Temperature jump method laser heating

Generally, ROH or B is an indicator, so that RO-HB+ absorbs strongly in the visible region of the spectrum, and its concentration may be determined spectrophotometrically. The kinetics of reactions of this type have been observed by the temperature-jump method with microwave or laser heating. 

The apphcation of the laser-induced temperature jump method requires that the only effect of the laser pulses is the heating of the electrode surface, resulting in a sudden temperature change at the interphase. In this regard, the laser ptrlses employed in the experiments described in Section V (wavelength of 532 run, drrration of... 

A major advance in the investigation of the intramolecular dynamics of spin equilibria was the development of the Raman laser temperature-jump technique (43). This uses the power of a laser to heat a solution within the time of the laser pulse width. If the relaxation time of the spin equilibrium is longer than this pulse width the dynamics of the equilibrium can be observed spectroscopically. At the time of its development only two lasers had sufficient power to cause an adequate temperature rise, the ruby laser at 694 nm and the neodymium laser at 1060 nm. Neither of these wavelengths is absorbed by solvents. Various methods were used in attempts to absorb the laser power, with partial success for microsecond relaxation times. 

A third simple and generally applicable method is temperature jump, to perturb a pre-existing chemical or structural equilibrium. However, limitations on thermal conductivity mean that thermal equilibration in response to an external heat pulse is slow [22, 24], This points to the use of IR lasers that excite the crystal directly (unpublished results of Volz, K., Spirgatis, A. and Moffat, K.). 

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