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Topic: Emission spectrum

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	Atomic Absorption and Emission Spectra
		An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies; since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon, this gives rise to dark lines (absence of light) in the spectrum.
		The spectrum of hydrogen is particularly important in astronomy because most of the Universe is made of hydrogen.
		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)

	Olympus FluoView Resource Center: Glossary of Terms in Confocal Microscopy
		Typically, the fluorescence emission spectrum, which is plotted as relative intensity as a function of wavelength, is positioned in a region of longer wavelengths than the stimulating excitation spectrum (in effect, the average wavelength of emission is longer than the average wavelength of excitation).
		Excitation spectra are generated by scanning through the absorption spectrum of a fluorochrome or fluorophore while monitoring the emission at a single (peak) wavelength.
		Fluorescence emission from the specimen is refocused at the same pinhole in the disk to provide the same function in rejecting out-of-focus light as the single pinhole in a conventional confocal microscope.
	www.olympusfluoview.com /theory/glossary.html (10049 words)

	Absorption spectrum
		A related phenomenum to the emission spectra of elements is the absorption spectra.
		As with the emission spectrum, each element has its own unique absorption spectrum, as the energy levels of different elements differ.
		Measuring the absorption spectrum can therefore be used to identify elements in an unknown substance by comparing it to the spectrum of known elements.
	theory.uwinnipeg.ca /mod_tech/node152.html (219 words)

	Olympus Microscopy Resource Center: Light and Color - Fluorescence - Overview of Excitation and Emission Fundamentals
		The absorption spectrum of a typical fluorochrome is illustrated in Figure 1(a) where the relative intensity of absorption is plotted against the measured wavelength.
		The relative intensity of the fluorescence is measured at the various wavelengths to plot the emission spectrum, as illustrated in Figure 1(b).
		This overlap of excitation and emission intensities and wavelengths (illustrated in Figure 1(c)) must be eliminated, in fluorescence microscopy, by means of the appropriate selection for an excitation filter, dichromatic beamsplitter (in reflected light fluorescence), and barrier or emission filter.
	www.olympusmicro.com /primer/lightandcolor/fluoroexcitation.html (0 words)

	Emission Experiment from MeasureNet
		Hence, the spectrum is called a line spectrum; it is also called an atomic emission spectrum, since it is produced by emission of light from excited atoms.
		Unlike the procedure for recording the emission spectrum of fluorescent lights, the emission of light from the flame is not steady.
		Examine this spectrum carefully to see whether any of the "extraneous" lines in the experimental H atom spectrum may be assigned to traces of oxygen present and therefore excluded from the analysis.
	www.oceanoptics.com /applications/emissionexperiment.asp (0 words)

	Active Galaxies and Quasars - Emission Spectrum of NGC 4151 (Site not responding. Last check: )
		Seyfert galaxies were originally noted for the strength and broadening of their emission lines, and as a class were later characterized by the high ionization states of many of the atomic and ionized species producing these lines.
		This composite spectrum of the archetypal Seyfert NGC 4151 shows the wide variety of emission lines present, from the Lyman limit at 912 A to the mid-infrared at about 9 microns.
		ISO scanned the wavelengths of strong emission lines in great detail, but skipped most of the intervening wavelengths, accounting for the blocky appearance of the deep infrared spectrum.
	www.astr.ua.edu /keel/agn/ngc4151sp.html (565 words)

	Emission spectrum
		A material's emission spectrum is the amount of electromagnetic radiation of each frequency it emits when it is heated (or more generally when it is excited).
		The emission spectrum can be used to determinate the composition of a material, since it is different for each element of the periodic table.
		Interestingly, the emission spectrum of an element is the exact opposite of its absorption spectrum; that is, the frequencies emitted by a material when heated are the only frequencies that will be absorbed when it is lighted with a white light.
	www.xasa.com /wiki/en/wikipedia/e/em/emission_spectrum.html (160 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.
		The spectrum formed is an emission or bright line spectrum, as shown by the middle spectrum in Figure 1.
		The overall spectrum of a galaxy is simply the combined spectrum of all the stars and other radiating matter in the galaxy.
	outreach.atnf.csiro.au /education/senior/astrophysics/spectra_astro_types.html (1731 words)

