Molecular emission

Single-Bubble Sonoluminescence. The spectra of MBSL and SBSL are dramatically different. MBSL is generally dominated by atomic and molecular emission lines, but SBSL is an essentially featureless emission that iacreases with decreasiag wavelength. For example, an aqueous solution of NaCl shows evidence of excited states of both OH- and Na ia the MBSL spectmm however, the SBSL spectmm of an identical solution shows no evidence of either of these peaks (30). Similady, the MBSL spectmm falls off at low wavelengths, while the SBSL spectmm continues to rise, at least for bubbles containing most noble gases (38). 

M + e + hv). The structured background is produced by partially or completely overlapping atomic, ionic, or in some cases, molecular emission. To obtain precision better than 10% the concentration of an element must be at least 5 times the detection limit. 

Vol. 129. Flame Chemiluminescence Analysis by Molecular Emission Cavity Detection. Edited by David Stiles, Anthony Calokerinos, and Alan Townshend... 

The simultaneous analysis of orthophosphate, glycerol phosphates, and inositol phosphates has been achieved by spectrophotometric analysis of the molybdovanadate complexes. Also, a sensitive and selective chemiluminescent molecular emission method for the estimation of phosphorus and sulphur is described, which is based on passing solutions into a cool, reducing, nitrogen-hydrogen diffusion flame. For organic compounds it was usually necessary to prepare test solutions by an oxygen-flask combustion technique. 

Electroanalytlcal Stripping Methods. By Khjena Z. Brainina and E. Neyman Air Monitoring by Spectroscopic Techniques. Edited by Markus W. Sigrist Information Theory in Analytical Chemistry. By Karel Eckschlager and Klaus Danzer Flame Chemiluminescence Analysis by Molecular Emission Cavity Detection. Edited by... 

Didenko YT, McNamara WB, Suslick KS (2000) Molecular emission from single-bubble sonoluminescence. Nature 407 877-879... 

The second step in the reaction, dissociation of the Hej Rydberg molecule, is similar to dissociative recombination of He with a free electron. For this reason, Bates73 called this recombination mechanism Rydberg dissociative recombination. It enhances the overall loss rate of free electrons because the stabilization of He2 prevents the return of weakly bound electrons to the population of free electrons. The reaction plays the same role as the reaction of H with H2 that we discussed in Section IV.C. As has been discussed by Bates, the mechanism also provides an explanation for spectroscopic observations of atomic and molecular emissions in helium afterglows. There is direct evidence for the existence of a substantial population of weakly bound electrons in helium afterglows.74 Most likely, the weakly bound electrons are Rydberg electrons in He2 molecules. 

The hottest stars have absorption features in the photosphere associated with lighter elements, some in highly ionised states, but the lower temperature stars have a more diverse atomic composition the coolest stars show molecular emission spectra. This suggests an evolution of stars that involves the formation of heavier elements and ultimately molecules. 

Figure 7 Emission spectra obtained in the reaction of DMS with F2. (A) 155 mtorr CH3SCH3, 30 mtorr F2, 570 mtorr He (B) 30 mtorr CH3SCH3, 20 mtorr F2, 350 mtorr He (C) 30 mtorr CH3SCH3, 50 mtorr F2, 900 mtorr He. (Reprinted from RJ Glinski, EA Mishalanie, JW Birks, Molecular emission spectra in the visible and near IR produced in the chemiluminescent reactions of molecular fluorine with organosulfur compounds, Journal of Photochemistry 37 223, 1987, with permission from Elsevier Science.)...

Instead of AES the molecular emission of SnO can be stimulated in an oxycavity placed in a H2/N2 flame, and measured at 408 nm. The recommended sample preparation consists of hydride generation and concentration by cold-trap collection LOD 80 pg Sn(II)/L in a 1 mL sample36. 

Nuclear Conditions for Concentration Accumulation Molecular emission nuclear fusion energy... 

Molecular emission is referred to as luminescence or fluorescence and sometimes phosphorescence. While atomic emission is generally instantaneous on a time scale that is sub-picoseconds, molecular emission can involve excited states with finite, lifetimes on the order of nanoseconds to seconds. Similar molecules can have quite different excited state lifetimes and thus it should be possible to use both emission wavelength and emission apparent lifetime to characterize molecules. The instrumental requirements will be different from measurements of emission, only in detail but not in principles, shared by all emission techniques. 

Molecular emissions are due to electronic transitions within the molecule but are modified by variations in bond length. The bond between two atoms assumes a particular length as a result of the various forces acting upon the atoms involved. The attractive forces between the electrons of one atom and the nucleus of the other atom are balanced by the repulsive forces of the like-charges carried by both nuclei. The Morse curve (Figure 2.10) describes... 

Amino acids can be determined in a two-step process (reaction 26). The SO2 produced can be determined by measuring the S2 emission of an N2-H2 flame in a molecular emission cavity. Carbon was found to be better than iron for building the cavity376. 

ECO = electron capture detector ED = electrochemical detector FID st flame ionization detector GC = gas chromatography HECD = Hall s electrolytic conductivity detector HPLC = high performance liquid chromatography MEC = molecular emission cavity analysis MS - mass spectrometry HD = photo-ionization detector... 

Abdel-Kader MHK, Peach ME, Stiles DA. 1979. Determination of ethylene dibromide in fortified soils by molecular emission cavity analysis using a modified extraction process. J Assoc Off Anal Chem 62 114-118. 

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