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O Schedletzky

Publications and source records attributed to O Schedletzky.

7 recordsLinked to original sources
PubMed1999

Analytical polarization transfer functions for four coupled spins 12 under isotropic mixing conditions

Analytical polarization transfer functions are presented for spin systems consisting of four spins 12 with arbitrary coupling constants under isotropic mixing conditions. In addition, simplified transfer functions were derived for symmetric coupling topologies. Based on these transfer functions optimal durations for the mixing period can be determined for correlations of interest. Copyright 1999 Academic Press.

Journal Article↗
PubMed1998

Unitary control in quantum ensembles: maximizing signal intensity in coherent spectroscopy

Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.

Journal Article↗
PubMed1998

Analytical Polarization and Coherence Transfer Functions for Three Coupled Spins 1/2 under Planar Mixing Conditions

Analytical polarization and coherence transfer functions are presented for spin systems consisting of three spins 1/2 with arbitrary coupling constants under planar mixing conditions. In addition, simplified transfer functions were derived for symmetric coupling topologies. Based on these transfer functions optimal durations for the mixing period can be determined for correlations of interest. Copyright 1998 Academic Press. Copyright 1998 Academic Press

Journal Article↗
PubMed1998

Investigating catalytic processes with parahydrogen: evolution of zero-quantum coherence in AA'X spin systems

A systematic outline for the elucidation of the nature of hydrogenation intermediates with a lifetime too short to be directly detectable with standard NMR methods is presented. The method takes advantage of the special nature of the parahydrogen density operator and its inherent enhancement factor. The key aspect of these experiments is the evolution of zero-quantum coherence which is contained in the parahydrogen density operator. Analytical coherence transfer functions have been derived which describe the evolution of this zero-quantum coherence in spin systems consisting of three spins 1/2 that form an AA'X spin system. The analytical expressions presented form a basis for a thorough investigation of crucial catalytic steps. Copyright 1998 Academic Press.

Journal Article↗
PubMed1994

A general enhancement scheme in heteronuclear multidimensional NMR employing pulsed field gradients.

General pulse sequence elements that achieve sensitivity-enhanced coherence transfer from a heteronucleus to protons of arbitrary multiplicity are introduced. The building blocks are derived from the sensitivity-enhancement scheme introduced by Cavanagh et al. ((1991) J. Magn. Reson., 91, 429-436), which was used in conjunction with gradient coherence selection by Kay et al. ((1992) J. Am. Chem. Soc., 114, 10663-10665), as well as from a multiple-pulse sequence effecting a heteronuclear planar coupling Hamiltonian. The building blocks are incorporated into heteronuclear correlation experiments, in conjunction with coherence selection by the formation of a heteronuclear gradient echo. This allows for efficient water suppression without the need for water presaturation. The methods are demonstrated in HSQC-type experiments on a sample of a decapeptide in H2O. The novel pulse sequence elements can be incorporated into multidimensional experiments.

Amino Acid Sequence↗