Double-resonance

Early P NMR studies were often performed on non-rotating samples 

Resonance) methodology [3], In this approach one takes advantage of 

In addition to allowing the determination of the P chemical shift this double resonance method provides a means by which the relative signs of coupling involving P can be determined. The primary advantage of the INDOR technique lies in its use of relatively sensitive nuclei to obtain data on less receptive systems. 

The principle shortcoming of this method is that it requires that the molecule contains a readily observable resonance to which the phosphorus atom is coupled. Unfortunately, this is not always convenient. 

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Callegari A, Rebstein J, Muenter J S, Jost R and Rizzo T R 1999 The spectroscopy and intramolecular vibrational energy redistribution dynamics of HOCI in the u(OH) = 6 region, probed by infrared-visible double resonance overtone excitation J. Chem. Phys. 111 123-33... 

Figure Bl.12.15. Some double-resonance pulse sequences for providing distance infomiation in solids (a) SEDOR, (b) REDOR, (c) TEDOR and (d) TRAPDOR. In all sequences the narrow pulses are 90° and the wide pulses 180°. For sequences that employ MAS the luimber of rotor cycles N is shown along the bottom.

B1.15.5.1 ELECTRON-NUCLEAR DOUBLE RESONANCE SPECTROSCOPY (ENDOR)... 

For the simple system discussed above the advantages of perfonning double resonance do not become so... 

ELDOR is tlie acronym for electron-electron double resonance. In an ELDOR experiment [28] one observes a rednction in the EPR signal intensity of one hyperfme transition that results from the saturation of another EPR transition within the spin system. ELDOR measurements are still relatively rare bnt the experiment is fimily established in the EPR repertoire. 

Leniart D S 1979 Instrumentation and experimental methods in double resonance Multiple Electron Resonance Spectroscopy ed M M Doric and J H Freed (New York Plenum) ch 2, pp 5-72... 

Freed J H 1969 Theory of saturation and double resonance effects in ESR spectra. IV. Electron-nuclear triple resonance J. Chem. Rhys. 50 2271-2... 

Hyde J S, Chien J C W and Freed J 1968 Electron-electron double resonance of free radicals In solution J. Chem. Phys. 48 4211-26... 

Gemperle C and Schwelger A 1991 Pulsed electron-nuclear double resonance methodology Chem. Rev. 91 1481-505... 

IR-UV double resonance also selective for S and C Reaction of both Isotopes with high selectivity (high fluence)... 

Fehrensen B, Hippier M and Quack M 1998 Isotopomer selective overtone spectroscopy by ionization detected IR + UV double resonance jet-cooled aniline Chem. Phys. Lett. 298 320-8... 

Double resonance modulated spectroscopy pyridines and benzo derivatives, 2, 104 Dowicil S-13 as fungicide, 2, 515 Doxepin... 

Dipole—dipole (heteronuclear) Af (hetero) Spin-echo double resonance (SEDOR) ... 

A number of other, more sophisdcated, selective averaging tools (includli spin echo, double resonance and two-dimensional techniques) are available, both for spectral editing purposes and for obtaining quantitadve information about inter-... 

Electron nuclear double resonance of transition metal complexes with organic ligands. A. Schweiger, Struct. Bonding (Berlin), 1982, 51, 1-119 (294). 

Schweiger A (1982) Electron Nuclear Double Resonance of Transition Metal Complexes with Organic Ligands. 51 1-122 Scozzafava A, see Bertini I (1982) 48 45-91... 

One-dimensional double-resonance or homonuclear spin-spin decoupling experiments can be used to furnish information about the spin network. However, we have to irradiate each proton signal sequentially and to record a larger number of ID H-NMR spectra if we wish to determine all the coupling interactions. Selective irradiation (saturation) of an individual proton signal is often difficult if there are protons with close chemical shifts. Such information, however, is readily obtainable through a single COSY experiment. 

Vibrationally mediated photodissociation (VMP) can be used to measure the vibrational spectra of small ions, such as V (OCO). Vibrationally mediated photodissociation is a double resonance technique in which a molecule first absorbs an IR photon. Vibrationally excited molecules are then selectively photodissociated following absorption of a second photon in the UV or visible [114—120]. With neutral molecules, VMP experiments are usually used to measure the spectroscopy of regions of the excited-state potential energy surface that are not Franck-Condon accessible from the ground state and to see how different vibrations affect the photodissociation dynamics. In order for VMP to work, there must be some wavelength at which vibrationally excited molecules have an electronic transition and photodissociate, while vibrationally unexcited molecules do not. In practice, this means that the ion has to have a... 

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