Hartmann-Hahn transfer

These intermolecular correlation peaks mean that intermolecular cross polarization (CP) occurs between the carbon and proton of intermolecular -interacting polypeptides in blend. There may be two pathways for the observed intermolecular CP. One is that a direct transfer from proton to carbon exists, and another is that a change in the magnetization by spin diffusion (homonuclear Hartmann Hahn transfer) exists. It is thought that the former is much more efficient than the latter because the former comes from only one magnetization transfer process, but the latter comes from two... 

Homonuclear and Heteronuclear Hartmann-Hahn Transfer in Isotropic Liquids... 

D. Multiple-Step Selective Hartmann-Hahn Transfer... 

As demonstrated by Hartmann and Hahn (1962), energy-matched conditions can be created with the help of rf irradiation that generates matched effective fields (see Section IV). Although Hartmann and Hahn focused on applications in the solid state in their seminal paper, they also reported the first heteronuclear polarization-transfer experiments in the liquid state that were based on matched rf fields. A detailed analysis of heteronuclear Hartmann-Hahn transfer between scalar coupled spins was given by Muller and Ernst (1979) and by Chingas et al. (1981). Homonuclear Hartmann-Hahn transfer in liquids was first demonstrated by Braunschweiler and Ernst (1983). However, Hartmann-Hahn-type polarization-transfer experiments only found widespread application when robust multiple-pulse sequences for homonuclear and heteronuclear Hartmann-Hahn experiments became available (Bax and Davis, 1985b Shaka et al., 1988 Glaser and Drobny, 1990 Brown and Sanctuary, 1991 Ernst et al., 1991 Kadkhodaei et al., 1991) also see Sections X and XI). 

Various authors have used different names for Hartmann-Hahn-type experiments that emphasize distinct experimental or theoretical aspects. For example, heteronuclear Hartmann-Hahn transfer in liquids has been called coherence transfer in the rotating frame (Muller and Ernst, 1979), J cross-polarization (JCP Chingas et al., 1981), heteronuclear crosspolarization (Ernst et al., 1991), HEHAHA (heteronuclear Hartmann-Hahn transfer Morris and Gibbs, 1991), and hetero TOCSY (total correlation spectroscopy Brown and Sanctuary, 1991). Homonuclear Hartmann-Hahn transfer has been referred to as TOCSY (Braunschweiler... 

In this article, the basic principles of Hartmann-Hahn transfer in isotropic liquids will be revealed and the most important tricks of the trade will be disclosed. We hope that this will dispel the mystique surrounding Hartmann-Hahn experiments without reducing the fascination with this potent and multifaceted experimental technique. 

HARTMANN HAHN TRANSFER IN ISOTROPIC LIQUIDS of the zero-quantum operators... 

More generally, C = 0 if the effective coupling term 2irI,J J Iy is a zero-quantum operator in the effective field frame that is defined by and Bf (see Section II) and if the effective fields are matched (ly B l = lyyBj 1). Because these conditions are identical with the conditions for efficient Hartmann-Hahn transfer, the approximation... 

A Theorem Relating Hartmann-Hahn Transfer and Cross-Relaxation... 

Schleucher et al., 1995b, 1996). This relation has important consequences for the suppression of Hartmann-Hahn transfer in ROESY experiments. The relationship shows that the suppression of Hartmann-Hahn transfer ( A = max ) and the suppression of longitudinal cross relaxation (Ih / I = min ) are in fact conflicting goals. The best a sequence can do is... 

Even in the absence of relaxation, Hartmann-Hahn transfer depends on a large number of parameters pulse sequence parameters (multiple-pulse sequence, irradiation frequency, average rf power, etc.) and spin system parameters (size of the spin system, chemical shifts, /-coupling constants). For most multiple-pulse sequences, these parameters may be destilled into effective coupling tensors, which completely determine the transfer of polarization and coherence in the spin system. This provides a general classification scheme for homo- and heteronuclear Hartmann-Hahn experiments and allows one to characterize the transfer properties of related... 

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