Nebula in Orion and the Eta Carinae nebula (shown at right).
		Their spectra show strong emission features and analysis of the Doppler shift of the lines can be used to determine how fast the ejected gas is expanding.
	outreach.atnf.csiro.au /education/senior/astrophysics/spectra_astro_types.html (1732 words)

	Infrared Emission Spectra
		The resulting emission spectra were processed by ratioing the emission from HAC to that of an uncoated stainless steel substrate at the same temperature, followed by a cubic polynomial baseline correction.
		Thermal emission spectra recorded from HAC at various temperatures between 425 and 775 K are shown in Figures 1 and 2.
		Spectra in Figures 1 and 2 suggest that small particles of HAC will emit IR spectral features very similar to those observed in astronomical sources when their temperature is raised to 700
	ecf.hq.eso.org /~ralbrech/sepdec97apjl/975452.html (1954 words)

	ASU Spectral Library (Site not responding. Last check: 2007-09-21)
		The new spectra are not yet included in the searchable database, but are available for download.
		The emphasis in developing this library has been to obtain spectra of the purest samples possible for comparison to spectra obtained from planetary and Earth-orbiting spacecraft, airborne instruments, and laboratory measurements.
		Emission spectra were acquired using a Nicolet Nexus 670 interferometric spectrometer equipped with a CsI beamsplitter and an uncooled deuterated triglycine sulfate (DTGS) detector; the spectral range of the instrument is from 2000 — 220 cm
	tes.asu.edu /speclib (1033 words)

	Olympus Microscopy Resource Center: Specialized Microscopy Techniques - Fluorescence - Excitation and Emission ...
		To determine the Emission spectrum of a given fluorochrome, the dye absorption maximum wavelength (usually the same as the excitation maximum) is found and the fluorochrome is excited at that maximum.
		The emission maximum is chosen and only emission light at that emission wavelength is allowed to pass to the detector.
		The emission intensity peak is usually lower than the excitation peak; and the emission curve is often a mirror image of the excitation curve, but shifted to longer wavelengths.
	www.olympusmicro.com /primer/techniques/fluorescence/excitation.html (1612 words)

	Emission spectra (Site not responding. Last check: 2007-09-21)
		Diverse elements emit diverse phantoms of emission when they are excited because each type of element has a rind of the energy or a unique system of the energy level.
		A long-range extension of this is the capacity to measure amounts of an element measuring the brightness of the emitted light.
		The lines of emission can be considered when you watch through the spectroscope the light source.
	spectra.thestas.com /emission-spectra.htm (2647 words)

	Excitation and Emission of Green Fluorescent Proteins \| Technical Notes
		Here we characterize the excitation and emission spectra of some of the commonly used variants of GFP and recommend appropriate filter sets for detection and quantitation using the FL600 microplate fluorescence reader.
		Note that although the 508/20 emission filter is closer to the emission peak of the sample, overlap with the 485/20 filter precludes the use of that filter, necessitating the use of the 530/25 nm filter.
		These data are in close agreement with the excitation and emission spectra of the proteins portrayed in Figure 1.
	www.biotek.com /products/tech_res_detail.php?id=54 (775 words)

	Lab Discrete Spectra
		Investigate quantitatively the emission spectrum of hydrogen and relate it to Bohr's theory of atomic structure.
		In a sense the characteristic emission lines of any gas act as a "fingerprint" which clearly identifies the composition of the gas.
		Bohr's complete model for hydrogen predicts that emission lines correspond to the emission of a photon that occurs when an electron makes the transition from a higher energy state to a lower energy state.
	www.emporia.edu /physics/keithron/collegelab2/spectra.htm (695 words)

	Experiment 2: Atomic Emission Spectra
		As it turns out, when the light from a colored flame is observed through a prism, rather than a continuous rainbow of colors, sharp lines of individual colors appear.
		Carefully observe the other elemental emission spectra in the laboratory using both the fiber optic and the diffraction grating.
		For two of the additional samples, collect and print the emission spectrum from the laptop and note the ID number of the ‘tube’ of gas for each ‘unknown’ you choose.
	www.lawrence.edu /dept/chemistry/courses/CHEM111/atomic_emission.htm (698 words)

	Emission Spectra
		Conveniently for the purposes of this experiment, the electronic spectra of the elements fall largely within the range of energies (wavelengths) that are detected by the human eye ("visible light").
		One of the curious observations of the mid-nineteenth century that defied explanation for nearly fifty years was the fact that unlike the continuous "rainbow" spectra emitted by the Sun or a white light, the spectra emitted by a single element consisted of a small number of discrete lines.
		E is the difference in energy between two states of the atom and is equal to the energy of the light photon emitted or absorbed when the atom undergoes a transition between the two states.
	web.centre.edu /che/che131_lab/emission.htm (1241 words)

