Pulsed techniques, electron paramagnetic resonance

Electron-nuclear double resonance (ENDOR) spectroscopy A magnetic resonance spectroscopic technique for the determination of hyperfine interactions between electrons and nuclear spins. There are two principal techniques. In continuous-wave ENDOR the intensity of an electron paramagnetic resonance signal, partially saturated with microwave power, is measured as radio frequency is applied. In pulsed ENDOR the radio frequency is applied as pulses and the EPR signal is detected as a spin-echo. In each case an enhancement of the EPR signal is observed when the radiofrequency is in resonance with the coupled nuclei. 

Experimental Techniques A absorption CIMS = chemical ionization mass spectroscopy CK = competitive kinetics DF discharge flow EPR = electron paramagnetic resonance FP = flash photolysis FT = flow tube FTIR Fourier transform intra-red GC = gas chromatography, UF = laser induced fluorescence LMR = laser magnetic resonance MS = mass spectroscopy PLP = pulsed laser photolysis SC = smog chamber SP = steady (continuous) photolysis UVF = ultraviolet flourescence spectroscopy... 

In this section we report the first study of the micro-SQUID response of a low-spin molecular system, V15, to electromagnetic radiation. The advantages of our micro-SQUID technique in respect to pulsed electron paramagnetic resonance (EPR) techniques consist in the possibility to perform time-resolved experiments (below 1 ns) [59] on submicrometer sizes samples (about 1000 spins) [22] at low temperature (below 100 mK). Our first results on Vi5 open the way for time-resolved observations of quantum superposition of spin-up and spin-down states in SMMs. Other results obtained in similar systems but with large spins concern for example EPR measurements [10], resonant photon-assisted tunneling in a Feg SMM [60]. 

A pulsed technique in electron paramagnetic resonance, in some ways analogous to pulsed techniques in NMR (nuclear magnetic resonance... 

Direct assays for SOD have relied on pulse radiolysis (K12.M15), stopped-flow spectroscopy (M4,M17), rapid-flow electron paramagnetic resonance (EPR) (Bl,05, SI), polarographic techniques (R4), and nuclear magnetic resonance (NMR) spectroscopy (R3). 

Recently, the SP-PLP-electron paramagnetic resonance (EPR) technique has been introduced as a direct method for kt measurement, in which EPR detection is used to trace the decay of radicals after laser pulse initiation.This novel technique has however not yet been applied at high pressures. 

Now, pulse Fourier spectroscopy is the preferred experimental technique in NQR. It was made possible by the introduction of inexpensive computers and by the development of FFT algorithms. Note that the principles of Fourier spectroscopy are well developed and widely used in other fields of spectroscopy, including magnetic resonance, electron paramagnetic resonance etc. Several monographs are available on this subject. The reader is referred to the... 

A powerful technique to detect paramagnetic radical species, such as the one-electron reduced 7t-radical anions (Ceo ) and oxidized 7t-radical cation (Ceo ) is electron spin resonance (ESR) (9,10). Studies, regarding the characterization of fullerene intermediates via employing the ESR technique are, however, still somewhat controversial. Absorption spectrophotometry, on the other hand, is been successfully employed in matrix irradiation, silver mirror reduction in tetrahydrofuran (THF), and detection of transients in time-resolved laser photolysis and pulse radiolysis (10,11). 

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