	Photons and Light
		Spectrum, in optics, the arrangement according to wavelength of visible, ultraviolet, and infrared light.
		An emission spectrum consists of all the radiations emitted by atoms or molecules, whereas in an absorption spectrum, portions of a continuous spectrum (light containing all wavelengths) are missing because they have been absorbed by the medium through which the light has passed; the missing wavelengths appear as dark lines or gaps.
		The spectrum of incandescent gases, on the other hand, is called a line or emission spectrum because only a few wavelengths are emitted.
	zebu.uoregon.edu /2000/ph101/lec05.html (624 words)

	Principles of Spectroscopy
		The spectrum produced is a set of bright emission lines, so it is called an emission spectrum.
		We will start with the light on the lowest voltage necessary to see the spectrum, then slowly turn it all the way up to 120 V. Watch the spectrum as the voltage is turned up, especially the relative strengths of the colors.
		The spectrum is projected onto a scale to the left of the light source.
	www.astro.lsa.umich.edu /~janagrc/DA5.html (1730 words)

	Time Resolved Emission Spectra (Site not responding. Last check: )
		This is the measurement of the evolution of the emission spectrum with time.
		Time-gated spectra of the overall emission decays are measured by scanning the emission monochromator whilst sweeping the Multi Channel Scaler of the MCA.
		Several scans across this spectrum may be required if the count rate is low for a particular time slice, which occurs at late times when the emission decay intensity is low.
	chem.chem.rochester.edu /~stc/tres.htm (392 words)

	Astronomy (Site not responding. Last check: )
		The wavelength is the distance between the beginning and end of a complete cycle of the light wave or the distance from one crest to the next.
		This spectrum consists of a continuous set of emission lines side by side, with no gaps, and appearing as a smooth transition of all colors from red to violet.
		This spectrum appears as a continuous spectrum of all colors with a number of gaps or dark lines throughout it.
	slohs.slcusd.org /pages/teachers/rhamley/Astronomy/Spectroscopy/spectrolab.html (425 words)

	Overview of Solar Flares
		The X rays and gamma rays are produced by several different processes with the result that a complex spectrum is produced involving both line and continuum emission.
		A composite spectrum of a large flare is shown in the figure below, where the contributions to the total emission are indicated in the different energy ranges.
		This type of emission from a plasma at a given temperature has a characteristic continuum spectrum that falls off exponentially with increasing energy, the e-folding energy being a measure of the temperature of the plasma.
	hesperia.gsfc.nasa.gov /~holman/hessi/flares.htm (1239 words)

	Atomic Absorption and Emission Spectra
		We may view a continuum spectrum as an emission spectrum in which the lines overlap with each other and can no longer be distinguished as individual emission lines.
		An absorption spectrum occurs when light passes through a cold, dilute gas and atoms in the gas absorb at characteristic frequencies; since the re-emitted light is unlikely to be emitted in the same direction as the absorbed photon, this gives rise to dark lines (absence of light) in the spectrum.
		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.
	www.cartage.org.lb /en/themes/Sciences/Astronomy/Modenastronomy/Interactionoflight/AtomicAbsorption/AtomicAbsorption.htm (0 words)

	UV and Fluorescence Spectral Studies of Proteins
		Thus for a fluorophore, two separate spectra can be collected: an absorption spectrum- usually referred to as an excitation spectrum- where the fluorescence emission is observed at a fixed wavelength and the excitation wavelength is scanned; and a fluorescence emission spectrum, where the excitation wavelength is fixed and the emission wavelength scanned.
		With emission spectra it is usual to initially fix the exciting wavelength at the absorption maximum for the molecule and scan through longer wavelengths with the emission monochrometer to establish the emission maximum.
		Once the emission maximum has been established, the emission monochrometer is set at that wavelength and the excitation monochrometer scanned to define the excitation spectrum.
	www.richmond.edu /~jbell2/chem327lab5.html (1779 words)

	UVES sky emission spectrum
		This spectrum is the combination of airglow emission lines, telluric absorption lines and the solar spectrum due to scattered moonlight.
		In the red spectra, the plotted spectrum is repeated on a compressed scale (factor 5 or 10 as indicated in the plots, red curve).
		The UVES sky emission spectrum starts at 3140 A and extends down to 10,400 A. There is a plethora of faint emission lines up to about 4400 A, up to 100 lines per 100A interval.
	www.eso.org /observing/dfo/quality/UVES/pipeline/sky_spectrum.html (0 words)

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