	Emission Spectra of --Conjugated Organosilicon Copolymers Consisting of Alternating Dimethylsilylene and Aromatic Units
		Emission Spectra of --Conjugated Organosilicon Copolymers Consisting of Alternating Dimethylsilylene and Aromatic Units
		The solvatochromism of the emission spectra was observed for the organosilicon copolymers, where the emission maximum shifted to longer wavelength in polar solvents.
		The molecular orbital calculations on a model compound suggest that the vibronically structured emission is attributed to the
	pubs.acs.org /cgi-bin/abstract.cgi/mamobx/1996/29/i21/abs/ma960398c.html (205 words)

	Cool Cosmos
		The examples of these types of spectra shown below are for visible light as it is spread out from purple to red, but the concept is the same for any region of the electromagnetic spectrum.
		An emission spectra occurs when the atoms and molecules in a hot gas emit extra light at certain wavelengths, causing bright lines to appear in a spectra.
		The shape of the continuous spectra (often refered to as the continuum) on a plot is dependent on temperature and motion of the emitting gas.
	coolcosmos.ipac.caltech.edu /cosmic_classroom/ir_tutorial/spec.html (706 words)

	BD Biosciences : Protocols : Fluorochrome Absorption and Emission Spectra
		Here we present the absorption and emission spectra of the fluorochromes BD Biosciences Pharmingen conjugates to monoclonal antibodies and other proteins.
		FITC has a high quantum yield (efficiency of energy transfer from absorption to emission fluorescence) and approximately half of the absorbed photons are emitted as fluorescent light.
		Individual fluorochrome excitation spectra are found in gray and the corresponding emission spectra in fl.
	www.bdbiosciences.com /pharmingen/protocols/Fluorochrome_Absorption.shtml (1871 words)

	PSRD: Using TES to interpret the composition of the Martian surface
		Using mathematical mixing calculations based on the thermal emission spectra of numerous materials, the TES team reported in papers led by Josh Bandfield and Victoria Hamilton that the two regions had mineral abundances similar to basalt (Surface Type 1) and andesite (Surface Type 2), two common volcanic rock types on Earth.
		The intensity at different wavelengths (called spectra) allow experts like Phil Christensen and his team to deduce some physical properties of the surface, such as the abundance of boulders versus dust.
		Quantitative assessments of the quality of the match between measured and calculated spectra indicate that all matches are very good--another example of how tricky it is to determine mineralogy from thermal emission data.
	www.psrd.hawaii.edu /May02/MarsTES.html (2298 words)

	Time Resolved Emission Spectra (Site not responding. Last check: 2007-09-21)
		Fluorescence spectra recorded, or constructed, by resolving single photon pulses that have been selected from a limited time interval are referred to as time resolved emission spectra (TRES).
		Time-gated spectra of the overall emission decays are measured by scanning the emission monochromator whilst sweeping the Multi Channel Scaler of the MCA.
		At early times when the emission intensity is at its maximum (at t = 0 by definition) a narrow timeslice window may be used successfully.
	www.chem.rochester.edu /~cpct/tres.htm (392 words)

	Spectra of Gas Discharges
		Spectra of neutral and singly ionized elements from the Astronomical Data Center (ADC) catalog A6016, by Reader J., Corliss Ch.H. :1981, 'Line Spectra of the Elements', CRC Handbook of Chemistry and Physics; NSRDS-NBS 68
		The simulated gas discharge spectrum is synthesized by assigning each emission line to a gaussian and each point in the spectra is computed as a mathematical sum of all the emission lines.
		Most of the time spectra taken by researchers do not fully resolve the intrinsic line profile so the lines are broadened mainly by instrumental imperfection.
	astro.u-strasbg.fr /~koppen/discharge (1281 words)

	Galaxies and the Universe - Emission -Line Spectra
		Because various emission lines sample different regimes of temperature, density, and ionization, emission spectra are uniquely powerful probes of conditions around active nuclei.
		Thus all the structure and widths seen in AGN spectra are from mass motions or some scattering process that can smear frequencies very strongly (a role for electron scattering has been found in a few cases).
		The very existence of strong line emission tells us that there must be strong UV radiation from the AGN, and the line ratios tell us that its spectral shape is quite different from a stellar distribution.
	www.astr.ua.edu /keel/galaxies/emission.html (2855 words)

	Bohr Theory
		Because of their unique nature, atomic spectra are also referred to as the "fingerprints of the elements." The series of lines of color that an atom will produce is related to the locations of the electrons on that atom and their relationship with the nucleus.
		Atomic spectra were fundamental pieces of experimental information used by chemists in the development of the electronic structures of atoms.
		A continuous spectrum, or rainbow, when observed in nature, is usually the result of the spectra of many elements superimposed on top of each other.
	www.bcpl.net /~kdrews/bohr/bohr.html (904 words)

