Creation of nearly-equivalent nuclear spin singlet states using spin-lock induced crossing

Abstract

Methods and systems for Nuclear Magnetic Resonance (NMR) spectra of samples having unresolved peaks are described. The methods and systems allow for the creation nuclear spin singlet states in nearly-equivalent spin pairs, for example, using continuous spin-locking with a nutation frequency matched to the coupling strength between spins.

What is claimed is: 
     
         1 . A method for acquiring a J-coupling information containing spectrum of a target molecule comprising measuring magnetization transfer between spin states as a function of the spin-lock nutation frequency. 
     
     
         2 . The method of  claim 1 , further comprising measuring magnetization as a function of spin lock duration time. 
     
     
         3 . The method of  claim 1 , further comprising generating the J-coupling information containing spectrum. 
     
     
         4 . The method of  claim 1 , further comprising chemically identifying the target molecule based on the generated J-coupling information containing spectrum. 
     
     
         5 . The method of  claim 1 , wherein the target molecule contains at least a pair of strongly-coupled spins. 
     
     
         6 . The method of  claim 5 , wherein the pair of strongly coupled spins are both  1 H. 
     
     
         7 . The method of  claim 5 , wherein the pair of strongly coupled spins are both  13 C,  15 N,  17 O,  19 F or  31 P. 
     
     
         8 . The method of  claim 1 , wherein the method is performed at a magnetic field strength of less than 2 T or less than 100 mT. 
     
     
         9 . The method of  claim 8 , wherein the method is performed at a magnetic field strength of less than 10 mT. 
     
     
         10 . A method comprising selectively creating a nuclear spin singlet state in a target molecule having a nearly-equivalent pair of nuclei by applying continuous spin-locking with parameters that are optimized to transfer magnetization from the triplet state to the singlet state. 
     
     
         11 . The method of  claim 10 , further comprising transferring magnetization from the singlet state back to the triplet state. 
     
     
         12 . The method of  claim 10 , further comprising measuring magnetization as a function of spin lock nutation frequency. 
     
     
         13 . The method of  claim 10 , further comprising measuring magnetization as a function of spin lock duration time. 
     
     
         14 . The method of  claim 10 , wherein the resonance frequency difference between the nuclei is less than 1/(spin lattice relaxation time). 
     
     
         15 . The method of  claim 10 , wherein the pair of nearly-equivalent nuclei are both  1 H. 
     
     
         16 . The method of  claim 10 , wherein the pair of nearly equivalent nuclei are both  13 C,  15 N,  17 O,  19 F or  31 P. 
     
     
         17 . The method of  claim 10 , wherein the method is performed at a magnetic field strength of more than 2 T. 
     
     
         18 . The method of  claim 17 , wherein the method is performed at a magnetic field strength of more than 2 T but less than 26 T. 
     
     
         19 . The method of  claim 17 , wherein the method is performed at a magnetic field strength of more than 4.5 T. 
     
     
         20 . An nuclear magnetic resonance (NMR) system comprising:
 (a) an NMR transceiver including a radiofrequency (RF) generator configured to generate a sequence of RF fields having controllable parameters, and to apply the RF field sequence to a sample; and   (b) a controller configured to generate and optionally relay a set of instructions to the transceiver to perform the method of  claim 1 .   
     
     
         21 . An nuclear magnetic resonance (NMR) system comprising:
 (a) an NMR transceiver including a radiofrequency (RF) generator configured to generate a sequence of RF fields having controllable parameters, and to apply the RF field sequence to a sample; and   (b) a controller configured to generate and optionally relay a set of instructions to the transceiver to perform the method of  claim 10 .   
     
     
         22 . A system comprising a computer readable medium including instructions that when executed cause an NMR transceiver including an RF generator to generate a sequence of RF fields to perform the method of  claim 1 . 
     
     
         23 . A system comprising a computer readable medium including instructions that when executed cause an NMR transceiver including an RF generator to generate a sequence of RF fields to perform the method of  claim 10 .