Flash photolysis, and

Porter G and Topp M R 1968 Nanosecond flash photolysis and the absorption spectra of excited singlet states Nature 220 1228-9... 

The time resolution of these methods is detennined by the time it takes to mitiate the reaction, for example the mixing time in flow tubes or the laser pulse width in flash photolysis, and by the time resolution of the detection. Relatively... 

B2.5.4.2 LASER FLASH PHOTOLYSIS AND PUMP-PROBE TECHNIQUES... 

A recent study of the vibrational-to-vibrational (V-V) energy transfer between highly-excited oxygen molecules and ozone combines laser-flash photolysis and chemical activation with detection by time-resolved LIF [ ]. Partial laser-flash photolysis at 532 mn of pure ozone in the Chappuis band produces translationally-... 

Guldi D M 1997 Capped fullerenes stabilization of water-soluble fullerene monomers as studied by flash photolysis and pulse radiolysis J. Phys. Chem. A 101 3895-900... 

Some of the most important questions one can ask in the study of kinetics concern the rates of reactions of the intermediates. In some cases, values can be obtained by direct experiments. For example, one might generate the intermediate by an independent method capable of producing it much more rapidly than it reacts. Then it can be examined in its own right. Chapter 11 presents methods for doing so, such as flash photolysis and pulse radiolysis. 

Some of the most conclusive studies of the mechanisms of chain reactions come from experiments in which some of the propagating steps have been independently measured directly. This measurement can sometimes be done by the use of flash photolysis and pulse radiolysis (Chapter 11). Such determinations can verify the occurrence of a certain reaction in the sequence and provide its rate constant. 

The optical absorption spectra of sulfonyl radicals have been measured by using modulation spectroscopy s, flash photolysis and pulse radiolysis s techniques. These spectra show broad absorption bands in the 280-600 nm region, with well-defined maxima at ca. 340 nm. All the available data are summarized in Table 3. Multiple Scattering X, calculations s successfully reproduce the experimental UV-visible spectra of MeSO 2 and PhSO 2 radicals, indicating that the most important transition observed in this region is due to transfer of electrons from the lone pair orbitals of the oxygen atoms to... 

Flash Photolysis and Pulse Radiolysis Studies Non-linear Optical Effects 142... 

Two principal methods are employed for the determination of triplet lifetimes flash photolysis and triplet luminescence decay. Since both of these techniques have been discussed previously in some detail, only a short treatment of the application of these techniques to the determination of triplet lifetimes will be given in this section. 

Midinger and Wilkinson<54> have used flash photolysis and fluorescence quenching by heavy atoms to determine the intersystem crossing efficiencies of anthracene and a number of its derivatives. As discussed in Section 5.2b, heavy atoms present as molecular substituents or in the solvent serve to promote multiplicity forbidden transitions. When anthracene is excited the following processes can occur ... 

Laser flash photolysis and time-resolved fluorescence 175... 

LASER FLASH PHOTOLYSIS AND TIME-RESOLVED FLUORESCENCE... 

Much of the achieved advances result from the development and availability of instrumentation to study slow and fast reactions at pressures up to 300 MPa, including stopped-flow, T-jump, P-jump, NMR, ESR, flash-photolysis, and pulse-radiolysis instrumentation (1, 2, 4, 6, 7). Readers are advised to consult the quoted references for more detailed information, since these present a detailed account of the present instrumentation and commercial availability of such equipment. 

The results, displayed in Figure 2.28, show a good agreement between the three methods within their range of applicability, noting that nanosecond laser flash photolysis and redox catalysis have similar capabilities, with a slight advantage to the former method. 

An excess of the twisted form (B) was prepared from the photostable 2,2 -bis(trifluoromethyl)-129c by laser flash photolysis, and its decay to the folded form (A) was followed photometrically. From the rate constants at four temperatures, AH (B- A) = 16.1 0.7 kcal/mol was obtained. For this compound, AH° (A B) = 4.2 kcal/mol had been found, and the sum of these two values agrees well with AG (E- Z) = 21.5 0.3 kcal/mol obtained by band-shape analysis, which probably corresponds to a A// value of 20 to 21 kcal/mol, assuming AS to be -2 to -5 e.u. 

Flash photolysis and pulse radiolysis techniques have been developed to study Fe Ru ET in Ru-modified proteins [21,26,27]. A method that allows study of electron transfer from a surfaee ajRu(IIIXhistidine) to a protein redox center is outlined in the Scheme [21]. The ET reaction is initiated by photogenerated... 

Epr is most effective for detecting free radicals that may occur as intermediates in oxidation and reduction reactions involving transition metal ions. Since these transients are invariably quite labile, epr is combined with continuous flow, (more conveniently) stopped-flow, flash photolysis, and pulse radiolysis. 

An important development for detection of transient organometallic species is fast time-resolved infrared. The transient is generated rapidly by uv-visible flash photolysis and monitored by ir with ps resolution. Spectra are obtained from a series of kinetic traces recorded at about 4 cm interval. 

Saini, R.D., Dhanya, S., and Das, T.N. Lasder (248 nm) flash photolysis and pnlse radiolysis of Cp2Br2 in aqueous solution atmospheric implications. Bull Chem. Soc. Jpn., 75(8) 1699-1705, 2002. 

Absolute rate constants for the reaction of Et3SiH with aroyloxyl radicals 26 (Reaction 3.17) were measured by laser flash photolysis and were found to be in the range of (3.8-7.4) x 10 s at 24 °C [32]. The rate constants of t-BuO ... 

A rapid reaction kinetic technique (time scale = 10-1000 ps) that typically uses a Van de Graff accelerator or a microwave linear electron accelerator to promptly generate a pulse of electrons at sufficient power levels for excitation and ionization of target substances by electron impact. The technique is the direct radiation chemical analog of flash photolysis and the ensuing kinetic measurements are accomplished optically by IR/visible/UV adsorption spectroscopy or by fluorescence spectroscopy. 

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