	Emission Spectroscopy: Element identification
		Different elements emit different emission spectra when they are excited because each type of element has a unique energy shell or energy level system.
		pectroscopy is the analysis of light spectra and the way in which light interacts with matter.
		The emission lines can be seen when you look through the spectroscope at the light source.
	www.800mainstreet.com /spect/emission-flame-exp.html (2115 words)

	NewsHour Extra Lesson Plan: Stellar Fingerprints: The Spectra of Stars
		Prepare for the emission spectra activity by placing the hydrogen discharge tube into the power supply and positioning it so students can use diffraction gratings to create a hydrogen emission spectrum.
		Now that students understand how emission spectra are produced and that each element has a unique pattern, use Activity Sheet 3: "Comparing Emission and Absorption Spectra" and/or Overhead B: "The Emission and Absorption Spectra for Hydrogen" to show students the emission and absorption spectra for hydrogen.
		Once students have studied the two spectra, ask them to predict the absorption pattern produced by element X by drawing the absorption lines in the area provided on Activity Sheet 3: "Comparing Emission and Absorption Spectra." In this case, element X is lithium.
	www.pbs.org /newshour/extra/teachers/lessonplans/science/hubble.html (2414 words)

	Atomic Emission Spectra - the Origin of Spectral Lines
		The spectral lines in the visible region of the atomic emission spectrum of barium are shown below.
		No two elements have the same atomic emission spectrum; the atomic emission spectrum of an element is like a fingerprint.
		The diagram to the right illustrates the formation of three series of spectral lines in the atomic emission spectrum of hydrogen.
	www.avogadro.co.uk /light/bohr/spectra.htm (848 words)

	PES 105 Light: Spectroscopy and Atoms
		Here is a link to a nice exercise discussing the various types of spectra.
		emission spectrum: If an electron jumps down from a higher level to a lower level, light with a specific energy (wavelength) will be emitted.
		Link to animation showing emission spectrum and atomic orbits.
	www.uccs.edu /~tchriste/courses/PES105/105lectures/105lecspectro.html (252 words)

	Nebulae (Site not responding. Last check: 2007-09-21)
		Emission Nebulae: Emit light because the atoms in their gases are excited by high energy radiation of stars involved.
		Therefore, their spectra are the same as those of the stars, typically continuous spectra.
		Absorption Nebulae or Dark Nebulae: Absorb light: Their gas component can be seen as absorption spectra in the light of background stars, their dust component by absorbing and reddening background light.
	www.seds.org /messier/nebula.html (731 words)

	ASU Thermal Emission Laboratory
		The Mars Thermal Emission Spectrometer research group at ASU is busy compiling a spectral library of Earth's minerals and rocks for comparison to spectra to be obtained from Mars.
		See spectra on Melissa Lane's carbonate page or her phosphates, sulfates, and chlorides page.
		Studies of minerals are very useful for learning about the spectral differences in minerals that can have variable structures or compositions, but in the natural environment, very few minerals occur alone in large quantities -- most minerals are found with a group of other minerals in rocks.
	tes.asu.edu /newlab.html (1021 words)

	Plasma Laser Stars 1977 Paper
		Examination of the spectra clearly indicates that this is almost entirely due to the sudden increase in the strength of the carbon band.
		The defining characteristic of this class is the presence of emission lines due to the O VI doublet λλ3811, 3834 among the strongest lines in the spectrum.
		Quite often similarities in the spectra of two or more stars also imply similarities in some of their other properties, e.g., absolute magnitude, temperature and mass; but it is well to bear in mind that it is not neces- sarily always so.
	www.laserstars.org /V1977 (7924 words)

	Thermal Emission Spectra from the Infrared Interferometer Spectrometer (IRIS) on Nimbus 3 and 4
		Thermal Emission Spectra from the Infrared Interferometer Spectrometer (IRIS) on Nimbus 3 and 4
		The Infrared Interferometer Spectrometer (IRIS) on Nimbus 3 and 4 measured thermal emission of the Earth and its atmosphere in the spectral range of 5 to 20 micrometers, with nominal spectral resolutions of 5 and 1.4 cm**-1, respectively.
		On the archival tapes are calibrated atmospheric spectra along with reference calibration, average instrument temperature, summary information for each orbital pass, and documentation.
	gcmd.gsfc.nasa.gov /records/GCMD_NIMBUS_IRIS.html (191 words)

	Effect of Chlorinated Hydrocarbons on the Fluorescence Emission Spectra of 1,3-Bis-(1-pyrene) Propane in Solutions and ... (Site not responding. Last check: 2007-09-21)
		Changes in the emission spectra of bpp in methanol solutions, upon addition of methylene chloride, chloroform, or carbon tetrachloride, are described.
		Changes in both the excitation and emission spectra of bpp in CC4, are related to exciplex formation, leading to irreversible formation of photochemical products.
		A rapid decrease in bpp excimer emission, upon exposure to CC4, vapors, was observed.
	www.s-a-s.org /journal/96/asv50n12/ASv50n12_sp6.html (255 words)

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