Temperature jump infrared

Laser-Induced Temperature Jump Infrared Measurements of RNA Folding... 

An alternative method of overcoming the time delay of mixing is to use a relaxation method. An equilibrium mixture of reagents is preincubated and the equilibrium is perturbed by an external influence. The rate of return, or relaxation, to equilibrium is then measured. The most common procedure for this is temperature jump (Figure 4.6).13 A solution is incubated in an absorbance or fluorescence cell and its temperature is raised through 5 to 10°C in less than a microsecond by the discharge of a capacitor (or, in more recent developments, in 10 to 100 ns by the discharge of an infrared laser). If the equilibrium involves an... 

A near-infrared laser pulse at 1.54 pm was used to rapidly heat the aqueous peptide solution 10-20 °C, while a cw ultraviolet probe beam excited the fluorescence of the labeled peptide and monitored the relaxation kinetics. A schematic of the instrument is shown in Figure 1. To produce the temperature jump pulse the fundamental (1064 nm) of a Nd YAG laser (Continuum Surelite I), operating at 1.67 Hz, was focused with a 0.75 m lens into a one meter Raman cell (Princeton Optics, Inc.). The Raman cell contained 600 psi of CH4 and 500 psi of He and had a conversion efficiency of up to 20% for the first Stokes line (1.54 pm). The 1.54 pm wavelength... 

The infrared absorption results presented above demonstrate that it is possible to spectroscopically monitor shock induced chemical reactions on picosecond time scales at the beginning of the reaction zone. This demonstration opens the door to further probing of such events with the myriad of ultrafast laser based spectroscopic tools now available, promising to provide more insight into the effects of extreme pressure and temperature jumps at the molecular scale. 

Thus, we take advantage of the accuracy, robustness and efficiency of the direct problem solution, to tackle the associated inverse heat transfer problem analysis [26, 27] towards the simultaneous estimation of momentum and thermal accommodation coefficients in micro-channel flows with velocity slip and temperature jump. A Bayesian inference approach is adopted in the solution of the identification problem, based on the Monte Carlo Markov Chain method (MCMC) and the Metropolis-Hastings algorithm [28-30]. Only simulated temperature measurements at the external faces of the channel walls, obtained for instance via infrared thermography [30], are used in the inverse analysis in order to demonstrate the capabilities of the proposed approach. A sensitivity analysis allows for the inspection of the identification problem behavior when the external wall Biot number is also included among the parameters to be estimated. 

The global decomposition model of RDX proposed by Brill et al. [12], derived from a well-calibrated temperature-jump/Fourier transform infrared (T-... 

This value has been supported by later work (a) with the microwave temperature-jump technique (G. Ertl and H. Gerischer, Z. Elektrochem. 65 (1961) 629 Z. Elektrochem. 66 (1962) 560) and (b) by infrared iodine-laser initiation (D.M. Goodall, R.C. Greenhow, B. Knighf J.F. Holzwarth and W. Frisch, in W.J. Gettins and E. Wyn-Jones (Eds.), Techniques and Applications of Fast Reactions in Solution, Rei-del, Dordrecht, 1979, p. 567) see, also (c) W.J. Albery, Prog. React. KineL 4 (1%7) 353. 

Brewer, S.H., Song, B.B., Raleigh, D.P., Dyer, R.B. Residue specific resolution of protein folding dynamics using isotope-edited infrared temperature jump spectroscopy. Biochemistry 46, 3279-3285 (2007)... 

From comparison of temperatures measured by different methods, this temperature fluctuation scheme led to conclude that temperature fluctuations are common in nebulae, with typical values of t2 = 0.03 - 0.05 (see references in Peimbert 1996, Stasinska 1998, Mathis et al. 1998, Esteban 2002). The case is not always easy to make the determination of the continuum in the vicinity of the Balmer jump is difficult, the combination of data from different instruments for the comparison of far infrared data with optical ones involves many potential sources of errors, lines of 0++ and of H are not emitted in coextensive zones etc. .. Nevertheless, the observational results seem overwhelming. And, as noted by Peimbert (2002), the value of t2 found in such a way is never negative ... 

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