Rapid scan spectroscopy

Rapid removal of enzyme stabilizing agents, RAPID BUFFER EXCHANGE RAPID SCAN SPECTROSCOPY OF FAST REACTIONS... 

Direct correlation between thermal radiation spectroscopic techniques and thermocouple temp measurements have been obtained for a pyrot mixt containing the agent CS and the simulant 1-methylaminoanthraquinone (Ref 28). Using rapid-scan spectroscopy for time resolution of the reaction, together with two-line analysis and max radiant energy wavelength techniques, the spatial, temporal and thermal history is documented... 

In optical pyrometry the size of the luminous object must meet a certain minimum, and the radiant energy output must be uniform over the area observed, lest the apparent temp be low. Moreover, temp readings will be low if radiant energy is absorbed in the colder outer gas envelope. The role of smoke and other debris in the study of expls was alluded to in an earlier article ( Spectroscopy of Energetic Materials in this Vol). There, too, was referenced rapid scan spectroscopy for the resolution of pyrot phenomena, and of the energetics of fuel-air expins. For more extensive discussions of high temp measurement techniques, see Ref 6a... 

The d-d absorption of the copper complex differs in each step of the catalysis because of the change in the coordination structure of the copper complex and in the oxidation state of copper. The change in the visible spectrum when phenol was added to the solution of the copper catalyst was observed by means of rapid-scanning spectroscopy [68], The absorbance at the d-d transition changes from that change the rate constants for each elementary step have been determined [69], From the comparison of the rate constants, the electron transfer process has been determined to be the rate-determining step in the catalytic cycle. 

When the heterogeneous electron transfer is followed by a chemical step, the registration of spectral data becomes more complicated unless the rate of the chemical reaction is very low. Rapidly reacting species—for instance, radical ions—can be characterized spectroscopically by the application of rapid scan spectroscopy (RSS), modulated specular reflectance spectroscopy (MSRS) and, more recently, diode array spectrometers. 

Problem 8.28 Consider styrene polymerization by triflic (trifluoroethanesul-fonic) acid in 1,2-dichloroethane at 20°C where is 4.2x10 mol/L (23]. For experiments performed (using stopped-flow rapid scan spectroscopy) at a styrene concentration of 0.397 M and acid concentration of 4.7x10 M at 20°C, the maximum concentration of cationic ends (both free ions and ion pairs) was found [23] to be 1.4x10 M, indicating that the initiator efficiency is 0.030. At 20°C, kf / is reported [23] to be 12. 

The simple technique of dilatometry, described earlier (p. 324), cannot be used to measure rates of anionic living polymerizations as the reactions proceed too rapidly. For such fast reactions, the so-called stopped-fiow technique (Sawamoto and Higashimura, 1978,1979,1986,1990) is useful. In stopped-fiow, rapid-scan spectroscopy, separate solutions of monomer and initiator are mixed instantaneously in a mixing chamber and forced into a capillary tube inside a spectrophotometer where the fiow is stopped and the change in absorbance of propagating species or monomer is measured with time. 

Rapid-scanning spectroscopy (RSS) is a method in which a selected portion of the ultraviolet, visible, or near-infrared spectrum is scanned on a time scale ranging from several sec to a few /isec. The applications of this technique to systems in which short-lived transient species exist or large reaction rates are encountered are numerous... 

H. L., Rapid Scanning Spectroscopy Prelude to a New Era in Analytical Spectroscopy, Anal. Chem., 45, 915A... 

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