Indirect laser-induced temperature

The time range of the electrochemical measurements has been decreased considerably by using more powerful -> potentiostats, circuitry, -> microelectrodes, etc. by pulse techniques, fast -> cyclic voltammetry, -> scanning electrochemical microscopy the 10-6-10-1° s range has become available [iv,v]. The electrochemical techniques have been combined with spectroscopic ones (see -> spectroelectrochemistry) which have successfully been applied for relaxation studies [vi]. For the study of the rate of heterogeneous -> electron transfer processes the ILIT (Indirect Laser Induced Temperature) method has been developed [vi]. It applies a small temperature perturbation, e.g., of 5 K, and the change of the open-circuit potential is followed during the relaxation period. By this method a response function of the order of 1-10 ns has been achieved. 

Transient technique — A technique whose response is time dependent and whose time dependence is of primary interest, e.g., -> chronoamperometry, -> cyclic voltammetry (where current is the transient), -> chronopotentiometry and -> coulostatic techniques (where voltage is the transient). A transient technique contrasts with steady-state techniques where the response is time independent [i]. Some good examples are cyclic voltammetry [i, ii] (fast scan cyclic voltammetry), the indirect-laser-induced-temperature-jump (ILIT) method [iii], coulostatics [i]. The faster the transient technique, the more susceptible it is to distortion by -> adsorption of the redox moiety. 

Refs. [i] Bard AJ, FaulknerLR (2001) Electrochemical methods, 2nd edn. Wiley, New York, pp 487-516 [ii] Amatore C, Maisonhaute E (2005) Anal Chem 77-.303A [iii] FeldbergSW, Newton MD, Smalley JF (2003) The indirect laser-induced temperature jump method for characterizing fast interfacial electron transfer concept, application, and results. In Bard AJ, Rubinstein I (eds) Electroanalytical chemistry, vol. 22. Marcel Dekker, New York, pp 101-180... 

An adaptation of the temperature-jump method, named indirect laser-induced temperature jump [29], was used in studies of distance dependence of electron transfer at electrodes. A pulsed Nd YAG laser was used to cause a sudden (<5 ns) change in temperature (<5 K) at an electrode/electrolyte interface. The increase in temperature causes a change in the open-circuit potential. The relaxation step is a function of the dissipation of thermal energy and the rate of electron transfer between the electrode and its redox partners. 

ILIT Indirect laser-induced temperature jump (technique)... 

For SAMs with attached redox molecules, k (units of s ) can be measured by cychc voltammetry, chronoamperome-try (CA), alternating current impedance spectroscopy (ACIS), alternating current voltammetry (AGV), AG electroreflectance spectroscopy, and an indirect laser-induced temperature (ILIT) jump method. 

THE INDIRECT LASER-INDUCED TEMPERATURE-JUMP METHOD FOR CHARACTERIZING FAST INTERFACIAL ELECTRON TRANSFER CONCEPT, APPLICATION, AND RESULTS... 

The objective of this chapter is to describe the indirect laser induced temperature method (ILIT) - an approach for studying heterogeneous electron transfer ILIT is particularly useful for studying systems where the redox species are attached to the electrode. Our focus will be on the fundamentals of the ILIT methodology and some of the questions that might be answered with its application. 

A fundamental reason for measuring rates of electron transfer (ET) is to identify the physical-chemical factors that control those rates and to learn how to control those factors. For the past several years we have focused our experimental efforts on the measurement of the heterogeneous electron-transfer rate constant, k° (units s ), for systems where the redox species are covalently attached to the electrode by any of a variety of molecular tethers [1-3]. The indirect laser-induced temperature method, which we developed [4-6], has the capability of measuring k° values as large as 10 s and has proven to be ideally suited for these types of studies. We will show some recent development that we anticipate will allow the measurement of k° values greater than 10 s . ... 

Ratios Lred /kmd and Lq J/k [see Eq. (27)] Coupling constant for electron transfer Indirect laser-induced temperature-jump method Indices indicating ILIT medium 1 (quartz),... 

Smalley, I, L. Geng, A. Chen, S. Feldberg, N. Lewis, and G. Cali (2003). An indirect laser-induced temperature jump study of the influence of redox couple adsorption on heterogeneous electron transfer kinetics. Journal of Electroanalytical Chemistry 549, 13-24. 

The Indirect Laser-Induced Temperature Jump Method for Characterizing Fast Interfacial Electron Transfer Concept, Application, and Resnlts,... 

Refs. [i] Eigen M (1954) Discuss Faraday Soc 17 194 [ii] Norrish RGW, Porter G (1949) Nature 164 658 (1952) Proc RSocA 210 439 [Hi] Dian EW-G, Herek JL, Kim ZH, Zewail AH (1999) Science 279 847 [iv] Bard A] (1992) Pure Appl Chem 64 185 [v] Bard A], Fan F-R, Mirkin MV (1994) Scanning electrochemical microscopy. In Bard A] (ed) Electroanalytical chemistry, vol. 18. Marcel Dekker, New York [vi] Neudeck A, Marken F, Compton RG (2002) UV/Vis/NIR spectroelectrochemistry. In Scholz F (ed) Electroanalytical methods. Springer, Berlin, pp 167-189 [vii] FeldbergSW, Newton MD, Smalley JF (2004) The indirect laser-induced temperature jump methodefor characterizing fast interfacial electron tranter concept, application, and results. In Bard A], Rubinstein I (eds) Electroanalytical chemistry, vol. 22. Marcel Dekker, New York, pp 101-180... 

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