Time-resolved FTIR spectroscopy

The carboxylation of ethylenediamine (229) is first order in protonated (229) and the rate constant was an order of magnitude lower than that for (229) under identical conditions.204 The effects of solvents on the decomposition kinetics of some diacyl peroxidases (230) was assessed using time-resolved FTIR spectroscopy at <3 kbar and <155 °C.205... 

P 26] Time-resolved FTIR spectroscopy was performed by operation of an infrared spectrometer in the rapid scan acquisition mode (see Figure 1.59) [110]. The effective time span between subsequent spectra was 65 ms. Further gains in time resolution can be achieved when setting the spectral resolution lower (here 8 cm4) or by using the step-scan instead of rapid-scan mode. 

Chen, X., Shao, Z.Z., Knight, D.P., and Vollrath, F. "Conformation transition of silk protein membranes monitored by time-resolved FTIR spectroscopy Effect of alkali metal ions on Nephila spidroin membrane". Acta Chimica Sinica 60(12), 2203-2208 (2002c). 

The discussion of the recent results concerning the ethene polymerization on the Phillips catalyst demonstrates that temperature- and time-resolved FTIR spectroscopy (where both temperature and time change simultaneously during the experiment), together with an accurate control of the pressure conditions, has been decisive in clarifying the nature of the adsorbed species and of some of the precursor species present in the first stages of the polymerization reaction. Further advances in this direction may be achieved by increasing the sensitivity of the technique. 

In this review we have shown that time-resolved FTIR spectroscopy (with temperature and pressure held constant during the experiment) and temperature-time resolved FTIR spectroscopy (with both temperature and time changing simultaneously in a controlled way during the experiment) allow the detection of surface transient species in surface-catalyzed reactions. Several examples are reported, which can be classified in the following main categories ... 

Gerwert K. Molecular reaction mechanisms of proteins monitored by time-resolved FTIR-spectroscopy. Biol. Chem. 1999 380 931-935. 

Thus, this paper gives tantalising glimpses of the possible applications of in-situ rapid-scan time-resolved FTIR spectroscopy. Unlike the digital time-resolved technique, the rapid-scan method does not require reaction reversibility and may thus have wider application. The technique does have its limitations, however. 

The transient kinetics of NiR turnover has been studied using stopped-flow absorbance, rapid-quench EPR, and time-resolved FTIR spectroscopy. Stopped-flow/quenched EPR showed that nitrite binds to the ferrous heme d of PaNiR and was reduced to NO within the dead time of the apparatus to form an EPR-silent ferric NO heme d complex." The subsequent transient with a rate constant of 1 s was assigned to electron transfer from heme c to heme d. The final species corre onded to the EPR-detectable NO-heme d complex of fully reduced enzyme. A later study detected the mixed valence heme c -heme i/i NO species at 6 ms after mixing before formation of the fully reduced NO complex. 

Skupin H, Kremer F, Shilov SV, Stein P, Finkelmann H (1999) Time-resolved FTIR spectroscopy on structure and mobility of single crystal ferroelectric liquid crystalline elastomers. Macromolecules 32 3746... 

Time-resolved FTIR spectroscopy measurements were performed under isothermal crystallisation conditions to clarify the origin of the cocrystallisation and phase segregation phenomena observed for a series of PE blends between the deuterated and hydrogenated species, The degree of undercooling or the temperature jump depth (i.e., the size of the temperature drop) from the molten state to the isothermal crystallisation temperature was controlled (96). 

Successful concepts for "reaction-modulated" IR difference spectroscopy use the multiplex advantage of FTIR spectroscopy or the availability of high-intensity laser IR sources. A kinetic photometer using tunable IR diode lasers as sources for the mid-infrared has been developed in our laboratory and will be described elsewhere [6]. It covers the time-domain from approx. 500 nsec to some seconds. A second approach is time-resolved FTIR spectroscopy using a rapid-scanning interferometer, several scans can be recorded per second and the time-domain of slow reactions thus be covered [7]. The following schemes illustrate both concepts ... 

The reorientation of liquid crystals in an external electric field is the basis of their technical application in liquid-crystal displays (LCDs) and has been treated in numerous books and reviews [1-3, 12, 38, 46 50]. This section is intended to demonstrate the application of time-resolved FTIR spectroscopy for a better understanding of the electro-optical performance of liquid-crystalline systems. Due to the reversible character of the orientational and relaxational motions of liquid crystals under the perturbation of an electric field, the time-resolution of the FTIR measurements can be extended down to the microsecond range by the implementation of the step-scan technique (see Section 2.2). Thus, an insight on a molecular level... 

Kotting, C., Gerwert, K. Proteins in action monitored by time-resolved FTIR spectroscopy. Chemphyschem. 6, 881—888 (2005)... 

Steady-State and Time-Resolved FTIR Spectroscopy of Quinones in Bacterial Reaction Centers... 

Musto, P, Mensitieri, G., Cotugno, S., Guerra, G, Veuditto, V. Probing by time-resolved FTIR spectroscopy mass transport, molecular iuteractions, and conformational ordering in the system chloroform-syndiotactic polystyrene. Macromolecules, 35(6), 2296-2304 (2002). 

Another field of time-resolved FTIR spectroscopy relates to polymeric liquid crystals, with the rate of electric field reorientation of nematic liquid crystals (100] and the orientation of strands in liquid crystals [101] each having been monitored using this technique. 

Nito, K., H. Takanashi, and A. Yasuda. 1995. Dynamics of FLCs with a tilted bookshelf structure using time-resolved FTIR spectroscopy. Liq. Cryst. 19 (5) 653-658. 

The crystallisation behaviour of polyphenylene sulphide was studied using time-resolved FTIR spectroscopy and the results obtained correlated with DSC measurements. The 1073 cm/1 amorphous band was selected for the time-resolved measurements. The procedure provided details on the microstructure of the PPS, including heterogeneity of the amorphous phase above and below Tg. A method is proposed for calculating the rigid, amorphous fraction in terms of the increase in the slope of the absorbance variation with temperature at the glass transition. 43 refs. CHINA JAPAN... 

Rapid kinetics or in-situ observation of the curing reaction mechanism using time-resolved FTIR spectroscopy [13] can provide valuable information about the volume collapse or hardening route in the complex ceramer network. The residual porosity V in the coating structure can be determined by FTIR analysis using the following equation [14] ... 

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